High hemoglobin count happens when you have unusually high levels of a blood protein called hemoglobin. Hemoglobin helps carry oxygen throughout your body and carries carbon dioxide to your lungs. Irregularly high hemoglobin levels can increase your risk of complications such as blood clots.
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.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
Both your biological sex and age affect your hemoglobin levels. Typically, hemoglobin levels are considered high if they’re:
Environmental factors such as altitude, time of day and how hydrated you are also can affect your hemoglobin levels.
A blood test is the only way to know if you have high hemoglobin. Some of the side effects of high hemoglobin may include:
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.
You may have high hemoglobin because of a medical condition, such as:
Other factors that can lead to high hemoglobin count include:
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.
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.
You can’t always prevent high hemoglobin. But you can lower your risk of developing high hemoglobin with a few lifestyle changes:
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.
Learn more about our editorial process.