Growth hormone deficiency in adults

Growth hormone deficiency in adults is caused by a low level or lack of production of growth hormone also called somatropin. This is normally produced by the pituitary gland at the base of the brain.

Effects of growth hormone on adult health
In children, growth hormone stimulates growth. Adults also need growth hormone to help maintain a healthy body. For example, growth hormone helps to regulate the amounts of fat, water and muscle in the body. It also affects the composition of the bone and cholesterol levels in the blood. In addition, growth hormone influences our general wellbeing. Individuals who are deficient in growth hormone may feel depressed, anxious, irritable, low in energy and require more sleep than normal.

Treatment
Replacement of the missing natural growth hormone with an injection of synthetic growth hormone can help to reverse the changes brought about by deficiency. This is similar to the treatment of diabetes with insulin, and the management of menopausal symptoms with hormone replacement therapy (HRT).

What causes growth hormone deficiency in adults?
Growth hormone deficiency in adults can be due to either childhood or adult onset.  Some children who have growth hormone deficiency will continue to lack the hormone in adulthood - these children may need to continue growth hormone replacement as adults.

With adult onset, growth hormone deficiency is usually the result of treatment of tumours in areas of the brain near the pituitary gland or the hypothalamus (a part of the brain that controls the pituitary’s output). Surgery or radiotherapy on these parts of the brain may result in damage so that the brain no longer produces the amount of growth hormone the body requires to function normally. Occasionally, accidents in which the brain is damaged may also lead to reduced levels of growth hormone being produced.

What are the symptoms of growth hormone deficiency?
Growth hormone deficiency affects different people in different ways. You may experience many symptoms or just a few, depending on the amount of growth hormone being released by the pituitary gland into the bloodstream. Some of the most common symptoms reported by people with growth hormone deficiency are shown in Table 1.

Table 1. Symptoms of GH Deficiency in Adults

In the long term, untreated growth hormone deficiency may lead to a number of increased health risks: reduced bone density can increase the risk of fractures, especially in older people; metabolic disorders that lead to increased fat also lead to an increased risk of diabetes and heart disease. There is a beneficial change in bone mineral density with treatment.

How is growth hormone deficiency in adults diagnosed?
If your doctor suspects you may have growth hormone deficiency, either because you had it as a child or because you have had surgery or radiotherapy, you will be sent to a specialist endocrine centre to have your hormone levels measured.

Testing for growth hormone deficiency
The amount of growth hormone in the blood is difficult to measure because the body produces it in varying quantities throughout the day and night (most is produced at night). The most common test used in adults is called the insulin tolerance test. Insulin indirectly stimulates the production of growth hormone, and the amount released can be compared with people who do not have growth hormone deficiency. If you are receiving treatment, you may need to have your hormone levels checked from time to time so that the doctors are sure you are receiving the correct dose.

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