Medical conditions library
Explainers for the most-searched conditions where lab tests carry weight. Each entry links to the primary markers, the symptoms to watch for, and the next clinical step.
Iron-deficiency anaemia
The most common form of anaemia, caused by depleted iron stores. Fully treatable with iron repletion once the source of loss is found.
ReadICD-10 R73.03Prediabetes
Blood sugar elevated above normal but not yet at the diabetes threshold. Reversible in most patients with structured lifestyle change.
ReadICD-10 E03.9Hypothyroidism
Underactive thyroid — the gland produces too little hormone. The leading global cause in iodine-replete populations is autoimmune (Hashimoto's).
ReadICD-10 E11Type 2 Diabetes
Insulin resistance plus relative beta-cell decline. The leading metabolic disease worldwide, often reversible or remitting in early stages with weight loss.
ReadICD-10 E88.81Metabolic Syndrome
A cluster of cardio-metabolic abnormalities — central obesity, insulin resistance, dyslipidaemia, hypertension — that together raise diabetes and cardiovascular risk far beyond any single component.
ReadICD-10 E05.9Hyperthyroidism
Overactive thyroid producing excess hormone. Suppresses TSH near zero; Graves' disease is the leading global cause.
ReadICD-10 K76.0Non-Alcoholic Fatty Liver Disease (NAFLD)
Excess fat accumulation in the liver unrelated to alcohol. The most common chronic liver disease worldwide and the leading cause of mildly elevated liver enzymes.
ReadICD-10 I10Hypertension
Chronically elevated blood pressure. The largest single contributor to cardiovascular and stroke risk globally; usually asymptomatic until end-organ damage appears.
ReadICD-10 D63.8Anaemia of Chronic Disease
A normocytic anaemia caused by chronic inflammation, infection or malignancy. The second-most-common anaemia worldwide after iron deficiency.
ReadICD-10 M10Gout
Crystal-arthritis caused by monosodium urate deposition. Classically a sudden, exquisitely painful big-toe attack — but the long-term picture is a chronic disease driven by elevated uric acid.
ReadICD-10 K76.0Fatty Liver Disease
Excess fat accumulation in liver cells, regardless of cause. Covers the spectrum from simple steatosis to non-alcoholic steatohepatitis (NASH) and alcoholic liver disease — the most common chronic liver pathology worldwide.
ReadICD-10 E88.81Insulin Resistance
The upstream metabolic defect behind prediabetes, type 2 diabetes, fatty liver and metabolic syndrome. Reversible in most patients caught early — but rarely measured because fasting insulin is uncommon on routine panels.
ReadICD-10 M81Osteoporosis
Loss of bone density and strength that raises fracture risk. Silent until a fracture occurs — the lab work-up identifies treatable contributors.
ReadICD-10 K21.9Gastroesophageal Reflux Disease (GERD)
Chronic acid reflux causing heartburn, regurgitation and oesophageal injury. One of the most common chronic GI conditions — lifestyle and acid suppression are first-line treatment.
ReadICD-10 E28.2Polycystic Ovary Syndrome (PCOS)
Endocrine disorder affecting roughly 10% of women of reproductive age. Combines irregular periods, androgen excess and ovarian morphology — the metabolic dimension drives lab work-up.
ReadICD-10 M06.9Rheumatoid Arthritis
Chronic autoimmune disease causing symmetric inflammation of multiple joints. Early diagnosis and disease-modifying therapy prevent the joint destruction that defined RA a generation ago.
ReadICD-10 J45Asthma
Chronic airway inflammation causing reversible bronchoconstriction. Diagnosed clinically and by spirometry; lab work plays a supporting role.
ReadICD-10 E55.9Vitamin D deficiency
One of the most common nutritional deficiencies worldwide, easily corrected with supplementation once recognised.
ReadICD-10 N18Chronic kidney disease (CKD)
Gradual loss of kidney function over months to years, staged by eGFR. Early stages are usually silent and only revealed by routine blood and urine testing.
ReadICD-10 E53.8Vitamin B12 deficiency
Common, often-missed deficiency that can cause macrocytic anaemia, fatigue and — if untreated — irreversible nerve damage. Easily diagnosed and treated once spotted.
ReadICD-10 K90.0Coeliac disease
Autoimmune intestinal disease triggered by gluten. Highly under-diagnosed; presents with iron deficiency, vitamin malabsorption, GI symptoms — or often nothing obvious.
ReadICD-10 E06.3Hashimoto's thyroiditis
The autoimmune destruction of the thyroid gland, and the leading cause of hypothyroidism in iodine-sufficient countries. Slowly progressive; managed lifelong with thyroxine replacement.
ReadICD-10 E78.01Familial hypercholesterolemia
Genetic disorder of LDL clearance — patients are born with high LDL and face a dramatically elevated risk of early heart attack. Very treatable if recognised in time.
ReadICD-10 E83.110Hereditary hemochromatosis
Genetic iron-overload disease. Iron gradually accumulates over decades and damages liver, heart and pancreas. Highly treatable if caught before organ damage — bloodletting (phlebotomy) is the mainstay.
ReadICD-10 E80.4Gilbert syndrome
Benign genetic variant causing mildly raised unconjugated bilirubin and occasional yellowing of the eyes. Harmless — no treatment needed — but worth knowing because it explains otherwise puzzling lab results.
ReadICD-10 K74.60Liver cirrhosis
End-stage scarring of the liver from any chronic insult. Once compensated cirrhosis becomes decompensated (ascites, varices, encephalopathy, jaundice) the prognosis worsens sharply — but lifestyle change + treatment can stop or reverse early disease.
ReadICD-10 O24.4Gestational diabetes
Diabetes diagnosed for the first time during pregnancy. Usually resolves after delivery but raises lifetime risk of type 2 diabetes by ~50%. Tight control during pregnancy protects mother and baby.
ReadICD-10 K86.1Chronic pancreatitis
Long-standing pancreatic inflammation leading to scarring, exocrine insufficiency (poor fat digestion), endocrine failure (diabetes) and persistent abdominal pain. Common after years of heavy alcohol use; also genetic, autoimmune, gallstone-related, or idiopathic.
ReadICD-10 D69.3Immune thrombocytopenia (ITP)
Autoimmune destruction of platelets causes isolated low platelet count, with bruising, petechiae and bleeding risk. Usually triggered by infection in children (often resolves) or chronic in adults.
ReadICD-10 M35.0Sjögren's syndrome
Autoimmune disease that destroys moisture-producing glands — classically causing dry eyes and dry mouth — but with systemic features (joint pain, fatigue, lymphoma risk) that elevate it above a cosmetic nuisance.
