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.
What it is
Iron-deficiency anaemia (IDA) develops when the body can't produce enough functional haemoglobin because iron stores are depleted. Iron is needed to build haemoglobin, the oxygen-carrying protein in red blood cells. Stores deplete gradually — first ferritin drops, then transferrin saturation falls, then the haemoglobin level itself begins to decline. WHO defines anaemia as haemoglobin <13 g/dL in men, <12 g/dL in non-pregnant women, <11 g/dL in pregnant women.
Key lab markers
- Ferritin — the earliest sign of depleting iron stores; values <30 ng/mL suggest deficiency before haemoglobin falls.
- Haemoglobin — anaemia by WHO definition.
- MCV — microcytic (low MCV) anaemia is the classic IDA picture.
- Transferrin saturation — typically <16% in active deficiency.
Symptoms
- Fatigue and reduced exercise tolerance
- Pallor, especially of the conjunctiva
- Brittle nails, hair loss
- Restless legs at night
- Pica (cravings for ice, clay)
- Glossitis (smooth, sore tongue) in advanced cases
When to discuss with a doctor
Suspected IDA needs a primary-care visit. Treatment is straightforward (oral iron in most cases), but identifying the SOURCE of iron loss is the critical step — heavy menstrual bleeding, pregnancy, gastrointestinal bleeding (peptic ulcer, colorectal cancer), or malabsorption. Adult-onset IDA without obvious cause warrants a GI evaluation.