IGF Binding Protein-3 (IGFBP-3) Blood Test

What Is an IGFBP-3 Test and Why Is It Done?

An insulin-like growth factor binding protein 3 (IGFBP-3) test measures the level of a protein in the blood called IGFBP-3. The test helps show if the body is making a normal amount of growth hormone (GH). This is a substance the pituitary gland makes that helps kids grow and develop.

Doctors usually order the test to:

• check for pituitary gland disorders and problems in growth hormone production (like short stature or excessive growth, also called gigantism)
• monitor treatment of growth disorders

What Is IGF Binding Protein-3 (IGFBP-3)?

IGFBP-3 is the main carrier of another protein in the body: somatomedin C (also called insulin-like growth factor-1, or IGF-1). Blood levels of both these proteins are controlled by GH.

IGFBP-3 also helps extend the life of somatomedin C in the blood and helps control its effects on body tissues.

Top Things to Know

• The insulin-like growth factor binding protein 3 (IGFBP-3) blood test shows how much IGFBP-3 (a protein) is in the blood.
• The test can help look for problems with the pituitary gland and growth hormone, and checks on growth disorder treatment.
• Kids might need to stop taking certain medicines or not eat or drink before the blood test.
• Your doctor can explain what it means if IGFBP-3 levels are low or high.

How Can I Help My Child Prepare for a Blood Test?

To help kids get ready for a blood test, find out if they need to fast (not eat or drink) or should stop taking medicines before the test. Explain what to expect during the test. If your child is nervous about it, work together on ways to stay calm. Deep breathing or even imagining being in a place that makes your child feel safe and relaxed can help.

What Do IGFBP-3 Test Results Mean?

Your doctor will explain what the results of the test mean for your child. What’s “normal” can vary based on things like age and gender.

IGFBP-3 levels are highest during childhood and puberty. They decrease during adulthood.

Low IGFBP-3 Level

A low level of IGFBP-3 could be due to things like growth hormone deficiency (when the pituitary gland makes too little GH) or poor nutrition.

High IGFBP-3 Level

A high level of IGFBP-3 could be due to things like a pituitary gland problem, which can cause gigantism.

What Else Should I Know?

When kids have an IGFBP-3 test, they may also need other tests, like a somatomedin C (IGF-1) blood test.

If you have questions about the IGFBP-3 test or what the results mean, talk to your doctor.