A high hemoglobin (Hb or Hgb) count is a blood test result. It means that the level of a key protein in red blood cells called hemoglobin is higher than is typical. Hemoglobin carries oxygen throughout the body. It also gives red blood cells their color.

Hemoglobin is measured in grams per deciliter (g/dL) of blood. What's considered a high hemoglobin count differs slightly from one lab to another. In general, a high hemoglobin count is more than 16.6 g/dL for men and more than 15 g/dL for women. In children, a high hemoglobin count varies with age and sex.

Other factors that can affect hemoglobin count include:

• The time of day.
• How hydrated you are.
• How high above sea level you are.