Insulin-like growth factor binding protein 3 (IGFBP-3) is the main carrier of somatomedin C (also called insulin-like growth factor-1, or IGF-1) in the body. Blood levels of both these proteins are controlled by human growth hormone (hGH), a hormone that's produced by the pituitary gland, a pea-sized gland in the brain that works with the endocrine system. The pituitary gland regulates growth and the function of other glands.
But IGFBP-3 is more than just a transporter. It also helps extend the life of somatomedin C in the blood and helps control its effects on body tissues.
Levels of IGFBP-3 are highest during childhood and puberty, then they decrease during adulthood. Levels also may be affected by sexual maturation and nutritional status.
The main reason doctors order the IGFBP-3 test is for its usefulness as an indicator of whether someone is producing a normal amount of human growth hormone. In this way, the IGFBP-3 test is used to check for pituitary gland disorders and abnormalities in growth hormone production.
Symptoms such as short stature or excessive growth (gigantism) may warrant an IGFBP-3 test. The test also might be used to monitor treatment of growth disorders.
On the day of the test, having your child wear a T-shirt or short-sleeved shirt can make things easier for your child and the technician who will be drawing the blood.
A health professional will usually draw the blood from a vein, after cleaning the skin surface with antiseptic, and then placing an elastic band (tourniquet) 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 A needle is inserted into a vein (usually in the arm inside of the elbow or on the back of the hand) and blood is withdrawn and collected in a vial or syringe.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.
Collecting a sample of blood for the test 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.
The blood sample will be processed by a machine, and the results are commonly available after a few days.
The IGFBP-3 test is considered a safe procedure. However, as with many medical tests, some problems can occur with having blood drawn, such as:
Having a blood test is relatively painless. Still, many children are afraid of needles. Explaining the test in terms your child can understand might 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 for your child to look away when the needle is being inserted into the skin.
If you have questions about the IGFBP-3 test, speak with your doctor.
Reviewed by: Yamini Durani, MD
Date reviewed: July 2014
|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.|
|Human Growth Foundation The Human Growth Foundation is a resource for kids and teens with growth problems.|
|Lab Tests Online This non-commercial site was developed by laboratory professionals to educate caregivers, patients, and patients' families about lab tests.|
|Blood Test (Video) These videos show what's involved in getting a blood test and what it's like to be the person taking the blood sample.|
|Blood Test: Somatomedin C (IGF-1) A somatomedin C test usually is ordered to check for pituitary gland disorder and abnormalities in growth hormones production.|
|Endocrine System Although we rarely think about them, the glands of the endocrine system and the hormones they release influence almost every cell, organ, and function of our bodies.|
|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.|
|Growth Disorders Everyone grows and matures differently. Usually, this is totally normal. A growth disorder, however, means that a kid has abnormal growth - for example, growing a lot slower or a lot faster than other kids the same age.|
|What Is a Growth Disorder? The other kids in the class have been getting taller and developing into young adults, but your child's growth seems to be lagging behind. Could a growth disorder be the cause?|
|Growth Problems In most cases, teens who are small are just physically maturing a bit more slowly than their friends. Occasionally, though, there's a medical reason why some kids and teens stop growing. Find out about growth problems and how doctors can help.|
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