High hemoglobin count
Medically reviewed on January 11, 2018
A high hemoglobin count indicates an above-normal level of hemoglobin in your blood. Hemoglobin (often abbreviated as Hb or Hgb) is the oxygen-carrying component of red blood cells.
A high hemoglobin count is somewhat different from a high red blood cell count, because each cell may not have the same amount of hemoglobin proteins. Therefore, you could have a high hemoglobin count even if your red blood cell count falls within the normal range.
The threshold for a high hemoglobin count is slightly different from one medical practice to another. It's generally defined as more than 17.5 grams (g) of hemoglobin per deciliter (dL) of blood for men and 15.5 g/dL for women. In children, the definition of a high hemoglobin count varies with age and sex. Hemoglobin count may also vary due to time of day and how well-hydrated you are.
High hemoglobin count occurs most commonly when your body requires an increased oxygen-carrying capacity, usually because:
- You smoke
- You live at higher altitudes and your red blood cell production naturally increases to compensate for the lower oxygen supply there
High hemoglobin count occurs less commonly because:
- Your red blood cell production increases to compensate for chronically low blood oxygen levels due to poor heart or lung function.
- You have a bone marrow dysfunction that results in increased production of red blood cells.
- You've taken drugs or hormones, most commonly erythropoietin (EPO), that stimulate red blood cell production. You're not likely to get a high hemoglobin count from EPO given to you if you have chronic kidney disease. But EPO doping — getting injections to enhance athletic performance — can cause a high hemoglobin count.
A high hemoglobin count in the absence of any other abnormalities is unlikely to be related to any condition of concern. Specific disorders or other factors that may cause a high hemoglobin count include:
- COPD (chronic obstructive pulmonary disease)
- Heart failure
- Kidney cancer
- Liver cancer
- Living at a high altitude, where there's less oxygen in the air
- Other types of heart disease
- Other types of lung disease
- Polycythemia vera
- Smoking, which may result in low blood oxygen levels
When to see a doctor
A high hemoglobin count is rarely an unexpected finding or simply discovered by chance. It's usually found when your doctor has ordered tests to help diagnose a condition you're already experiencing. Talk to your doctor about what these results mean. A high hemoglobin count and results from other tests may already indicate the cause of your illness, or your doctor may suggest other tests to check your condition.