I. What Is Insulin-Like Growth Factor-1 (IGF-1) Testing?

IGF-1 testing can help determine your levels of human growth hormone and how well your pituitary gland is working. The test can also be used to diagnose conditions where excess growth hormones cause large stature (gigantism) in children or enlarged bones (acromegaly) in adults, but these are rare conditions.

Why you should get tested

IGF-1 testing can help doctors detect conditions related to deficiency or overproduction of growth hormones. A treatment plan can be developed as soon as a diagnosis is confirmed.

Who should get tested

Anyone showing symptoms of having too much or too little human growth hormone, or possible problems with the pituitary gland, should be tested. This includes:

  • Children with delayed growth or large stature
  • Adults with enlarged hands, feet, and facial bones
  • Adults with weak muscles and decreased bone density

When to get tested

Your doctor may order an IGF-1 test if there are concerns about your pituitary gland function and levels of growth hormones, based on your symptoms and medical history. The test may also be used to monitor growth hormone treatments.

II. How to Prepare for IGF-1 Testing

Usually, there’s no preparation needed for an IGF-1 blood test. But in some cases, you may be asked to fast depending on why the test is ordered. Your doctor will advise if this is required.

You should advise your health care provider of medications and supplements you’re taking. Vitamin B7, or biotin, can affect your test results if taken in high doses.

III. How an IGF-1 Test Works

IGF-1 tests are performed on a blood sample. If the test is required, your doctor gives you an order to take it to a lab. A technician collects a small amount of blood from your hand or arm using a small needle and vial, then sends the sample for analysis. The blood draw usually takes a few minutes.

You can buy an IGF-1 test kit on some websites. The kits come with the supplies needed to collect a blood sample in the privacy of your home by pricking your fingertip and placing a drop of blood on a card. The blood sample is returned to the lab by mail for analysis.

IV. Understanding IGF-1 Testing Results

IGF-1 test results are usually sent to your doctor or are available online within a week, although this can vary by lab. The results are given as a measurement of IGF-1 in nanograms per milliliter (ng/mL).

Normal ranges depend on age and gender, as levels of IGF-1 increase throughout childhood and decline after puberty. Your physician should interpret the results as there are other reasons for abnormal levels of IGF-1. For example, anorexia or malnutrition can cause low IGF-1 levels.

Measurements of IGF-1 outside a normal range can indicate:

  • Hypopituitarism or a pituitary tumor
  • Hypothyroidism
  • Insensitivity to growth hormones
  • Acromegaly
  • Gigantism

Based on your results and medical history, your doctor may order additional tests or confirm a diagnosis and recommend treatment.

V. Learn From Our IGF-1 Sources

Consult the sources we used to learn more about IGF-1 testing and related conditions.