Insulin-Like Growth Factor I (IGF-I) Blood Test

The IGF-1 blood test measures the level of insulin-like growth factor 1 in the blood. IGF-1, also known as somatomedin C, is a hormone produced in the liver in response to growth hormone (GH) secretion from the pituitary gland. Checking IGF-1 is an important part of screening for growth disorders and GH deficiency.

What Does the IGF-1 Test Measure?

IGF-1 promotes tissue growth, cellular replication and regeneration throughout the body. About 70% of IGF-1 in the circulation is dependent on GH stimulation of its production. Low IGF-1 along with low GH indicates inadequate growth hormone.

There are two types of IGF-1 blood tests:

• Total IGF-1 – Measures both bound and unbound IGF-1 levels.
• Free IGF-1 – Specifically measures the active or unbound form of IGF-1.

Both total and free IGF-1 decline with age. IGF-1 levels are a useful tool for evaluating growth problems in children and GH deficiency in adults when used in combination with provocative GH stimulation testing.

Who Should Have IGF-1 Testing?

Checking IGF-1 levels is recommended for:

• Adults with suspected pituitary disease or hormone deficiencies
• Diagnosing causes of abnormal growth – too fast or too slow
• Monitoring IGF-1 treatment for growth disorders
• Assessing effectiveness of GH replacement therapy

Measuring IGF-1 helps determine if poor growth or GH deficiency is due to inadequate IGF-1 response or GH resistance.

Preparing for the IGF-1 Blood Test

No special preparation is necessary. The blood draw is done in the morning after fasting overnight because IGF-1 levels fluctuate during the day with food intake. Certain medications may impact test results, so it is important to tell your doctor about any drugs you are taking.

Understanding IGF-1 Test Results

Normal IGF-1 ranges are age and gender specific. In general, acceptable IGF-1 levels are:

• Teens: 170-500 ng/mL
• Adults: 117-329 ng/mL

The endocrinologist will interpret your IGF-1 result based on your medical history, symptoms and other lab results. An abnormal IGF-1 level may require additional GH testing to confirm a growth or pituitary disorder before starting treatment.

Accessing IGF-1 Testing Near Me

Our extensive national lab network provides easy access to IGF-1 testing across the U.S. Order your test online and get same-day blood draw at one of 4,000+ locations. We work with top labs like Quest Diagnostics to make IGF-1 testing affordable and convenient. Results delivered through our secure portal within 1-3 days.

Tests Included:

Estimated Turn Around For Results:

2-10 Business Days

For an exact turnaround time for results, please contact us at Personalabs and we will contact the lab on your behalf as turnaround times vary depending on testing location or lab testing provider.