what is the best way to measure growth hormone
The best way to measure growth hormone is through a blood test. Specifically, a doctor may order a test called an insulin-like growth factor 1 (IGF-1) test, which measures the amount of a hormone called insulin-like growth factor 1 in the blood. This hormone is produced in response to growth hormone and is a good indicator of growth hormone levels in the body. In some cases, a doctor may also order a growth hormone stimulation test, which involves measuring growth hormone levels before and after the administration of a medication that stimulates growth hormone production. This test is more invasive than the IGF-1 test and is usually reserved for cases where the IGF-1 test results are inconclusive or there is reason to suspect a growth hormone deficiency. It is important to talk to a doctor about the best way to measure growth hormone in your specific case.
Insulin-like growth factor 1 (IGF-1) test: This blood test measures the amount of insulin-like growth factor 1 in the blood. IGF-1 is produced by the liver in response to growth hormone and is a good indicator of growth hormone levels in the body. According to the Endocrine Society’s Clinical Practice Guideline on Adult Growth Hormone Deficiency, an IGF-1 level below the age-adjusted reference range may suggest growth hormone deficiency (1). However, it is important to note that there are many factors that can affect IGF-1 levels, such as age, sex, nutritional status, liver function, and other medical conditions, so the interpretation of IGF-1 test results can be complex.
Growth hormone stimulation test: This test involves measuring growth hormone levels before and after the administration of a medication that stimulates growth hormone production. There are several types of growth hormone stimulation tests, but the most commonly used test is the arginine and insulin tolerance test (ITT) (2). During the arginine stimulation test, the patient is given an infusion of arginine, an amino acid that stimulates growth hormone release. Blood samples are taken before and after the infusion to measure growth hormone levels. During the ITT, the patient is given an injection of insulin to lower blood sugar levels, which stimulates growth hormone release. Blood samples are taken before and after the injection to measure growth hormone levels.
The Endocrine Society recommends the use of growth hormone stimulation tests to confirm the diagnosis of growth hormone deficiency in adults with low IGF-1 levels and clinical features suggestive of growth hormone deficiency (1). However, it is important to note that growth hormone stimulation tests can be expensive, time-consuming, and require close monitoring of the patient’s blood sugar levels, as the insulin injection used in the ITT can cause hypoglycemia in some patients.
References:
Molitch ME, Clemmons DR, Malozowski S, et al. Evaluation and treatment of adult growth hormone deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011;96(6):1587-1609.
Vance ML. Diagnostic tests for adult GH deficiency. Pituitary. 2007;10(3):189-196.