ReadICD-10 E20.9Hypoparathyroidism
Low parathyroid hormone causes persistent low blood calcium with high phosphate — leading to tingling, muscle cramps, seizures and cataracts if untreated. Most often from neck surgery; less commonly autoimmune or genetic.
ReadICD-10 E27.1Addison's disease
Failure of the adrenal cortex to produce cortisol and aldosterone. Slow-burning fatigue, hyperpigmentation, salt craving and low blood pressure — but acutely it can present as a life-threatening adrenal crisis with shock and hyperkalaemia.
ReadICD-10 N80Endometriosis
Estrogen-dependent inflammatory disorder where endometrial-like tissue grows outside the uterus. Causes painful periods, pelvic pain, deep dyspareunia, and infertility in 30–50% of affected women.
ReadICD-10 N40Benign prostatic hyperplasia (BPH)
Non-cancerous enlargement of the prostate. Common after age 50 — half of men in their 60s and 80% by 80. Causes lower-urinary-tract symptoms (frequency, weak stream, nocturia); rarely life-threatening but quality-of-life-impairing.
ReadICD-10 N20.0Nephrolithiasis (kidney stones)
Crystalline stones formed in the urinary tract. Affects 10% of men and 7% of women lifetime, often with recurrence. Severe flank pain radiating to groin is the classic presentation; lab workup separates calcium-oxalate (most common) from uric-acid, struvite and cystine subtypes.
ReadICD-10 M35.3Polymyalgia rheumatica (PMR)
Inflammatory disorder of older adults causing severe shoulder and hip-girdle pain and stiffness, especially in the morning. CRP and ESR are sky-high; treatment with low-dose prednisone is dramatically effective — often diagnostic in itself.
ReadICD-10 K50Crohn's disease
Chronic transmural inflammatory bowel disease that can affect anywhere in the GI tract — most often terminal ileum. Causes abdominal pain, diarrhoea, weight loss and extra-intestinal complications. Lifelong, relapsing, but managed effectively with modern biologics.
ReadICD-10 E10Type 1 diabetes (T1D)
Autoimmune destruction of pancreatic insulin-producing beta cells. Onset typically childhood / young adulthood but can present at any age. Lifelong insulin replacement is mandatory — this is not type 2 and oral agents alone do not treat it.
ReadICD-10 G43Migraine
Recurrent attacks of moderate-to-severe headache with nausea, light/sound sensitivity, lasting 4–72 hours. Affects ~14% of adults, women 3× more than men. The lab role is small: rule out anaemia, iron deficiency, thyroid, and (in older onset) inflammatory headache mimics.
ReadICD-10 M32Systemic lupus erythematosus (SLE)
Chronic autoimmune disease in which the immune system attacks the body's own tissues across multiple organ systems. Joints, skin, kidneys, blood cells, brain and heart can all be involved. 9× more common in women; usually onsets ages 15–45.
ReadICD-10 K80Gallstones (cholelithiasis)
Solid concretions of cholesterol or bilirubin that form in the gallbladder. 10–15% of adults in Western populations have them; most stay silent. When they obstruct flow they cause biliary colic, acute cholecystitis, choledocholithiasis, or gallstone pancreatitis.
ReadICD-10 N95.1Menopause & perimenopause
The natural end of ovarian egg supply, confirmed after 12 months without a period — on average at 51. The transition (perimenopause) can last years and brings hot flushes, sleep and mood change, irregular cycles and long-term bone and cardiovascular shifts.
ReadICD-10 E05.0Graves' disease
The most common cause of an overactive thyroid. An autoimmune antibody switches the thyroid permanently 'on', flooding the body with thyroid hormone. It is the hyperthyroid mirror-image of Hashimoto's, and can also affect the eyes.
ReadICD-10 E21.0Primary hyperparathyroidism
An overactive parathyroid gland pushes blood calcium too high. Usually caused by a single benign parathyroid adenoma, it is often silent and found on a routine high-calcium result — but over time it erodes bone and forms kidney stones.
ReadICD-10 E24Cushing's syndrome
Too much cortisol over a long time. Most often it is caused by steroid medication; when it arises inside the body it is usually a pituitary or adrenal tumour. It produces a recognisable picture of central weight gain, a round face, thin skin and high blood pressure.
ReadICD-10 E22.0Acromegaly
Too much growth hormone in adults, almost always from a benign pituitary tumour. It thickens bone and soft tissue slowly over years — enlarging the hands, feet and facial features — so it is often recognised late. IGF-1 is the screening test.
ReadICD-10 M79.7Fibromyalgia
A common condition of widespread body pain, profound fatigue and unrefreshing sleep, thought to reflect how the nervous system processes pain rather than damage in the muscles or joints. Blood tests are normal — their role is to rule out conditions that mimic it.
ReadICD-10 D45Polycythemia vera
A slow-growing blood cancer in which the bone marrow makes too many red cells, thickening the blood and raising the risk of clots. Usually driven by a JAK2 gene mutation, it is picked up from a persistently high haematocrit and haemoglobin.
ReadICD-10 E28.31Primary ovarian insufficiency (POI)
When the ovaries stop working normally before age 40 — irregular or absent periods with a high FSH and low estrogen. Unlike menopause it can fluctuate, and because it removes estrogen's protection early, it needs treatment for bone and heart health.
ReadICD-10 E26.0Primary hyperaldosteronism (Conn's syndrome)
The commonest curable cause of high blood pressure. An adrenal gland makes too much aldosterone, driving up blood pressure and often lowering potassium. It is far more common than once thought and worth screening for in resistant or early-onset hypertension.
ReadICD-10 E03.9Subclinical hypothyroidism
An early, mild form of an underactive thyroid: the TSH is raised but the thyroid hormone (free T4) is still normal. Often symptom-free and found on a routine test, it sometimes needs treatment and sometimes just monitoring.
ReadICD-10 I82.4Deep vein thrombosis (DVT)
A blood clot in a deep vein, usually in the leg. It causes pain and swelling, but the real danger is that part of it can break off and travel to the lungs (pulmonary embolism). Prompt recognition and blood-thinning treatment prevent that.
ReadICD-10 D64.9Anemia
A shortage of healthy red blood cells or the haemoglobin inside them, so blood carries less oxygen. Very common, it is a signpost rather than a diagnosis — the job is to find the cause, and the red-cell size (MCV) is the first clue.
ReadICD-10 D68.61Antiphospholipid syndrome (APS)
An autoimmune condition that makes the blood too likely to clot. It causes blood clots in veins or arteries and, in pregnancy, recurrent miscarriage — driven by antibodies that must be confirmed on two tests 12 weeks apart.
