Haemoglobin

An abnormal hemoglobin may point to:

• Low hemoglobin (anaemia): iron deficiency, vitamin B12 or folate deficiency, chronic blood loss, thalassaemia or sickle cell disease, chronic kidney disease, long-standing infection or inflammation, hookworm infection, and bone marrow problems.
• High hemoglobin: dehydration, smoking, chronic lung disease, living at altitude, sleep apnoea, certain medicines such as testosterone, and polycythaemia vera, a rare bone marrow condition.

The cause is found with follow-up tests such as MCV and other red cell indices, serum ferritin, iron studies, vitamin B12 and folate levels, and, where appropriate, a peripheral blood smear or hemoglobin electrophoresis.