In a blood test, "HB" is an abbreviation for hemoglobin. The value describes the hemoglobin levels in the blood.
Hemoglobin is a very important part of the blood. This protein is found in red blood cells and is responsible for carrying oxygen through the body. Hemoglobin tests are usually included with blood tests.
Normal hemoglobin levels vary depending on age and gender. Normal levels for men range between 13.8 to 17.2 grams of hemoglobin per deciliter of blood. Normal levels for women range between 12.1 to 15.1 grams per deciliter of blood. Results for children vary even more. Newborn babies have a normal range of anywhere between 14 and 24 grams per deciliter, whereas older babies have much lower levels, at 9.5 to 13 grams per deciliter.
Lower than average hemoglobin levels can indicate a variety of conditions. Anemia, low blood iron, low B vitamin levels and malnutrition are common causes. Women may have low hemoglobin levels if they have heavier periods. Low hemoglobin levels can also be symptoms of serious conditions such as leukemia, bleeding in the digestive tract, bone marrow disorders, kidney disease or rheumatoid arthritis.
Higher than average hemoglobin levels can also be indicators for serious conditions. These include bone marrow disorders, lung disorders and heart defects. These conditions cause low blood oxygen levels, which increases the hemoglobin count.