Haemoglobin (Hb)
Haemoglobin is the iron-containing protein inside red blood cells that carries oxygen from the lungs to every tissue in the body and returns carbon dioxide to be exhaled. It is the most clinically measured protein in medicine and a cornerstone of the Complete Blood Count (CBC).
Normal Range
Men: 13.5–17.5 g/dL; Women: 12.0–15.5 g/dL; Children: varies by age
Reference ranges may vary slightly between laboratories. Always interpret your result in context with your doctor.
Why is Haemoglobin measured?
Haemoglobin testing diagnoses and monitors anaemia — one of the most common conditions worldwide affecting 1.6 billion people. It also screens for blood disorders, iron deficiency, and helps assess surgical risk, response to treatment, and overall nutritional status.
High Haemoglobin means…
High haemoglobin (polycythaemia) thickens the blood and increases clotting risk. It can indicate chronic lung disease, living at high altitude, dehydration, certain kidney tumours, or polycythaemia vera (a bone marrow disorder).
Low Haemoglobin means…
Low haemoglobin means anaemia — insufficient oxygen-carrying capacity. The most common cause globally is iron deficiency. Anaemia causes fatigue, breathlessness, and impaired cognitive function. Severe anaemia (below 7 g/dL) may require transfusion.
Symptoms associated with abnormal Haemoglobin
When Haemoglobin is high:
- Headaches and dizziness
- Flushed skin
- Blurred vision
- Blood clots
When Haemoglobin is low:
- Fatigue, weakness, and low energy
- Shortness of breath on exertion
- Pale skin, gums, or nail beds
- Cold hands and feet
- Dizziness or lightheadedness
- Rapid or irregular heartbeat
How to improve your Haemoglobin
- For iron-deficiency anaemia, eat iron-rich foods: red meat, spinach, lentils, fortified cereals.
- Pair iron-rich foods with vitamin C (citrus, tomatoes) — vitamin C doubles iron absorption.
- Avoid tea or coffee with iron-rich meals — tannins bind iron and reduce absorption by up to 60%.
- If prescribed iron supplements, take on an empty stomach for best absorption, or with a small amount of food if it causes stomach upset.
Frequently asked questions about Haemoglobin
What is a dangerously low haemoglobin level?
Haemoglobin below 8 g/dL is considered severely low and usually requires medical intervention. Below 7 g/dL may require a blood transfusion, depending on symptoms. Most people can function with haemoglobin as low as 10 g/dL, though with reduced exercise tolerance.
Can low haemoglobin cause hair loss?
Yes. Iron-deficiency anaemia — the most common cause of low haemoglobin — frequently causes diffuse hair shedding (telogen effluvium). The hair follicles are sensitive to iron availability. Hair typically regrows within 6–12 months after iron stores are replenished.
Medical Sources
This page is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider about your individual results.