Itching (pruritus)

Pruritus is the medical term for itching. With an obvious skin rash the cause is usually dermatological (eczema, psoriasis, scabies, contact dermatitis). Without a rash — or with only secondary excoriations from scratching — the differential turns to systemic disease: cholestatic liver disease, chronic kidney disease (uraemic pruritus), iron-deficiency anaemia, polycythaemia vera, thyroid dysfunction (both hyper and hypo), HIV, lymphoma (especially Hodgkin's, sometimes weeks before other symptoms), and certain medications (opioids, anti-malarials, statins). Generalized itching that wakes the patient at night is more concerning for systemic disease than localized daytime itching.

• Dry skin (xerosis) — extremely common in older adults; usually responds to moisturizers.
• Eczema, psoriasis, scabies, contact dermatitis — dermatological; rash usually visible.
• Cholestatic liver disease — primary biliary cholangitis, primary sclerosing cholangitis, drug-induced cholestasis; bile salts deposit in skin.
• Chronic kidney disease (uraemic pruritus) — common in dialysis patients; mechanism not fully understood.
• Iron-deficiency anaemia — itching mostly on the legs and trunk.
• Polycythaemia vera — classically itching after a hot shower (aquagenic pruritus).
• Hyperthyroidism, hypothyroidism — both can drive pruritus.
• Lymphoma, especially Hodgkin's — can precede other symptoms by months; often with night sweats and weight loss.
• Medications — opioids, statins, anti-malarials, ACE inhibitors.
• Pregnancy — third-trimester cholestasis is a defined entity.

First-line: liver panel (bilirubin, ALP, GGT, ALT, AST), full metabolic panel (creatinine, eGFR), TSH, CBC + ferritin, glucose, HIV test if epidemiologically reasonable. Add abdominal ultrasound if cholestatic pattern, peripheral smear if polycythaemia or lymphoma suspected. Mediora.AI surfaces the systemic patterns; biopsy and rash-focused work-up belong with dermatology.