Iron → Haemoglobin → Oxygen Delivery → Energy
The biology
Iron is built into haemoglobin in the bone marrow. Without enough iron, marrow makes smaller, paler red cells (low MCV) that carry less oxygen.
What this means
Tiredness, breathlessness, hair loss and brittle nails. In pre-menopausal women heavy periods are the commonest cause.
Advice
Treat the cause, not just the symptom. Eat iron-rich foods with vitamin C. Avoid tea and coffee at meals. Persistent deficiency in adults always deserves investigation.
Tests in this chain