Hemoglobin
Hemoglobin is the oxygen-carrying protein inside red blood cells. A low value defines anaemia.
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What it measures
Hemoglobin binds oxygen in the lungs and releases it to tissues — a single hemoglobin molecule can carry four oxygen molecules. The blood concentration of hemoglobin, alongside red blood cell count and hematocrit, is the central anaemia work-up: WHO defines anaemia as Hb <13 g/dL in men, <12 g/dL in non-pregnant women, <11 g/dL in pregnant women. The why of low Hb — iron, B12/folate, chronic inflammation, bone-marrow disease, blood loss — needs additional markers to tease apart.
What a high value can mean
- Dehydration — concentrates the blood.
- Chronic hypoxia — smokers, COPD, sleep apnoea, high-altitude residence.
- Polycythaemia vera — bone-marrow disorder; usually paired with high platelets and white cells.
- Erythropoietin abuse / certain tumours — rare.
What a low value can mean
- Iron-deficiency anaemia — most common cause; check ferritin.
- Anaemia of chronic disease — inflammation, kidney failure, malignancy.
- Vitamin B12 / folate deficiency — macrocytic anaemia.
- Acute or chronic blood loss — menstrual, gastrointestinal.
- Hemolytic anaemia — sickle cell, autoimmune.
When to discuss with a doctor
Hb below 10 g/dL warrants a focused medical evaluation; <7 g/dL is the transfusion-consideration zone and needs urgent assessment. Hb >18 g/dL alongside symptoms (headache, dizziness, ruddy face) also warrants prompt workup. Mediora.AI flags critical Hb values directly inside your report.