ReadICD-10 E04.1Thyroid nodules
Lumps within the thyroid gland — extremely common and, in the great majority, benign. The evaluation focuses on two questions: is the nodule overactive (making too much hormone), and is there any feature suggesting the small chance of cancer.
ReadICD-10 D51.0Pernicious anemia
The classic autoimmune cause of vitamin B12 deficiency: the immune system attacks the stomach cells that make 'intrinsic factor', the protein needed to absorb B12 from food. It causes a large-cell anaemia and, if untreated, nerve damage — but is very treatable with B12 injections.
ReadICD-10 J30.9Allergic rhinitis (hay fever)
An allergic reaction in the nose to airborne triggers such as pollen, dust mites or pet dander, causing sneezing, a runny or blocked nose and itchy eyes. Extremely common, it is usually diagnosed from the story rather than blood tests.
ReadICD-10 B27.9Infectious mononucleosis (glandular fever)
A common viral infection, usually from the Epstein-Barr virus, causing a prolonged sore throat, fever, swollen glands and marked fatigue — especially in teenagers and young adults. It resolves on its own, but the tiredness can linger for weeks.
ReadICD-10 D70Neutropenia
A low count of neutrophils, the main infection-fighting white cell. Mild neutropenia is often harmless, but a significantly low count weakens defence against bacterial infection — and a low count with a fever, especially after chemotherapy, is a medical emergency.
ReadICD-10 T78.1Food allergy
An immune reaction to a specific food, typically fast and IgE-driven, causing hives, swelling, vomiting or, at its most serious, anaphylaxis. It is distinct from food intolerance, and its diagnosis rests on the story plus specific allergy testing.
ReadICD-10 L20.9Atopic dermatitis (eczema)
A common, chronic, intensely itchy inflammatory skin condition with a relapsing course. It reflects a combination of a leaky skin barrier and an allergic tendency, and it clusters with asthma and hay fever as part of the 'atopic' triad.
ReadICD-10 L50.9Urticaria (hives)
Raised, itchy welts on the skin that come and go, caused by histamine release. Acute hives are common and usually settle within days; chronic hives lasting over six weeks are rarely due to an allergy and are managed mainly with antihistamines.
ReadICD-10 D84.1Hereditary angioedema (HAE)
A rare inherited disorder causing recurrent episodes of deep tissue swelling — of the limbs, face, gut or airway — without the itchy hives of an allergy. It doesn't respond to usual allergy treatments, and a persistently low complement C4 is a key screening clue.
ReadICD-10 E86.0Dehydration
A shortage of body water, from taking in too little or losing too much through vomiting, diarrhoea, sweating or fever. Usually mild and easily corrected by drinking, but severe dehydration strains the kidneys and circulation and can be dangerous, especially in the very young and old.
ReadICD-10 N83.20Ovarian cysts
Fluid-filled sacs on or in an ovary. They are extremely common, most are harmless 'functional' cysts that form with the menstrual cycle and disappear on their own, and the assessment focuses on reassuring the many while identifying the few that need attention.
ReadICD-10 K75.9Hepatitis
Inflammation of the liver, from viruses, alcohol, medications, fat build-up or the immune system. It ranges from a brief, self-limiting illness to a long-term condition that can slowly damage the liver, and it is often silent — picked up on liver blood tests.
ReadICD-10 M19.90Osteoarthritis
The commonest form of arthritis — 'wear and tear' of the joints, where the smooth cartilage cushioning the bone gradually wears down, causing pain and stiffness that worsen with use. Unlike rheumatoid arthritis, blood inflammatory markers are typically normal.
ReadICD-10 G47.33Sleep apnea
Repeated pauses in breathing during sleep, most often because the throat collapses. It causes loud snoring, gasping and unrefreshing sleep with daytime sleepiness, and over time raises the risk of high blood pressure, heart disease and diabetes. It is common, under-diagnosed and very treatable.
ReadICD-10 K29.70Gastritis
Inflammation of the stomach lining, causing upper-tummy pain, nausea and indigestion. The commonest causes are the bacterium Helicobacter pylori and anti-inflammatory painkillers; identifying and treating the cause usually settles it, and left untreated it can lead to ulcers.
ReadICD-10 K58.9Irritable bowel syndrome (IBS)
A very common long-term disorder of how the gut works, causing abdominal pain with bloating and altered bowel habits, without any damage or disease visible in the bowel. It is diagnosed on the symptom pattern once other conditions are excluded, and managed rather than cured.
ReadICD-10 E66.9Obesity
Having enough excess body fat to affect health, usually defined by a body mass index of 30 or above. It is a major driver of type 2 diabetes, high blood pressure, heart disease, sleep apnea, joint problems and some cancers — and even modest weight loss meaningfully improves these risks.
ReadICD-10 E83.0Wilson's disease
A rare inherited disorder in which copper builds up harmfully in the liver and brain because the body cannot get rid of the excess. It usually appears in young people as liver disease or neurological and psychiatric symptoms — and, crucially, it is treatable, so recognising it matters.
ReadICD-10 K85.9Acute pancreatitis
Sudden inflammation of the pancreas, causing severe upper-abdominal pain that bores through to the back, with nausea and vomiting. Most cases are triggered by gallstones or alcohol. It ranges from mild and self-limiting to severe and life-threatening, and is a medical emergency.
ReadICD-10 K37Appendicitis
Inflammation of the appendix, causing pain that classically starts around the navel and shifts to the lower-right abdomen, with loss of appetite, nausea and fever. It is a common surgical emergency, because an untreated inflamed appendix can burst.
ReadICD-10 K57.92Diverticulitis
Inflammation or infection of small pouches (diverticula) that form in the wall of the large bowel, causing lower-left abdominal pain, fever and altered bowel habit. Most cases settle with treatment, but complications like an abscess or perforation can be serious.
ReadICD-10 K81.9Cholecystitis
Inflammation of the gallbladder, almost always because a gallstone blocks its outlet. It causes severe, persistent pain in the upper-right abdomen with fever and nausea — unlike a passing gallstone attack, it does not settle on its own and usually needs treatment.
ReadICD-10 N39.0Urinary tract infection (UTI)
A bacterial infection of the urinary system — most often the bladder (cystitis), causing burning on passing urine, needing to go often and urgently. A kidney infection (pyelonephritis) is more serious, with fever and back pain. UTIs are very common and usually treatable.
ReadICD-10 D59.9Hemolytic anemia
Anemia caused by red blood cells being destroyed faster than the marrow can replace them. It produces a characteristic blood pattern — high LDH and bilirubin, low haptoglobin, and a rise in young red cells — often with jaundice and dark urine.
