GH (growth hormone) test: what it is for and how it is done

Growth hormone, also called GH or somatotropin, is an important hormone produced by the pituitary gland that plays a role in the growth of children and adolescents and also participates in the body’s metabolic processes.

This test is carried out by measuring blood samples collected in the laboratory and is usually requested by the endocrinologist when there is a suspicion of a lack of GH production, especially in children who have below-expected growth, or of its excess production, common in cases of gigantism or acromegaly.

The use of GH as a medication is indicated when there is a deficiency in the production of this hormone, in children or adults, as indicated by the doctor. To learn more about how growth hormone is used, prices and effects, check out the GH hormone leaflet.

What is it for

The GH test is requested if you suspect:

• Dwarfism, which is a deficiency of growth hormone in children, causing short stature. Understand what it is and what can cause dwarfism;
• GH deficiency in adultscaused by a production of GH below normal, which leads to symptoms such as fatigue, increased fat mass, decreased lean mass, decreased ability to exercise, reduced bone density and increased risk of developing cardiovascular diseases;
• Gigantismcharacterized by excess GH secretion in children or adolescents, causing exaggerated growth;
• Acromegaly, which is a syndrome caused by excess GH production in adults, causing changes in the appearance of the skin, hands, feet and face. See also the differences between acromegaly and gigantism;

The lack of GH in the body can have several causes, such as genetic diseases, brain changes, such as tumors, infections or inflammation or as a side effect of brain chemotherapy or radiotherapy, for example. Excess GH usually occurs due to a pituitary adenoma.

How is done

The dosage of the GH hormone is done by analyzing a blood sample in the laboratory and is done in 2 ways:

1. Basal GH dosage: it is done with at least 6 hours of fasting for children and 8 hours for teenagers and adults, which analyzes the amount of this hormone in the morning blood sample;
2. GH stimulation test (with Clonidine, Insulin, GHRH or Arginine): is done with the use of medications that can stimulate the secretion of GH, in case of a suspected lack of this hormone. Then, analyzes of the GH concentration in the blood are carried out after 30, 60, 90 and 120 minutes of using the medicine.

The GH stimulation test is necessary because the production of the GH hormone by the body is not uniform, and can be interfered by several factors, such as fasting, stress, sleep, sports or when the amount of glucose in the blood drops. Thus, some of the medications used are Clonidine, Insulin, Arginine, Glucagon or GHRH, for example, which stimulate or inhibit the production of the hormone.

In addition, the doctor may also request other tests, such as the measurement of hormones such as IGF-1 or the IGFBP-3 protein, which change with variations in GH: Magnetic resonance imaging of the brain, to evaluate changes in the pituitary gland, as well. may be helpful in identifying the cause of the problem.