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Growth Hormone Tests
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Growth Hormone Tests

Growth hormone (GH) tests measure hormone levels in the blood to diagnose and monitor conditions related to growth and metabolism.

Overview

Growth hormone (GH) tests check if your body is producing the correct amount of GH, which is essential for growth in children and bone and muscle health in adults. Because GH levels fluctuate throughout the day, these tests often measure related proteins and hormones to provide an accurate assessment of pituitary gland function.

GH Disorders

  • GH deficiency: Insufficient GH, which can lead to slowed growth in children and reduced bone density or muscle mass in adults.
  • Gigantism: A rare childhood condition caused by excess GH, leading to excessive height and large hands/feet.
  • Acromegaly: An adult condition caused by excess GH, resulting in thickened bones and enlarged facial features.

Test Procedures

Providers use specific tests based on suspected conditions:

  • GH Stimulation Test (for deficiency): You receive medicine via an IV to stimulate the pituitary gland, followed by blood samples over two hours to see if GH levels rise.
  • GH Suppression Test (for excess): You drink a glucose solution, and blood samples are taken every 30 minutes for two hours to see if GH levels decrease.

Understanding Results

If GH levels fail to increase during a stimulation test, it may indicate a GH deficiency, which can be treated with GH supplementation. If levels fail to decrease during a suppression test, it may indicate GH excess, which is often caused by a pituitary tumor and may require surgery, radiation, or medication.

Additional Testing

Providers may also order:

  • IGF-1 test: Measures a hormone that reflects GH effects and is more stable throughout the day.
  • IGBP-3 test: Measures a protein that carries IGF-1, helping to diagnose deficiency, insensitivity, or excess.

Frequently Asked Questions

Growth hormone is released in short, pulsatile bursts throughout the day rather than at a steady level, meaning a single random blood draw often captures a trough (low point) that does not reflect overall production. Dynamic testing, such as stimulation or suppression tests, involves serial sampling to observe how the pituitary gland responds to specific triggers or inhibitors, providing a much more accurate picture of functional capacity than a static measurement.
Results for the dynamic testing portion are often available within a few days, but the final interpretation may take longer as the endocrinologist correlates the data with other markers like IGF-1 and clinical symptoms. If a deficiency is confirmed, treatment with recombinant human growth hormone injections may be initiated. If excess is found, further imaging like an MRI of the pituitary gland is typically ordered to locate a tumor, followed by a discussion of treatment options including surgery, radiation, or medication.
stimulation test is used to diagnose GH deficiency; it involves administering a medication to prompt the pituitary gland to release GH, and if levels fail to rise adequately, deficiency is confirmed. Conversely, a suppression test is used to diagnose GH excess (such as acromegaly); it involves drinking a glucose solution, which should normally suppress GH production. If GH levels remain high despite the glucose load, it indicates pathological overproduction, often due to a pituitary tumor.
It is generally not recommended to drive yourself to or from a GH stimulation test. The medications used to stimulate the pituitary gland can cause side effects such as dizziness, nausea, flushing, or lightheadedness. Since the test involves an IV and multiple blood draws over a two-hour period, you should arrange for a family member or friend to accompany you and drive you home to ensure your safety.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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