ReadICD-10 N41.9Prostatitis
Inflammation of the prostate gland in men, causing pelvic or genital pain, urinary symptoms and sometimes fever. Acute bacterial prostatitis is a sudden, feverish infection needing prompt antibiotics; the chronic form is a common, often frustrating cause of long-term pelvic discomfort.
ReadICD-10 A41.9Sepsis
A life-threatening emergency in which the body's response to an infection injures its own tissues and organs. It can develop from any infection and progresses fast, so recognising the warning signs and getting emergency treatment quickly saves lives.
ReadICD-10 E10.10Diabetic ketoacidosis (DKA)
A dangerous diabetes emergency in which a lack of insulin makes blood sugar soar and the body burn fat, flooding the blood with acidic ketones. It causes thirst, vomiting, deep rapid breathing and drowsiness, and needs urgent hospital treatment — it can be life-threatening.
ReadICD-10 E87.1Hyponatremia (low sodium)
A lower-than-normal blood sodium level, most often caused by too much water relative to salt rather than a lack of salt. Mild cases are common and symptomless; a severe or rapidly falling sodium can cause confusion and seizures, and correction must be done carefully.
ReadICD-10 C90.00Multiple myeloma
A cancer of plasma cells — the antibody-making cells in the bone marrow. It often shows up through its effects, summarised as 'CRAB': raised calcium, kidney impairment, anaemia and bone damage. It is not curable but is very treatable, and treatment has improved greatly.
ReadICD-10 I50.9Heart failure
A condition where the heart cannot pump blood as effectively as the body needs, causing fluid to build up and less oxygen to reach the tissues. It brings breathlessness, tiredness and swollen ankles. It is long-term but very treatable, and modern treatment greatly improves symptoms and outlook.
ReadICD-10 I48.91Atrial fibrillation
The commonest abnormal heart rhythm, in which the upper chambers of the heart beat in a fast, disorganised way, making the pulse irregular. It may cause palpitations, breathlessness or tiredness, or none at all — and its main danger is a raised risk of stroke, which treatment can greatly reduce.
ReadICD-10 I26.99Pulmonary embolism
A blood clot that has travelled to the lungs and blocked one of their arteries, usually after breaking off from a clot in a leg vein. It typically causes sudden breathlessness, chest pain and a fast heart rate, and is a medical emergency — but it is treatable, and prompt treatment is life-saving.
ReadICD-10 K27.9Peptic ulcer disease
An open sore in the lining of the stomach or the first part of the small intestine (duodenum), where stomach acid has eroded the protective lining. The main causes are Helicobacter pylori infection and anti-inflammatory painkillers. It typically causes burning upper-abdominal pain and can bleed.
ReadICD-10 K51.90Ulcerative colitis
A long-term inflammatory bowel disease in which the lining of the large intestine (colon) and rectum becomes inflamed and ulcerated. It causes bouts of bloody diarrhoea, urgency and abdominal pain, running a relapsing-remitting course, and is treated to control inflammation and keep it in remission.
ReadICD-10 K74.3Primary biliary cholangitis (PBC)
A long-term autoimmune liver disease in which the immune system slowly damages the small bile ducts inside the liver, causing bile to build up. It often shows first as fatigue and itching with a raised alkaline phosphatase, and is strongly linked to a specific autoantibody (anti-mitochondrial antibody).
ReadICD-10 C85.90Lymphoma
A cancer of the lymphatic system — the network of lymph nodes and lymphocytes that is part of the immune system. It often shows up as painless swollen lymph nodes, sometimes with fevers, night sweats and weight loss. Many types are highly treatable, and some are curable.
ReadICD-10 C73Thyroid cancer
A cancer arising in the thyroid gland, usually found as a lump or nodule in the neck. Most types — especially the common papillary form — grow slowly and have an excellent outlook with treatment. Specific blood markers (thyroglobulin, calcitonin) are used mainly to monitor after treatment.
ReadICD-10 C95.90Leukemia
A cancer of the blood-forming cells in the bone marrow, in which abnormal white cells crowd out normal blood production. It can cause tiredness and pallor from anaemia, infections from a lack of healthy white cells, and bruising or bleeding from low platelets. Many forms are treatable.
ReadICD-10 I77.6Vasculitis
Inflammation of blood vessels, which damages their walls and disrupts blood flow to organs. It ranges from mild, skin-only forms to serious diseases affecting the kidneys, lungs and nerves. Early diagnosis and treatment matter, as some types can cause rapid organ damage.
ReadICD-10 K75.4Autoimmune hepatitis
A chronic disease in which the immune system attacks the liver, causing ongoing inflammation and, if untreated, scarring. It often shows up as raised liver enzymes with autoantibodies and a high IgG, and it usually responds well to treatment that calms the immune system.
ReadICD-10 E25.0Congenital adrenal hyperplasia (CAH)
An inherited group of conditions in which an enzyme needed to make cortisol in the adrenal glands is deficient. This lowers cortisol, drives up 17-hydroxyprogesterone, and diverts the pathway into making excess androgens. Severity ranges from a newborn emergency to a milder adult form.
ReadICD-10 I25.10Coronary artery disease (CAD)
A gradual furring and narrowing of the arteries that supply the heart with blood, driven by cholesterol plaque. It can cause chest pain on exertion (angina), and its most dangerous complication — when a plaque ruptures — is a heart attack. Risk is largely modifiable.
ReadICD-10 I21.9Myocardial infarction (heart attack)
A heart attack: part of the heart muscle is starved of blood, usually because a cholesterol plaque in a coronary artery ruptures and a clot blocks it. It causes severe chest pain and is a medical emergency — fast treatment to restore blood flow saves heart muscle and lives.
ReadICD-10 I73.9Peripheral artery disease (PAD)
Narrowing of the arteries that supply the legs (and sometimes arms) with blood, from the same plaque process behind heart disease. Its hallmark is leg pain on walking that eases with rest (claudication). It also signals high risk of heart attack and stroke.
ReadICD-10 D66Hemophilia
An inherited bleeding disorder in which a clotting factor is missing or low, so blood does not clot properly. It causes easy bruising and bleeding — classically into joints and muscles — and, in severe cases, spontaneous bleeds. It is treated by replacing the missing factor, and most people live full lives.
ReadICD-10 D68.0Von Willebrand disease
The most common inherited bleeding disorder, caused by a lack or fault of von Willebrand factor — a protein that helps platelets stick and stabilises factor VIII. It causes easy bruising, nosebleeds, heavy periods and prolonged bleeding after surgery, and is usually mild.
ReadICD-10 D65Disseminated intravascular coagulation (DIC)
A serious, always-secondary condition in which clotting is switched on throughout the body at once. It uses up platelets and clotting factors, so tiny clots form in small vessels while, paradoxically, dangerous bleeding occurs elsewhere. It is a medical emergency driven by another severe illness.
