Hemoglobin is the iron-containing metalloprotein, which assists in the transport of oxygen in blood through Red Blood Cells (RBCs). Hemoglobin transports oxygen from lungs to the rest of the body. The mutation of genes in the hemoglobin protein can cause several hereditary diseases, such as sickle-cell anemia and thalassemia.

  Hemoglobin test is used to measure the amount of hemoglobin. It indicates how well our blood can carry oxygen throughout the body. It also helps in determining the severity of anemia in which body contains very few RBCs or polycythemia in which, the body has a large number of RBCs. The test helps in monitoring the treatment of anemia and polycythemia. It also enables the doctor to decide whether the body requires blood transfusion during the treatment of anemia. Hemoglobin test can also be a part of Complete Blood Count (CBC). Patients suffering from continuous bleeding problems are also recommended to get their hemoglobin tested.

  The blood of an adult should normally contain 12 to 18 grams of hemoglobin per deciliter. The hemoglobin level can elevate above normal due to dehydration, excess manufacturing of RBCs in the bone marrow, and severe lung disease. The low hemoglobin level causes anemia, which may be due to the deficiency of iron and other essential vitamins, such as B6, B12, and folate. It can also be a genetic defect as in sickle-cell anemia or may be caused by liver cirrhosis, kidney diseases, and excessive bleedings to name a few.

  Hemoglobin test should also be done during pregnancy to check if the count is normal or has decreased. Study shows that hemoglobin level rises around eight in the morning and decreases around 8 in the evening. People who smoke heavily and those who stay on high altitudes have higher count of RBCs.