Hemoglobin blood test
In short
A typical adult hemoglobin result is 11.6 to 15 g/dL for women and 13.2 to 16.6 g/dL for men. A slightly high level most often comes from dehydration, smoking or living at high altitude. A level that stays high on repeat tests is worth looking into. Always read your result against the range printed on your own report.
The protein in red blood cells that carries oxygen.
Hemoglobin is the iron-rich protein inside red blood cells that picks up oxygen in the lungs. It is the main number doctors use to check for anemia, which means too little hemoglobin. Women usually run a little lower than men.
Is my Hemoglobin high or low?
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Typical range
| For | Range | Unit |
|---|---|---|
| Female | 11.6–15 | g/dL |
| Male | 13.2–16.6 | g/dL |
Typical ranges for adults. Labs differ a little, so the range printed next to your result is the one to go by.
If your Hemoglobin is high
A slightly high level most often comes from dehydration, smoking or living at high altitude. A level that stays high on repeat tests is worth looking into.
Common reasons
- Not drinking enough before the test (dehydration)
- Smoking, which raises hemoglobin to make up for lost oxygen
- Living at high altitude
- Sleep apnea (breathing pauses in sleep) or a long-term lung condition
- Some hormone treatments, especially male hormone therapy
- Less often: polycythemia vera, a bone marrow condition making too many red cells
If your Hemoglobin is low
A low level is called anemia. Mild anemia is common, and red cell size and iron tests usually point to the reason.
Common reasons
- Low iron, often from heavy periods or pregnancy
- Pregnancy, when extra fluid naturally thins the blood
- Low vitamin B12 or folate
- Long-term kidney disease or ongoing inflammation
- Recent bleeding, surgery or blood donation
- Less often: slow, hidden bleeding from the stomach or bowel
- Less often: red cells breaking down early, or a bone marrow problem
What can throw it off
Dehydration, pregnancy, smoking, recent blood loss and living at high altitude can all shift hemoglobin.
When it can’t wait
A Hemoglobin of 20 g/dL or more, or 6 g/dL or less, usually needs a doctor's attention the same day. Call your doctor’s office, or their after-hours line. If you feel very unwell, call your local emergency number.
Questions to take to your appointment
- 1Has this changed since my last test?
- 2Should my iron, vitamin B12 and folate be checked?
- 3Do I need more tests to find the cause?
Read together with
Doctors rarely read Hemoglobin alone. These usually sit next to it.
- HematocritHow much of the blood's volume is red blood cells.
- RBCThe number of red blood cells, which carry oxygen around the body.
- MCVThe average size of your red blood cells.
- FerritinThe body's iron-storage protein; its level mirrors your iron reserves.
- Reticulocyte countYoung red blood cells, showing how fast new ones are made.
Quick answers
What is the hemoglobin blood test?
Hemoglobin: The protein in red blood cells that carries oxygen. Hemoglobin is the iron-rich protein inside red blood cells that picks up oxygen in the lungs. It is the main number doctors use to check for anemia, which means too little hemoglobin. Women usually run a little lower than men.
What is a normal hemoglobin level?
For most adults, hemoglobin is typically 11.6 to 15 g/dL for women and 13.2 to 16.6 g/dL for men. Labs differ a little, so the range printed next to your result is the one to go by.
What does a high hemoglobin mean?
A slightly high level most often comes from dehydration, smoking or living at high altitude. A level that stays high on repeat tests is worth looking into. Common reasons include not drinking enough before the test (dehydration); smoking, which raises hemoglobin to make up for lost oxygen; living at high altitude; and sleep apnea (breathing pauses in sleep) or a long-term lung condition. A doctor reads it together with your other results and how you feel.
What does a low hemoglobin mean?
A low level is called anemia. Mild anemia is common, and red cell size and iron tests usually point to the reason. Common reasons include low iron, often from heavy periods or pregnancy; pregnancy, when extra fluid naturally thins the blood; low vitamin B12 or folate; and long-term kidney disease or ongoing inflammation.
What can affect my hemoglobin result?
Dehydration, pregnancy, smoking, recent blood loss and living at high altitude can all shift hemoglobin.
When is my hemoglobin result urgent?
A hemoglobin result of 20 g/dL or more, or 6 g/dL or less usually needs a doctor's attention the same day. Call your doctor's office or their after-hours line. If you feel very unwell, call your local emergency number.
What should I ask my doctor about my hemoglobin?
Questions worth taking to the appointment: Has this changed since my last test? Should my iron, vitamin B12 and folate be checked? Do I need more tests to find the cause?
What this page can’t do
It reads each number on its own.
Doctors read results together — ALT with AST, ferritin with hemoglobin, TSH with free T4. A pattern says more than any single flag.
It doesn't know you.
Your age, your medicines, how you feel and your last result all change what a number means.
It doesn't remember.
Close this page and your results are gone. That's on purpose: nothing was ever sent to us.
We also make Vita: Health Coach, an app for those parts. It reads your whole report with your medicines and history in mind, answers follow-up questions in plain words, and keeps your reports in one place — for you and for the people you look after.
Vita: Health Coach on the App StoreSources
- Mayo Clinic Laboratories — CBC with differential, reference values
- Mayo Clinic Laboratories — Critical values list
- MedlinePlus — Complete blood count (CBC)
Stuck on a word? See the medical words. How we choose our sources. More about Vita Health Coach.