ReadICD-10 B18.1Hepatitis B
A viral infection of the liver caused by the hepatitis B virus, spread through blood and bodily fluids. Many acute infections clear on their own, but some become chronic and, over years, can damage the liver. It is preventable by vaccination and, when chronic, very treatable — living well with it is the norm.
ReadICD-10 B18.2Hepatitis C
A viral infection of the liver caused by the hepatitis C virus, spread mainly through blood. It often causes no symptoms and can quietly become chronic over years, damaging the liver. The transformative news is that hepatitis C is now curable in the large majority of people with a short course of antiviral tablets.
ReadICD-10 B20HIV infection
An infection with the human immunodeficiency virus (HIV), which over time can weaken the immune system if untreated. The picture today is very different from the past: with modern treatment, HIV is a manageable long-term condition, people live long healthy lives, and effective treatment prevents passing it on.
ReadICD-10 N17.9Acute kidney injury (AKI)
A sudden drop in kidney function over hours to days, so the kidneys can no longer clear waste and balance fluids and salts properly. It is often triggered by dehydration, infection, low blood pressure or certain medicines, and is usually reversible if the cause is treated quickly.
ReadICD-10 N04.9Nephrotic syndrome
A kidney disorder in which the filters leak large amounts of protein into the urine, causing the blood protein albumin to fall and fluid to build up as swelling. It comes with heavy proteinuria, low albumin, swelling and often high cholesterol, and needs specialist investigation and treatment.
ReadICD-10 N05.9Glomerulonephritis
Inflammation of the tiny filters of the kidney (the glomeruli), which damages their ability to filter blood cleanly. It causes blood and protein to leak into the urine and can reduce kidney function; it ranges from mild and self-limiting to serious, and often needs specialist care.
ReadICD-10 D56.9Thalassemia
An inherited condition in which the body makes less of one of the haemoglobin chains, leading to small, pale red cells and anaemia. It ranges from a harmless carrier state (trait) that causes only a mild anaemia to a severe form needing lifelong transfusions.
ReadICD-10 D57.1Sickle cell disease
An inherited disorder in which an abnormal haemoglobin makes red cells stiffen into a sickle shape. These cells break down early and block small blood vessels, causing anaemia and episodes of severe pain, and needing lifelong specialist care.
ReadICD-10 D55.0G6PD deficiency
An inherited enzyme shortage that leaves red blood cells vulnerable to certain triggers — some medicines, infections and foods (notably fava beans). When triggered, red cells break down suddenly, causing an episode of anaemia and jaundice; between episodes people are usually well.
ReadICD-10 M34.9Scleroderma (systemic sclerosis)
An autoimmune connective-tissue disease in which the body lays down too much collagen, thickening and tightening the skin and, in the systemic form, scarring internal organs such as the lungs, kidneys and gut. Raynaud's phenomenon is often the first sign; care focuses on protecting organs.
ReadICD-10 M33.1Dermatomyositis
An autoimmune disease that inflames the muscles and skin, causing weakness of the muscles closest to the trunk (shoulders and hips) together with a distinctive rash. Blood tests show raised muscle enzymes; it needs specialist care, and in adults it prompts a search for an associated cancer.
ReadICD-10 M35.1Mixed connective-tissue disease (MCTD)
An autoimmune 'overlap' disease that combines features of lupus, scleroderma and inflammatory muscle disease, defined by a high level of anti-U1-RNP antibody. Raynaud's phenomenon and puffy fingers are typical early signs; it needs specialist care and monitoring of the lungs.
ReadICD-10 C50.9Breast cancer
The most common cancer in women, in which cells in the breast grow abnormally. Most breast lumps are not cancer, and when breast cancer is found early it is very often treatable. Screening, prompt assessment of any change and modern treatment mean outcomes today are good for many people.
ReadICD-10 C18.9Colorectal (bowel) cancer
A cancer of the large bowel (colon or rectum), among the most common cancers but also one of the most preventable and treatable when found early. It usually grows slowly from benign polyps, which screening can detect and remove — and early bowel cancer is very often curable.
ReadICD-10 C34.90Lung cancer
A cancer that begins in the lungs, most often linked to smoking but also occurring in people who have never smoked. Caught early it can be treated effectively, and screening for people at higher risk, plus prompt assessment of persistent chest symptoms, help find it sooner.
ReadICD-10 D35.00Pheochromocytoma
A rare, usually benign tumour of the adrenal gland that pours out the 'fight-or-flight' hormones adrenaline and noradrenaline. It causes spells of severe high blood pressure with headache, sweating, a pounding heart and pallor, and is important because it is dangerous but often curable with surgery.
ReadICD-10 D35.2Prolactinoma
A benign tumour of the pituitary gland that makes too much of the hormone prolactin. It can cause milky breast discharge, irregular or absent periods and low fertility in women, and low libido and erectile problems in men, and large tumours can press on nearby structures. It is usually very treatable with tablets.
ReadICD-10 E23.2Diabetes insipidus
A disorder of water balance — unrelated to sugar diabetes — in which the body cannot concentrate urine properly, so it passes large volumes of dilute urine and is driven to drink constantly. It is caused by a problem with the hormone that tells the kidneys to retain water, or with the kidneys' response to it.
ReadICD-10 M83.9Osteomalacia
A condition where bones become soft because the bone tissue does not mineralise properly, usually from a lack of vitamin D. It causes bone pain, muscle weakness and a higher risk of fractures, and — unlike osteoporosis — is often very treatable by correcting the underlying deficiency.
ReadICD-10 M88.9Paget's disease of bone
A chronic disorder in which the normal recycling of bone becomes overactive and disorganised, so affected bones are remodelled too fast and end up enlarged, misshapen and weaker. Many people have no symptoms; others have bone pain, deformity or fractures. It is usually treatable.
ReadICD-10 M85.80Osteopenia
Bone density that is lower than normal but not low enough to be called osteoporosis. It is a milder, earlier stage of bone thinning that raises fracture risk somewhat and is a signal to protect the bones with lifestyle measures — and sometimes treatment — to stop it progressing.
ReadICD-10 E52Pellagra (niacin deficiency)
A disease caused by severe lack of vitamin B3 (niacin), remembered by the 'three D's': dermatitis, diarrhoea and dementia. Once common where maize-based diets predominated, it is now seen mainly with alcohol dependence, malabsorption or severe malnutrition, and it responds quickly to niacin.
ReadICD-10 E54Scurvy (vitamin C deficiency)
A disease caused by prolonged lack of vitamin C, which the body needs to make collagen. It causes bleeding, swollen and bleeding gums, easy bruising, poor wound healing, and tiredness. Once the scourge of sailors, it still occurs today with very poor diets and responds rapidly to vitamin C.
