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Medical glossary

Haemoglobin

Haemoglobin is the protein in red blood cells that carries oxygen from the lungs to the tissues.

Last updated: ~1 min read
A ribbon model of the haemoglobin protein, made of four chains
Figure 1.Haemoglobin — the protein that carries oxygen

01Short answer

Haemoglobin is measured in the complete blood count and is the main marker of anaemia. Normal ranges differ by age, sex and laboratory. During leukaemia treatment haemoglobin often falls; your doctor decides on a transfusion based on both the number and your symptoms. Haemoglobin is not the same as your iron level.

02Simple explanation

Carries oxygen.

Part of the blood count.

Normal ranges differ.

Transfusion is the doctor's decision.

03Scientific explanation

NCI: haemoglobin is the protein in red blood cells that carries oxygen.

The NCI Dictionary explains cancer terms in plain language; check the exact meaning for your situation with your doctor.

04What happens in the body?

When it is low

Tiredness, breathlessness and paleness.

The protein
Figure 2.The protein — Haemoglobin

How to read it

Check the laboratory's reference range.

The lungs
Figure 3.The lungs — Haemoglobin

Where you will see this word

In test results, discharge letters and conversations with your doctor. Write the word down and ask what it means.

Ask your doctor

The general meaning and the meaning of your own result can differ. The most important question is “What does this mean for me?”

05From an unfamiliar word to a clear answer: four steps

Write it down, look it up, prepare a question, ask.

Write it down — From a result or a conversation.1Write it downFrom a result or a conversation.
Look it up — Learn the plain meaning.2Look it upLearn the plain meaning.
Prepare a question — What does this mean for me?3Prepare a questionWhat does this mean for me?
Ask — Your doctor gives the personal explanation.4AskYour doctor gives the personal explanation.
UnderstandingResults feel less frightening.
ConversationA shared language with your doctor.
SafetyNot drawing conclusions alone.

06Key points at a glance

TopicIn brief
When it is lowTiredness, breathlessness and paleness.
How to read itCheck the laboratory's reference range.
Where you will see this wordIn test results, discharge letters and conversations with your doctor. Write the word down and ask what it means.
Ask your doctorThe general meaning and the meaning of your own result can differ. The most important question is “What does this mean for me?”

07Key terms

Hb
Short for haemoglobin.
Haematocrit
The share of red cells in the blood.
Term
A word with a precise medical meaning.
Reference range
The range a laboratory considers normal.

08Key points

  • Learn.
  • Ask your doctor.
  • Write it down.
  • Write the word down.
  • Ask what it means.

09Frequently asked questions

Can I raise haemoglobin with food?

In leukaemia the cause is different; talk to your doctor.

When is a transfusion needed?

Your doctor decides from the numbers and symptoms.

This word is in my results: should I worry?

The word itself does not mean a serious or mild condition; get the explanation from your doctor.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Can I raise haemoglobin with food?

  2. When is a transfusion needed?

  3. This word is in my results: should I worry?

My questions

12Sources

  1. National Cancer Institute. NCI Dictionary of Cancer Terms: hemoglobin
  2. MedlinePlus. Complete Blood Count (CBC)
  3. National Cancer Institute. NCI Dictionary of Cancer Terms
  4. National Cancer Institute. Leukemia
  5. National Cancer Institute (NCI). NCI Dictionary of Cancer Terms: blast
  6. National Cancer Institute. NCI Dictionary of Cancer Terms: absolute neutrophil count
  7. National Cancer Institute (NCI). NCI Dictionary of Cancer Terms: Philadelphia chromosome
  8. American Cancer Society. Neutropenia (Low White Blood Cell Counts)
  9. National Cancer Institute. NCI Dictionary of Cancer Terms: bone marrow aspiration
  10. National Cancer Institute. NCI Dictionary of Cancer Terms: polymerase chain reaction
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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