Haemoglobin (Hb)

Haemoglobin carries oxygen inside red blood cells. Low values define anaemia — a finding, not a diagnosis: iron deficiency, blood loss, chronic disease and vitamin deficiencies all lower it in different patterns.

Mildly low results are usually re-checked together with iron studies before any conclusion. A value that keeps falling, or symptoms such as breathlessness and unusual fatigue, deserve a proper work-up rather than supplements bought on a guess.