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.
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 or to the effects of treatment for the tumour (surgery or radiotherapy) or to problems with the blood supply to the pituitary gland.
GH is produced by the pituitary gland which is controlled by the hypothalamus. It controls growth in children and is involved in the maintenance of normal body weight, muscle and bone strength and well-being in adults. GH deficiency in adults can result in loss of energy, fatigue and depression, which can lead to a decreased quality of life. If you have not been diagnosed with GH deficiency and feel extremely tired for no apparent reason, you should talk to your doctor or nurse.
The aim of GH treatment is to improve your quality of life and well-being, although there are additional health related benefits from this treatment. The GH used is known as recombinant human growth hormone (rhGH) which is a synthetic preparation. It is recommended that GH should be used to treat adults older than 25 years when they suffer from GH deficiency and a severely affected quality of life. The criteria are:
- You should have a peak GH level of less than 9 mU/litre in an insulin tolerance test, or another reliable dynamic test.
- Your quality of life is severely affected (impaired) by GH deficiency. This is measured using a questionnaire called Quality of Life Assessment of Growth Hormone Deficiency in Adults or AGHDAQoL and you should answer YES to 11 or more of the 25 questions.
- You should already be receiving replacement for any other deficiencies of pituitary hormones if you have one or more other deficiencies, and these should be optimal before GH is started.
After starting GH, your quality of life is assessed nine months later and you are expected to have a 7-point improvement on the AGHDA-QoL questionnaire compared to the pre-GH score. Should this be the case, you will be advised to continue on lifelong GH treatment, unless your individual circumstances change and/or GH is contraindicated. If your quality of life has not improved at all within 9 months (taking into account that you had no other major negative events in your life during this time), you will be asked to stop your GH treatment.
Adult patients younger than 25 years, who are diagnosed with GH deficiency, should be given GH treatment until peak bone mass is achieved (this is at around 25 years old and is measured with a Bone Mineral Density scan). Continuation of GH past peak bone mass is based on the assessment of the quality of life as per above points.
Treatment start and long term monitoring
Before starting your GH treatment, you will normally have a consultation with an endocrine specialist nurse (or an endocrinologist), who will explain what this treatment involves, its purpose, long-term monitoring and then they will organise your treatment start. Many hospitals offer patients the choice of which GH device they would like while others simply prescribe the GH of their choice. The main point to remember is that it is the device that is different and the medicine is the same i.e. Recombinant GH. The average starting GH dose for an adult is 0.2 – 0.3 mg daily.
GH is given by injection into the fatty tissue just under the skin (subcutaneous). Ideally, the injection is performed in the evening to mimic natural GH production which happens during sleep. A lot of patients are very worried at the idea of self-injecting, but with reassurance and training from your nurse, this fear can be overcome. There are helpful aids which come with most devices to make the process easier for the individual. You will be seen in the endocrine clinic at regular intervals, especially during the first 9 months, to assess your response to treatment and to make adjustments to your GH dose according to your needs. The blood test performed measures Insulin-like Growth Factor 1 (IGF-1) which will guide your GH dose increase. IGF-1 is a protein mainly produced by the liver under GH stimulation; severe GH deficiency is often associated with low IGF1. You should ensure that IGF-1 is part of your routine endocrine check- up, as it is the only way to know if you are taking the right dose of GH.
As IGF-1 can drop if you have missed a number of GH doses prior to your blood test, it is very important that you do not miss any injections (or if you do, you should point this out to your clinician so IGF-1 results can be interpreted accordingly). Overdosing with GH and exceeding normal range for IGF-1 can lead to unpleasant side effects and complications.
Support services for GH treatment
As a patient on GH treatment, you should have access to an endocrinologist and an endocrine specialist nurse who will advise you and monitor your treatment. In addition, most pharmaceutical companies producing GH sponsor home services (their name can vary depending on the GH brand) which provide a wide range of support services for patients on GH treatment. When starting your treatment, an endocrine nurse can visit you at your home to train you on the injection device and teach you how to do your injections. Home service will provide you, free of charge, with your treatment starter pack (injecting device, needles, sharps boxes etc), information on GH treatment (on-line, DVD and in print format) and continuous supplies of your needles, sharps boxes etc (also known as “stores”); most of them will also collect clinical waste from your home at the time of stores delivery. