Insulin-like Growth Factor 1 (IGF-1)

The Insulin-like Growth Factor 1 (IGF-1) test measures the level of IGF-1 in the blood. IGF-1 is a hormone similar to insulin that plays a key role in childhood growth and continues to support anabolic effects in adults. IGF-1 is primarily regulated by growth hormone (GH), and its measurement is useful for evaluating growth disorders and GH-related conditions.

1. What Is IGF-1?

• IGF-1 is a hormone produced by the liver in response to stimulation by growth hormone (GH).

• It helps regulate bone and tissue growth and is involved in metabolism and cell repair.

• IGF-1 levels are relatively stable throughout the day, making it a reliable marker of GH activity.

2. Why Is the IGF-1 Test Performed?

This test is used to:

• Evaluate growth disorders in children (e.g., short stature, delayed growth).

• Diagnose and monitor conditions such as acromegaly and gigantism (excess GH).

• Detect GH deficiency in adults or children.

• Monitor GH therapy effectiveness.

3. IGF-1 Reference Ranges

• Normal IGF-1 levels vary significantly by age, sex, and pubertal stage.

• Lab reports typically provide age-specific reference ranges.

• Low IGF-1 may suggest GH deficiency; high IGF-1 may indicate GH excess.

4. Interpreting IGF-1 Test Results

🔹 High IGF-1:

• May indicate GH overproduction (e.g., acromegaly or gigantism).

• Can also be seen in pregnancy or with GH therapy.

🔹 Low IGF-1:

• May suggest GH deficiency or insensitivity, malnutrition, or chronic disease.

• Can occur with hypothyroidism, liver disease, or poorly controlled diabetes.

5. What Can Affect IGF-1 Levels?

• Age, puberty, and sex hormones

• Nutritional status and chronic illness

• Liver function (IGF-1 is produced in the liver)

• Use of GH therapy or anabolic steroids

6. How Is the Test Performed?

• A blood sample is drawn from a vein.

• Fasting is usually not required, though your provider may request it based on other tests.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have abnormal growth patterns in childhood.

• Are experiencing symptoms of GH imbalance (e.g., enlarged hands/feet, facial changes, fatigue).

• Are being treated for GH-related disorders and need monitoring.

🔹 Key Takeaways

✅ IGF-1 is a stable and reliable indicator of GH activity in the body.

✅ Testing is useful for diagnosing growth hormone excess or deficiency.

✅ Results must be interpreted in context of age, health status, and other hormone levels.