The hemoglobin test is a blood test that measures how much hemoglobin is your blood. Hemoglobin is a protein in red blood cells that carries oxygen.
How the Test is Performed
A blood sample is needed.
How to Prepare for the Test
No special preparation is necessary.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
The hemoglobin test is a commonly ordered blood test and is almost always done as part of a complete blood count (CBC). Common reasons or conditions for ordering the hemoglobin test include:
Symptoms such as fatigue, feelings of poor health, or unexplained weight loss
Signs of bleeding are present
Before and after major surgery
Presence of chronic kidney disease or many other chronic medical problems
Monitoring of anemia and its cause
Monitoring during treatment for cancer
Monitoring medicines that may cause anemia or low blood counts
Normal results for adults vary, but in general are:
Male: 13.8 to 17.2 grams per deciliter (g/dL)
Female: 12.1 to 15.1 g/dL
Normal results for children vary, but in general are:
Newborn: 14 to 24 g/dL
Infant: 9.5 to 13 g/dL
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
LOWER THAN NORMAL HEMOGLOBIN
Low hemoglobin level may be due to:
Anemia due to red blood cells being destroyed earlier than normal (hemolytic anemia)
A rare bone marrow disease that leads to an abnormal increase in the number of blood cells (polycythemia vera)
The body not having as much water and fluids as it should (dehydration)
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
Fainting or feeling light-headed
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)
Hutchison RE, McPherson RA, Schexneider KI. Basic examination of blood and bone marrow. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 30.
Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.