Growth Hormone

Growth hormone (GH) is a protein made in the pituitary gland and passed from there into the blood stream. GH has effects on virtually all the organs of the body, but its primary use during childhood is making children grow. In adults it affects a range of metabolic processes and quality of life.

GH deficiency is usually caused by damage to the pituitary gland or the part of the brain which controls this gland (the hypothalamus). The damage may be due to a tumour, the effects of treatment for the tumour (surgery or radiotherapy) or to problems with the blood supply to the pituitary gland.

Typical symptoms

There are a range of symptoms that affect people with growth hormone deficiency, you may not experience all of these:

• increase in adipose (fatty) tissue (especially around the waist)
• decrease in lean body mass (muscle)
• decrease in strength and stamina, reduction in exercise capacity
• decrease in bone density, increase in rate of fracture in middle age and beyond
• changes in blood cholesterol concentrations (increase in LDL and decrease in HDL)
• excessive tiredness
• anxiety and depression
• feelings of social isolation
• reduction in ‘quality of life’
• increased sensitivity to cold or heat

Diagnosis

Dynamic function testing: Diagnosis is made by assessment of symptoms, and by dynamic function testing. For this test you will have a blood test taken. Then you will have insulin, or glucagon if you can’t have insulin. A blood test will be taken again. Both of these have effect on your blood sugar and there should be a corresponding rise in measured growth hormone over the 2-4 hours following administration.

Macimorelin test: this is a much newer test, and is easier and less stressful. The test takes 90 minutes from start to finish. You will be given an oral suspension (liquid dosage), with blood samples taken at 45, 60 and 90 minutes.

Treatment

Treatment may be trailed in line with NICE Technology Appraisal 64.

Treatment will generally be offered for trial when:

• You have been tested by Growth Hormone Deficiency.
• All other deficient hormones have been replaced and are at stable levels for at least 3 months
• The Adult Growth Hormone Deficiency ‘Quality of Life Questionnaire’ reveals significantly impaired quality of life.

Treatment is given by a self-administered injection, using an injection pen device, similar to those used by diabetic patients. The needle size is small in both length and width, usually 5mm. The amount injected each day is also very small with starting doses usually at 0.2mg/day for adults. Your Endocrine team will arrange for training for you on how to use the pen and how to give your growth hormone injection. Follow up blood tests of IGF-1 will be taken to ensure your dose is right for you. Any adjustments to the injected dose will be made. Growth hormone would not be given if there was current or new tumour growth. IGF-1 levels above expected range for your age may mean you stop your replacement and have a reassessment.

You will be on the medication as a trial for around 6-9 months to see if you have an improvement in quality of life.