ReadICD-10 E01.8Iodine deficiency
A shortage of dietary iodine, the raw material the thyroid needs to make its hormones. It is the world's leading preventable cause of goitre and an underactive thyroid, and in pregnancy it can harm the baby's brain development. Salt iodisation has reduced it, but mild deficiency persists.
ReadICD-10 E87.5Hyperkalemia (high potassium)
A higher-than-normal level of potassium in the blood. Potassium is essential for the heart's rhythm, so a severely high level is dangerous — it can cause a life-threatening irregular heartbeat. It is often caused by kidney problems or certain medications, and severe cases are an emergency.
ReadICD-10 E87.6Hypokalemia (low potassium)
A lower-than-normal level of potassium in the blood. Because potassium keeps the heart and muscles working normally, a low level can cause muscle weakness, cramps and — when severe — dangerous heart-rhythm problems. It is often caused by fluid loss, diuretic medications or vomiting and diarrhoea.
ReadICD-10 E83.52Hypercalcemia (high calcium)
A higher-than-normal level of calcium in the blood. Mild cases often cause no symptoms and are found on a routine test; higher levels cause thirst, frequent urination, constipation, tiredness and confusion. The two commonest causes are an overactive parathyroid gland and, importantly, some cancers.
ReadICD-10 D25.9Uterine fibroids
Common, non-cancerous growths of muscle in the wall of the womb. Many cause no symptoms, but larger or multiple fibroids can cause heavy periods, pelvic pressure and pain, and sometimes anaemia from blood loss or problems with fertility and pregnancy.
ReadICD-10 N94.3Premenstrual syndrome (PMS / PMDD)
A cluster of physical and emotional symptoms that appear in the days before a period and settle once it starts. Common ones include mood changes, irritability, bloating, breast tenderness and tiredness. When mood symptoms are severe, it is called premenstrual dysphoric disorder (PMDD).
ReadICD-10 E29.1Hypogonadism
A condition in which the ovaries or testes make too little of their sex hormones — estrogen in women, testosterone in men. It causes symptoms such as low libido, fatigue, infertility, and in women irregular or absent periods, and can arise from the gonads themselves or from the pituitary gland that controls them.
ReadICD-10 B25.9Cytomegalovirus infection (CMV)
Infection with cytomegalovirus, a very common herpesvirus. In healthy people it usually causes no symptoms or a mild mono-like illness and then lies dormant for life. It matters most in pregnancy (it can affect the baby) and in people with weakened immunity, where it can cause serious disease.
ReadICD-10 A15.9Tuberculosis (TB)
A bacterial infection, usually of the lungs, caused by Mycobacterium tuberculosis. It can lie dormant (latent TB) or become active disease, causing a persistent cough, fever, night sweats and weight loss. It is treatable and curable with a course of antibiotics, but needs prompt diagnosis.
ReadICD-10 U07.1COVID-19
An illness caused by the SARS-CoV-2 coronavirus, ranging from a mild cold-like or flu-like illness to, in some people, severe pneumonia. Most cases are mild and self-limiting; older people and those with certain conditions are at higher risk of serious disease.
ReadICD-10 M45Ankylosing spondylitis
A chronic inflammatory arthritis that mainly affects the spine and the joints where the pelvis meets the spine. It causes gradual-onset back pain and stiffness that is worse with rest and better with movement, typically starting in young adulthood, and can, over years, fuse parts of the spine.
ReadICD-10 L40.5Psoriatic arthritis
An inflammatory arthritis that occurs in some people with the skin condition psoriasis. It causes painful, swollen and stiff joints — sometimes with swelling of a whole finger or toe, nail changes and back involvement — and, like other inflammatory arthritis, benefits from early treatment.
ReadICD-10 M31.6Giant cell arteritis
An inflammation of medium and large arteries, especially those around the temples and head, occurring in older adults. It causes a new headache, scalp tenderness and jaw pain, and can threaten vision — so suspected cases need urgent assessment and treatment to protect eyesight.
ReadICD-10 C61Prostate cancer
One of the commonest cancers in men, arising in the prostate gland. Many prostate cancers grow slowly and never cause harm, while some are more aggressive. It is often found through a raised PSA blood test, and there are effective treatments — as well as, for low-risk cases, careful monitoring.
ReadICD-10 C16.9Gastric cancer (stomach cancer)
A cancer that develops in the lining of the stomach. It often causes vague digestive symptoms at first — indigestion, feeling full quickly, or discomfort — which is why it can be found late. Long-term Helicobacter pylori infection is an important, treatable risk factor.
ReadICD-10 C43.9Melanoma
The most serious form of skin cancer, arising from the pigment-producing cells of the skin. It often shows as a new or changing mole. Caught early, it is usually curable by removing it — which is why recognising a changing mole and getting it checked matters so much.
ReadICD-10 E34.0Carcinoid syndrome
A cluster of symptoms — flushing, diarrhoea and sometimes wheezing — caused by a neuroendocrine (carcinoid) tumour releasing serotonin and other chemicals into the blood. It usually appears once the tumour has spread to the liver, and is diagnosed with urine 5-HIAA and chromogranin A.
ReadICD-10 E16.4Zollinger-Ellison syndrome
A rare condition in which a tumour (a gastrinoma) produces the hormone gastrin uncontrollably, driving the stomach to make far too much acid. The result is severe, multiple or recurrent peptic ulcers and diarrhoea. It is diagnosed with a very high fasting gastrin alongside an acidic stomach.
ReadICD-10 D13.7Insulinoma
A rare, usually benign pancreatic tumour that produces insulin uncontrollably, causing repeated episodes of low blood sugar. Symptoms — shakiness, sweating, dizziness, confusion — appear when fasting or before meals and ease with eating. It is diagnosed by measuring insulin and glucose together during a low.
ReadICD-10 D61.9Aplastic anemia
A rare but serious condition in which the bone marrow fails to make enough new blood cells, so all three types fall — red cells, white cells and platelets. This causes tiredness and pallor, frequent infections, and easy bruising or bleeding, and it needs specialist haematology care.
ReadICD-10 D46.9Myelodysplastic syndrome (MDS)
A group of bone-marrow disorders in which the marrow makes blood cells that are abnormal (dysplastic) and don't work properly, so blood counts fall despite a busy marrow. Mostly affecting older adults, MDS causes anaemia and low counts and carries a risk of progressing to leukaemia.
ReadICD-10 D47.4Myelofibrosis
A rare bone-marrow disorder in which the marrow becomes progressively scarred (fibrosed), crowding out normal blood-cell production. Blood cells then get made in the spleen and liver, which enlarge. It causes anaemia, an enlarged spleen, and characteristic teardrop-shaped red cells on the blood film.
