Growth Hormone (GH)
A blood test that measures growth hormone levels to assess pituitary function and diagnose growth hormone deficiency or excess.
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What this test measures
Growth hormone (GH), also known as human growth hormone (HGH) or somatotropin, is a natural hormone produced by the pituitary gland in the brain. In children, GH promotes growth and development by stimulating the secretion of insulin-like growth factor-1 (IGF-1) from the liver. Once the growth plates in bones have fused and individuals reach adult height, GH continues to play important roles in maintaining normal body structure, metabolism, and healthy blood glucose levels.
The pituitary gland releases growth hormone in short bursts or pulses throughout the day and night, with the largest releases typically occurring during deep sleep. Because GH secretion occurs in this pulsatile manner, a single random test may not provide a complete picture of an individual's growth hormone status. IGF-1 testing is often considered alongside GH testing, as IGF-1 levels remain relatively stable throughout the day and are not influenced by food intake, making it a more reliable indicator of overall GH activity.
Who should consider this test
You might consider this test if you are experiencing any of the following:
- Individuals experiencing unexplained fatigue, decreased muscle mass, or changes in body composition, as these symptoms may be associated with growth hormone deficiency in adults.
- Those with concerns about pituitary function, particularly individuals who have had brain surgery, radiation therapy, or head trauma that could affect the pituitary gland.
- Patients with a family history of pituitary disorders or those who have been diagnosed with other hormone deficiencies that may indicate broader pituitary dysfunction.
- Individuals being evaluated for potential acromegaly or gigantism, conditions associated with excessive growth hormone production that can cause abnormal growth patterns.
- Adults with unexplained changes in bone strength, cardiovascular risk factors, or cholesterol levels, as growth hormone plays a role in bone metabolism and cardiovascular health.
What to expect
Preparation
Fasting for 8-12 hours before the test is recommended. Complete rest for at least 30 minutes before blood collection is required to minimize stress-related hormone fluctuations. Inform the healthcare provider about any medications, especially biotin supplements, which should be discontinued 72 hours before testing.
Sample Type
A simple blood draw from a vein in the arm, similar to other routine blood tests. The sample will be collected in a specialized tube and processed in the laboratory.
Collection
The blood collection takes only a few minutes and is performed by trained phlebotomists at the lab location. No special equipment or extended monitoring is required for this basic GH measurement.
Turnaround
Results are typically available within 1-3 business days after the sample reaches the laboratory.
Understanding your results
Random growth hormone measurements can vary significantly due to the pulsatile nature of GH secretion, which is why single measurements are rarely sufficient for diagnosing growth hormone disorders. More specialized stimulation or suppression tests may be needed for definitive diagnosis. Results should always be interpreted by a healthcare provider in the context of symptoms and clinical presentation.
| Population | Reference Range | Notes |
|---|---|---|
| Adult Males | 0.4-10 ng/mL (18-44 pmol/L) | Normal random levels for healthy adult men |
| Adult Females | 1-14 ng/mL (44-616 pmol/L) | Normal random levels for healthy adult women |
| Children | 10-50 ng/mL (440-2200 pmol/L) | Normal random levels for children and adolescents |
Reference ranges may vary by laboratory and individual factors. Results should be interpreted by a healthcare provider in the context of your overall health.
What does a “Low” result mean?
Low growth hormone levels may be associated with growth hormone deficiency, which can cause slow growth rates in children and symptoms such as fatigue, decreased muscle mass, changes in cholesterol levels, and reduced bone strength in adults. In children, insufficient GH secretion can lead to impaired linear growth and may cause delayed sexual maturity in adolescents. However, because growth hormone is released in pulses, low random levels may also represent normal physiological patterns and require confirmation through stimulation testing.
What does a “High” result mean?
Elevated growth hormone levels may indicate the possibility of gigantism in children or acromegaly in adults, conditions often caused by pituitary adenomas. In children, this can lead to excessive growth and very tall stature, while in adults it may cause enlargement of hands, feet, and facial features. Elevated levels may also be found in certain nutritional disturbances such as anorexia, starvation, or chronic liver or kidney disease. Confirmation of growth hormone excess typically requires additional suppression testing.
Privacy & confidentiality
Your growth hormone test results are completely confidential and protected under HIPAA regulations. Results will not be shared with your personal physician unless you specifically request it, will not be added to your medical records, and will not appear on insurance explanation of benefits. Access your secure results online with complete privacy.
Frequently asked questions
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IGF-1 (Insulin-Like Growth Factor-1)
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CPT Code: 83003
This test may not be available in: NY, NJ, RI
This page is for informational purposes only and does not constitute medical advice. Always consult with a healthcare provider regarding any health concerns. LevelPanel does not diagnose, treat, or prescribe.
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Not sure if this is the right test? Contact our care team for guidance.