The normal level of hemoglobin for an adult woman is 12.1 to 15.1 g/dL, according to MedlinePlus. The normal range for men is 13.8 to 17.2. The test measures how much of the oxygen-carrying protein hemoglobin is in the red blood cells of the blood.
Hemoglobin tests are commonly done as part of a complete blood count. MedlinePlus says the test is often ordered before or after surgery, when signs of bleeding are present, or for symptoms such as fatigue or unexplained weight loss. The test is also used to monitor anemia, cancer patients undergoing treatment and persons on medications that may cause low blood counts.