ReadICD-10 D68.59Thrombophilia
An increased tendency to form abnormal blood clots, either inherited or acquired. It does not cause clots by itself but raises the risk, especially in situations like surgery, pregnancy or immobility. It is investigated after an unexplained or recurrent clot, and most people with it never have a major problem.
ReadICD-10 D69.6Thrombocytopenia (low platelets)
A lower-than-normal platelet count. Platelets help the blood clot, so a low count can cause easy bruising, bleeding gums, nosebleeds and, if very low, more serious bleeding. Causes range from harmless or temporary to serious, and the count and the cause together determine how much it matters.
ReadICD-10 D75.839Thrombocytosis (high platelets)
A higher-than-normal platelet count. Most cases are 'reactive' — the platelets rise temporarily in response to something else, such as infection, inflammation, iron deficiency or recent surgery — and settle. Less often it reflects a bone-marrow disorder, so a persistently high count is worth investigating.
ReadICD-10 E23.0Hypopituitarism
An underactive pituitary gland that fails to make enough of one or more of its hormones. Because the pituitary directs the thyroid, adrenal glands and sex glands, symptoms are varied — tiredness, low libido, cold intolerance — and can be serious if the cortisol-driving hormone is affected.
ReadICD-10 D35.2Pituitary adenoma
A benign (non-cancerous) growth on the pituitary gland at the base of the brain. Some make excess hormones, causing distinctive syndromes; others are 'silent' but grow large enough to press on the gland or nearby nerves, causing headaches, visual loss and hormone deficiency.
ReadICD-10 E22.1Hyperprolactinemia
A higher-than-normal level of prolactin, the hormone that drives breast milk production. It can cause milky discharge, loss of periods, low libido and infertility. Causes range from harmless (pregnancy, medications) to a pituitary tumour, so a raised prolactin is worth investigating.
ReadICD-10 A53.9Syphilis
A sexually transmitted infection caused by the bacterium Treponema pallidum. It progresses through stages — starting with a painless sore, then a body rash, then, if untreated for years, serious damage to the heart, brain and nerves. It is fully curable with antibiotics when caught, and blood tests screen for it.
ReadICD-10 A69.20Lyme disease
A bacterial infection spread by the bite of an infected tick. It often starts with an expanding 'bull's-eye' rash and flu-like symptoms; if untreated it can later affect the joints, nervous system and heart. Caught early, it is treated effectively with antibiotics.
ReadICD-10 I00Rheumatic fever
A delayed inflammatory reaction that can follow an untreated strep throat, usually in children. The immune response mistakenly attacks the body's own tissues, causing fever, migrating joint pains, and — most seriously — inflammation of the heart that can leave lasting valve damage.
ReadICD-10 I42.9Cardiomyopathy
A group of diseases of the heart muscle itself, in which the muscle becomes enlarged and weak, abnormally thickened, or stiff. It can cause breathlessness, swelling, palpitations and fatigue, and in some forms carries a risk of dangerous rhythm problems. Care aims to relieve symptoms and reduce risk.
ReadICD-10 I30.9Pericarditis
Inflammation of the pericardium, the thin sac surrounding the heart. It typically causes sharp chest pain that is worse lying down and better sitting forward, often after a viral infection. Most cases settle with anti-inflammatory treatment, but the chest pain always needs assessment to exclude a heart attack.
ReadICD-10 E78.1Hypertriglyceridemia
A raised level of triglycerides, a type of fat, in the blood. Mild-to-moderate elevation adds to cardiovascular risk and often accompanies diabetes and metabolic syndrome; very high levels can inflame the pancreas. It is usually managed with diet, exercise, controlling related conditions and sometimes medication.
ReadICD-10 E73.9Lactose intolerance
Difficulty digesting lactose, the sugar in milk, because the gut makes too little of the enzyme lactase. Undigested lactose causes bloating, wind, cramps and diarrhoea after dairy. It is common, harmless in itself, and managed by limiting lactose rather than with medication.
ReadICD-10 K63.821Small intestinal bacterial overgrowth (SIBO)
A condition in which too many bacteria grow in the small intestine, where numbers are normally low. The bacteria ferment food and interfere with absorption, causing bloating, wind, discomfort and sometimes diarrhoea and nutrient deficiencies. It is treated mainly with antibiotics and by tackling the cause.
ReadICD-10 K31.84Gastroparesis
A condition in which the stomach empties too slowly even though there is no blockage. Food lingers, causing nausea, vomiting, feeling full very quickly, bloating and upper-abdominal discomfort. Diabetes is a common cause, and it is managed with diet, medication to aid emptying, and blood-sugar control.
ReadICD-10 E51.11Beriberi (thiamine deficiency)
The disease caused by a lack of vitamin B1 (thiamine). 'Dry' beriberi damages the nerves, causing weakness and tingling in the legs; 'wet' beriberi strains the heart, causing swelling and breathlessness. It is treatable — and rapidly reversible — with thiamine.
ReadICD-10 E55.0Rickets
A childhood disease in which growing bones fail to harden properly, usually from a lack of vitamin D (and the calcium and phosphate it controls). It causes soft, weak and deformed bones — classically bowed legs — and is prevented and treated with vitamin D and calcium.
ReadICD-10 E87.8Refeeding syndrome
A dangerous shift in body chemistry that can occur when a severely malnourished person is fed again too quickly. Phosphate, potassium and magnesium plummet as the body switches back to using food, which can cause heart, breathing and nerve problems — it can be life-threatening.
ReadICD-10 K83.01Primary sclerosing cholangitis (PSC)
A chronic disease in which the bile ducts inside and outside the liver become inflamed and scarred, narrowing and blocking the flow of bile. It develops slowly, is strongly linked to inflammatory bowel disease, and can progress over years to cirrhosis; it also raises the risk of bile-duct cancer.
ReadICD-10 D89.831IgG4-related disease
An uncommon disease in which the immune system drives inflammation and scarring that can affect many organs — classically the pancreas, bile ducts and salivary glands — often forming tumour-like swellings. A raised blood IgG4 supports it, and it usually responds well to treatment with steroids.
ReadICD-10 K72.90Hepatic encephalopathy
A disturbance of brain function caused by liver failure, in which toxins the liver would normally clear — especially ammonia — build up and affect the brain. It ranges from subtle confusion and drowsiness to a characteristic hand-flap and, at its most severe, coma, and needs prompt treatment.
ReadICD-10 Q61.2Polycystic kidney disease (PKD)
An inherited condition in which many fluid-filled cysts grow in the kidneys over years, enlarging them and slowly reducing their function. It often causes high blood pressure, back or side pain, and blood in the urine, and can eventually lead to kidney failure.
