High Hemoglobin Count


What is high hemoglobin count?

High hemoglobin (Hgb) count occurs when your red blood cells have an unusually high amount of the blood protein hemoglobin. Hemoglobin gives red blood cells their red color. It helps carry oxygen from your lungs to the rest of your body and carries carbon dioxide (CO2) from the rest of your body back to your lungs. Another name for high hemoglobin is polycythemia.

What is the difference between high hemoglobin and hematocrit?

Hematocrit is the volume of red blood cells compared to other blood cells. People with high hemoglobin often also have high hematocrit, meaning they have irregularly high red blood cell counts.

What are high hemoglobin levels?

Both your biological sex and age affect your hemoglobin levels. Typically, hemoglobin levels are considered high if they’re:

  • Above 16.5 grams per deciliter (g/dL) in an adult who was assigned male at birth.
  • Above 16 g/dL in an adult who was assigned female at birth.
  • Above 16.6 g/dL in a child.
  • Above 18 g/dL in an infant.

Environmental factors such as altitude, time of day and how hydrated you are also can affect your hemoglobin levels.

How do I know if I have high hemoglobin?

A blood test is the only way to know if you have high hemoglobin. Some of the side effects of high hemoglobin may include:

Is high hemoglobin serious?

You should take high hemoglobin levels seriously. Sometimes, high hemoglobin points to a serious underlying condition. Even if you don’t have an underlying condition, it’s important to treat a high hemoglobin count. Irregularly high hemoglobin levels can lead to complications such as blood clots.

Possible Causes

What are the most common causes of high hemoglobin count?

You may have high hemoglobin because of a medical condition, such as:

Other factors that can lead to high hemoglobin count include:

Care and Treatment

How is high hemoglobin count treated?

Treatment for high hemoglobin count varies depending on the underlying cause. In some cases, your healthcare provider may recommend a phlebotomy. In a phlebotomy, a healthcare provider inserts a needle into one of your veins and removes extra red blood cells. You may need to have multiple phlebotomies until your hemoglobin levels are within a typical range.

What should I do if my hemoglobin is high?

See your healthcare provider if you have high hemoglobin or think you may. They can use a hemoglobin blood test to check your hemoglobin levels and offer treatment options.

How can I prevent high hemoglobin count?

You can’t always prevent high hemoglobin. But you can lower your risk of developing high hemoglobin with a few lifestyle changes:

  • Avoid using performance-enhancing drugs.
  • Eat a nutritious diet with plenty of fruits and vegetables.
  • Stay hydrated by drinking plenty of water and other liquids.
  • Quit smoking.

When to Call the Doctor

When should a doctor treat high hemoglobin count?

Your doctor should always treat high hemoglobin count. Call your healthcare provider if you experience new symptoms of high hemoglobin. If you know you have high hemoglobin, call your healthcare provider if you experience worsening symptoms.

A note from Cleveland Clinic

High hemoglobin count occurs when you have unusually high levels of a specific blood protein. The blood protein hemoglobin helps carry oxygen throughout your body and takes carbon dioxide to your lungs. High hemoglobin levels can lead to dizziness, fatigue, easy bruising and other symptoms. Depending on the underlying cause of high hemoglobin, your healthcare provider may recommend treatment to remove excess red blood cells from your blood.

Last reviewed by a Cleveland Clinic medical professional on 06/20/2022.


  • Billett HH. Hemoglobin and Hematocrit. In: Walker HK, Hall WD, Hurst JW, eds. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Accessed 6/20/2022.
  • National Institutes of Health, National Library of Medicine. Hemoglobin Test. (https://medlineplus.gov/lab-tests/hemoglobin-test/) Accessed 6/20/2022.

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