GROWTH HORMONE DEFICIENCY

The pituitary gland is a pea-sized gland located at the base of the brain. It is the body's master hormone gland. It produces many hormones. Hormones are chemical substances that are carried by the bloodstream to every part of the body where they control and coordinate numerous body functions.

Without hormones, our body's functions will be thrown into a state of disorder and dysregulation.

Growth hormone (or somatotrophin) has important regulatory actions on all body tissues. In childhood, it is responsible for linear growth. A child who does not produce sufficient growth hormone fails to grow like his peers. He is shorter and smaller. His puberty may be delayed. Without treatment, he would become a short adult.

In adults, growth hormone has other functions. Such an adult would not become shorter, but often has the following problems:

• Decreased energy levels
• Social isolation
• Lack of positive well being
• Depressed mood
• Increased anxiety
• Increased body fat, particularly central adiposity.
• Decreased muscle mass
• Decreased bone density, with increased risk of fracture.
• Increased LDL cholesterol ('bad' cholesterol) and decreased HDL cholesterol ("good" cholesterol)
• Decreased cardiac muscle mass
• Impaired cardiac function
• Decreased total and extracellular fluid volume.
• Decreased insulin sensitivity and increased prevalence of impaired glucose tolerance and diabetes.
• Accelerated atherogenesis

How does growth hormone deficiency develop?

GH deficiency is a virtually invariable component of hypopituitarism. Hypopituitarism (meaning low pituitary function) is discussed in the section on Hypopituitarism. In childhood GH deficiency, GH lack may be a isolated or solitary defect. Older adults often have low, or lower GH levels because of aging.

Diagnosis

The diagnosis of GH deficiency is made by measuring serum GH concentrations in response to dynamic tests. The gold standard is the insulin tolerance test (ITT). This involves creating low blood glucose readings in a person, and then measuring his GH response. A normal response is a clear rise. An international consensus has now been reached which states that a level of GH < 10 mU/l in response to hypoglycaemia is diagnostic of severe GH deficiency in patients with structural pituitary disease and/or other pituitary deficiencies and/or a history of childhood GHD. The IGF1 test is not sensitive or reliable for diagnosing GH deficiency.

Treatment

Treatment consists of replacing growth hormone. This is done using daily injections of growth hormone. A very small amount of GH is injected under the skin over the abdomen or thigh. The injection is virtually painless. Patients (or parents) will be taught to do this themselves. It is not difficult to learn to do this.

The internet advertises and touts many alternative forms (pills, sprays, potions) of GH replacement. None of these are scientific or effective. None is approved by the Food and Drug Adminstration of the United States. They are a waste of time and money. Some may even be harmful. Only GH injections have been shown to be safe and to work.

What can you expect?

Overall, at least 80% of patients with growth hormone deficiency given growth hormone replacement demonstrate a significant improvement, especially in fat distribution, body composition and parameters reflecting well being and quality of   life. Children with childhood GH deficiency experience an increase in growth velocity, and often catch up with their peers.