Blood Test

Haemoglobin (Hb) Test

Name: Haemoglobin Test: Normal Range & Low | HealthReview
Creator: Suman Konda
Published: 2026-07-05

Haemoglobin is the protein in red blood cells that carries oxygen to every cell in your body. A low result means anaemia; a high result can indicate dehydration or a blood disorder.

Written and clinically reviewed by Suman Konda, PharmD, Clinical Pharmacist · Based on peer-reviewed sources · Editorial policy · Not medical advice

Last reviewed and updated: 01 August 2026 · How we check our content

What is haemoglobin?

Haemoglobin (Hb or Hgb) is the iron-containing protein inside red blood cells that binds to oxygen in the lungs and delivers it throughout the body. It also carries carbon dioxide back to the lungs. The haemoglobin test is part of a Complete Blood Count (CBC) and is the primary test for diagnosing anaemia.

Haemoglobin normal range

Group	Normal Range (g/dL)	Interpretation
Adult men	13.5 – 17.5	Normal
Adult women	12.0 – 15.5	Normal
Pregnant women	≥ 11.0	Acceptable in pregnancy
Children (6-12 yrs)	11.5 – 15.5	Normal
Severe anaemia	< 8.0 (any adult)	Urgent assessment

LOW Haemoglobin: Anaemia

Low haemoglobin is called anaemia. The most common cause worldwide is iron deficiency due to poor diet, blood loss (heavy periods, GI bleeding) or poor absorption. Other causes: vitamin B12 or folate deficiency (megaloblastic anaemia), chronic kidney disease, chronic inflammatory conditions, thalassaemia and haemolytic anaemia. Symptoms include fatigue, weakness, pale skin, shortness of breath, dizziness and rapid heartbeat.

HIGH Haemoglobin: Polycythaemia

High haemoglobin (polycythaemia or erythrocytosis) causes include dehydration, high-altitude living, smoking, chronic lung disease (COPD) and polycythaemia vera (a bone marrow condition). Very high Hb thickens the blood and raises clot, stroke and heart attack risk.

Grades of anaemia

Severity	Hb (g/dL)	Typical symptoms
Mild	10 – 12 (women) / 10 – 13.5 (men)	Few or none
Moderate	8 – 9.9	Fatigue, breathlessness on exertion
Severe	< 8	Breathlessness at rest, chest pain
Critical	< 6.5	Emergency: may need transfusion

Questions to ask your doctor

What type of anaemia do I have?
Do I need iron, B12 or folate supplements?
Should I have ferritin and iron studies?
Do I need a colonoscopy to check for GI bleeding?
When should I retest?

Frequently Asked Questions

What does a low haemoglobin level mean?

Low haemoglobin indicates anaemia, reducing the blood's oxygen-carrying capacity and causing fatigue, pallor, and breathlessness. Further tests identify the type and cause, most commonly iron deficiency.

What causes a high haemoglobin level?

High haemoglobin can result from dehydration, smoking, living at altitude, or certain lung and bone-marrow conditions. Repeat testing and context help determine the cause.

How is haemoglobin different from ferritin?

Haemoglobin measures the oxygen-carrying protein in red cells, while ferritin reflects iron stores: ferritin often falls before haemoglobin does, giving an earlier warning of iron deficiency.

References

The clinical information on this page is drawn from peer-reviewed sources indexed by the US National Library of Medicine. Links go to the source so you can read it yourself.

Anemia. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK499994