ReadICD-10 N02.8IgA nephropathy
The most common form of glomerulonephritis, in which an antibody called IgA builds up in the kidney's filters and inflames them. It often shows up as blood in the urine — sometimes visible during a cold — and, over years, can slowly damage the kidneys.
ReadICD-10 E11.21Diabetic nephropathy
Kidney damage caused by long-standing diabetes, in which high blood sugar over years harms the kidney's filters. It is a leading cause of kidney failure, usually silent at first and detected by finding small amounts of protein (albumin) leaking into the urine.
ReadICD-10 N25.89Renal tubular acidosis (RTA)
A group of conditions in which the kidney's tubules cannot properly handle acid, so the blood becomes mildly acidic even though the kidney's filtering is normal. It can disturb potassium levels, weaken bones, and cause kidney stones, and is treated by correcting the acid.
ReadICD-10 I63.9Stroke
A medical emergency in which the blood supply to part of the brain is suddenly cut off — usually by a clot, sometimes by a bleed — starving brain cells of oxygen. It causes sudden face drooping, arm weakness or speech trouble, and needs immediate treatment: every minute counts.
ReadICD-10 G35Multiple sclerosis (MS)
A condition in which the immune system attacks the protective coating around nerves in the brain and spinal cord, disrupting the signals they carry. It causes varied symptoms — vision problems, numbness, weakness, balance trouble — that often come and go in relapses over years.
ReadICD-10 G20Parkinson's disease
A progressive brain condition in which cells that make dopamine are gradually lost, causing a resting tremor, slowness of movement, and stiffness. It develops slowly over years, usually in older adults, and while there is no cure, treatment can control symptoms well.
ReadICD-10 G70.00Myasthenia gravis
An autoimmune condition in which antibodies disrupt the signal between nerves and muscles, causing muscle weakness that gets worse with use and better with rest. It typically affects the eyes, face, throat and limbs, and is confirmed largely by an antibody blood test.
ReadICD-10 J44.9COPD (chronic obstructive pulmonary disease)
A long-term lung disease, usually caused by smoking, in which the airways become narrowed and the lung tissue damaged, making it progressively harder to breathe out. It causes breathlessness, a persistent cough with phlegm and frequent chest infections, and is diagnosed by a breathing test.
ReadICD-10 J18.9Pneumonia
An infection of the lung tissue, usually caused by bacteria or viruses, in which the tiny air sacs fill with fluid and inflammation. It causes cough, fever, breathlessness and chest pain, and ranges from a mild illness treated at home to a severe one needing hospital care.
ReadICD-10 D86.9Sarcoidosis
An inflammatory disease in which small clusters of immune cells (granulomas) form in the body, most often the lungs and lymph nodes. Many cases are mild and settle on their own, but it can affect other organs and cause a persistent cough, breathlessness, fatigue and raised calcium.
ReadICD-10 J84.10Pulmonary fibrosis
A condition in which the lung tissue becomes progressively scarred and stiff, making it harder to expand and to move oxygen into the blood. It causes gradually worsening breathlessness and a persistent dry cough, and needs specialist assessment to find the cause and slow it.
ReadICD-10 M02.9Reactive arthritis
Joint inflammation that develops as a reaction to an infection elsewhere in the body — typically a gut or genital infection — a week or two earlier. It usually affects the knees, ankles and feet, can involve the eyes and urinary tract, and most often settles over months.
ReadICD-10 M35.2Behçet's disease
A rare, long-term inflammatory condition that inflames blood vessels throughout the body. Its hallmark is recurrent painful mouth ulcers, often with genital ulcers, eye inflammation and skin lesions, coming in flares. It is most common along the historic Silk Road, and needs specialist care.
ReadICD-10 T78.2Anaphylaxis
A severe, rapidly developing allergic reaction that is a medical emergency. Triggered by foods, insect stings, medicines or other allergens, it can cause breathing difficulty, throat swelling, a widespread rash and a drop in blood pressure. It is treated immediately with adrenaline (epinephrine).
ReadICD-10 Q82.2Mastocytosis
A rare condition in which the body has too many mast cells — the immune cells that release histamine — either in the skin alone or throughout the body. It causes flushing, itching, hives, gut symptoms and, at worst, severe reactions, and is signalled by a persistently raised tryptase.
ReadICD-10 B02.9Shingles (herpes zoster)
A painful, blistering rash caused by reactivation of the chickenpox virus, which lies dormant in nerves after childhood chickenpox. It typically appears as a band of rash on one side of the body and can leave lingering nerve pain; a vaccine helps prevent it in older adults.
ReadICD-10 G03.9Meningitis
Inflammation of the membranes covering the brain and spinal cord, most often from infection. Bacterial meningitis is a life-threatening emergency causing fever, severe headache, a stiff neck and sometimes a rash — it needs immediate hospital treatment. Viral meningitis is usually milder.
ReadICD-10 L03.90Cellulitis
A common bacterial infection of the skin and the soft tissue just beneath it, causing an area of skin that is red, warm, swollen and tender — usually on a leg. It spreads if untreated, so it needs antibiotics; a rapidly spreading or severely painful case needs urgent care.
ReadICD-10 J03.90Tonsillitis
Inflammation of the tonsils — the two soft-tissue pads at the back of the throat — usually from a viral or bacterial infection. It causes a sore throat, painful swallowing, swollen tonsils and often fever. Most cases are viral and settle on their own; some bacterial cases need antibiotics.
ReadICD-10 E16.2Hypoglycemia (low blood sugar)
A blood sugar level low enough to cause symptoms — shakiness, sweating, hunger, palpitations and, if it falls further, confusion. It is most common in people with diabetes on treatment, but rarer causes exist. A severe episode is an emergency that needs fast-acting sugar.
ReadICD-10 E22.2SIADH (syndrome of inappropriate antidiuretic hormone)
A condition in which the body releases too much of the water-retaining hormone ADH, so the kidneys hold on to water and dilute the blood — causing a low sodium. It is a common cause of low sodium, often from medications, lung or brain problems, or cancer, and is worked out with blood and urine tests.
ReadICD-10 I16.9Hypertensive crisis
A severe, sudden rise in blood pressure — usually a top number above 180 or bottom above 120 — that can damage organs. It is an emergency: with signs of harm to the brain, heart, kidneys or eyes it needs immediate hospital care, and even without them it needs urgent attention.
ReadICD-10 I15.9Secondary hypertension
High blood pressure caused by an identifiable, often treatable, underlying condition — rather than the common 'essential' kind with no single cause. It is suspected when high blood pressure appears young, is very severe or hard to control, and is worked up with targeted blood, urine and imaging tests.
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