Haemoglobin (Hb)

What is haemoglobin?

Haemoglobin (Hb) is an iron-containing protein packed inside every red blood cell. Its job is to pick up oxygen in the lungs, transport it through the bloodstream, and release it to tissues and organs throughout the body. Without adequate haemoglobin, your cells are starved of the oxygen they need to function.

A haemoglobin measurement is the central component of a Full Blood Count (FBC) — one of the most frequently requested blood tests in clinical medicine. It gives a direct indication of whether your blood is carrying enough oxygen, making it essential for diagnosing anaemia, monitoring treatment, and identifying rarer conditions such as polycythaemia.

Haemoglobin levels naturally differ between men and women due to hormonal influences on red cell production. Women of childbearing age typically have lower levels, partly due to menstrual blood loss. Levels also change in pregnancy, at altitude, and with increasing age.

Normal reference range

• Adult males: 130–170 g/L
• Adult females: 120–150 g/L

Important: Reference ranges vary between laboratories and depend on individual factors including age, sex, pregnancy status, and medication. Always interpret your result in the context of a clinician review. The Vesey reviews every result before release.

What a high haemoglobin may indicate

A result above the upper reference limit warrants investigation. Possible causes include:

• Polycythaemia vera — a bone marrow disorder causing overproduction of red blood cells
• Chronic obstructive pulmonary disease (COPD) — the body compensates for low oxygen by making more red cells
• Living at high altitude — a normal physiological adaptation to reduced atmospheric oxygen
• Dehydration — reduced plasma volume artificially concentrates haemoglobin
• Heavy smoking — carbon monoxide from cigarettes displaces oxygen, stimulating red cell production
• Sleep apnoea — repeated nocturnal oxygen dips trigger compensatory erythropoiesis
• Erythropoietin-producing tumours — rare but important to exclude

What a low haemoglobin may indicate

Low haemoglobin defines anaemia. The severity — mild (just below range), moderate, or severe — guides urgency of treatment. Common causes include:

• Iron deficiency anaemia — the most common worldwide cause, often from poor diet, heavy periods, or gastrointestinal blood loss
• Vitamin B12 or folate deficiency — leads to large, poorly-functioning red cells (megaloblastic anaemia)
• Anaemia of chronic disease — seen in inflammatory conditions, cancer, kidney disease, and chronic infection
• Chronic kidney disease — the kidneys produce erythropoietin to stimulate red cell production; failing kidneys produce less
• Haemolytic anaemia — red cells are destroyed faster than they can be replaced
• Bone marrow failure or infiltration — reduced red cell production from the marrow itself
• Haemoglobinopathies — inherited disorders such as sickle cell disease or thalassaemia

Symptoms of anaemia typically appear when haemoglobin falls below 100 g/L and include fatigue, breathlessness on exertion, pallor, dizziness, and palpitations.

Get tested at The Vesey, Sutton Coldfield

Haemoglobin is measured as part of the Full Blood Count (FBC). At The Vesey Private Hospital, the following panels include this marker:

• Full Blood Count — £144 (includes Hb, white cell differential, platelets)
• Anaemia Profile — comprehensive iron, B12, folate, and FBC screen
• Lifestyle Screen — wide-ranging health check including FBC
• Advanced Health Screens — full biomarker profiling including haematology

Results are reviewed by a clinician before release. Same-day and next-day appointments available Monday–Saturday in Sutton Coldfield town centre.

Frequently asked questions

What is a normal haemoglobin level?

Normal haemoglobin is 130–170 g/L for adult males and 120–150 g/L for adult females. Values vary by laboratory and are influenced by age, altitude, and pregnancy status. Always interpret results alongside a clinical review.

What does low haemoglobin mean?

Low haemoglobin (anaemia) means your red blood cells are carrying less oxygen than needed. Common causes include iron deficiency, vitamin B12 or folate deficiency, chronic disease, and blood loss. Symptoms typically include tiredness, breathlessness, and pallor.

What does high haemoglobin mean?

High haemoglobin can indicate polycythaemia vera, chronic lung disease (COPD), living at high altitude, dehydration, or smoking. It requires clinical investigation to identify the underlying cause.

Is haemoglobin the same as iron?

No. Haemoglobin is the protein that contains iron and carries oxygen. Your haemoglobin level reflects how well your red cells are functioning overall. Ferritin and serum iron are separate tests that directly measure your iron stores and supply.

Do I need to fast before a haemoglobin blood test?

Fasting is not required for a haemoglobin test alone. However, if your haemoglobin is being measured as part of a broader panel that includes HbA1c, cholesterol, or glucose, a 9–12 hour overnight fast may be recommended. Our team will advise you at the time of booking.