Hemoglobin is a protein in red blood cells that transports oxygen throughout the body. A hemoglobin test is used to determine how much hemoglobin is in the blood.
The hemoglobin test may be performed as part of a routine health exam or during a time of illness, but it's often done as part of a complete blood count (CBC). The hemoglobin test is primarily used to detect various types of anemia, a common condition that occurs when the amount of healthy red blood cells a person's blood is too low.
No special preparation is necessary. However, if your child has had a transfusion in the last 3 months, or if he or she smoked just prior to the test, hemoglobin levels may be altered, so let the doctor know.
On the day of the test, it may help to have your child wear a short-sleeve shirt to allow easier access for the technician who will be drawing the blood.
A health professional will usually draw the blood from a vein. For an infant, the blood may be obtained by puncturing the heel with a small needle (lancet). If the blood is being drawn from a vein, the skin surface is cleaned with antiseptic, and an elastic band (tourniquet) is placed around the upper arm to apply pressure and cause the veins to swell with blood. A needle is inserted into a vein (usually in the arm inside of the elbow or on the back of the hand) and blood is withdrawn and collected in a vial or syringe.
After the procedure, the elastic band is removed. Once the blood has been collected, the needle is removed and the area is covered with cotton or a bandage to stop the bleeding. Collecting blood for this test will only take a few minutes.
Either method (heel or vein withdrawal) of collecting a sample of blood is only temporarily uncomfortable and can feel like a quick pinprick. Afterward, there may be some mild bruising, which should go away in a few days.
Hemoglobin samples are usually analyzed in a lab with a machine that measures the intensity of hemoglobin's red color to determine how much of it is present in the blood. Hemoglobin test results are usually available after a few hours or the next day.
The hemoglobin test is considered a safe procedure. However, as with many medical tests, some problems can occur with having blood drawn:
Having a blood test is relatively painless. Still, many children are afraid of needles. Explaining the test in terms your child might understand can help ease some of the fear.
Allow your child to ask the technician any questions he or she might have. Tell your child to try to relax and stay still during the procedure, as tensing muscles and moving can make it harder and more painful to draw blood. It also may help if your child looks away when the needle is being inserted into the skin.
If you have questions about the hemoglobin test, speak with your doctor.
Reviewed by: Steven Dowshen, MD
Date reviewed: February 2011
|American Medical Association (AMA) The AMA has made a commitment to medicine by making doctors more accessible to their patients. Contact the AMA at: American Medical Association|
515 N. State St.
Chicago, IL 60610
|American Academy of Pediatrics (AAP) The AAP is committed to the health and well-being of infants, adolescents, and young adults. The website offers news articles and tips on health for families.|
|American Society of Hematology This group provides information relating to blood, blood-forming tissues, and blood diseases.|
|Word! Complete Blood Count (CBC) Blood is made up of different parts, such as red blood cells, white blood cells, and platelets.|
|Iron-Deficiency Anemia A lack of iron in the blood can lead to iron-deficiency anemia, the most common nutritional deficiency in the world. Find out more about this disorder and how it can be treated.|
|Blood Test: Complete Blood Count The complete blood count (CBC) is the most common blood test. It analyzes red blood cells, white blood cells, and platelets.|
|Blood Test (Video) This video shows what it's like to get a blood test.|
|Getting a Blood Test (Video) A blood test might sound scary, but it usually takes less than a minute. Watch what happens in this video for kids.|
|Anemia Anemia is common in teens because they undergo rapid growth spurts, when the body has a greater need for nutrients like iron. Learn about anemia, including how to lower your risk of getting it and how it's treated.|
|About Anemia What does it mean when a kid has anemia? Learn about anemia, why kids get it, and how it's treated in our article for kids.|
|Anemia Anemia, one of the more common blood disorders, occurs when the number of healthy red blood cells decreases. This can result in a variety of symptoms, including fatigue and stress on all the body's organs.|
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