What should you know about hemoglobin blood test?

Haemoglobin carries oxygen through the bloodstream. A lower result may fit Anaemia, blood loss, low iron, long-term inflammation or kidney disease, but the number needs to be read with the rest of the full blood count and your symptoms. A higher result can relate to dehydration, smoking, living at altitude or other conditions. One result does not identify the cause by itself. Your clinician may consider red-cell size, iron stores, kidney function, bleeding and diet.

Most haemoglobin tests use a small blood sample from a vein. Ask whether you should fast; preparation depends on the other tests ordered. Tell the clinician about supplements, medicines, heavy periods, recent illness and dietary restrictions. Do not begin iron supplements solely from a result without advice. Depending on the pattern, follow-up may explore Coeliac Disease, Crohn's Disease, Chronic Kidney Disease or another cause of altered blood counts.

Seek urgent medical help for breathlessness at rest, chest pain, fainting, new confusion, heavy ongoing bleeding, black stools or severe weakness. Arrange prompt review for worsening tiredness, paleness, fast heartbeat or breathlessness with ordinary activity. A result that is outside the laboratory range is not automatically an emergency, but it should be interpreted with your history and the laboratory’s own reference interval.

What does my haemoglobin result mean alongside the other blood-count values? Is iron deficiency or blood loss possible? Do I need repeat testing or additional tests? Could a medicine, diet or health condition be affecting it?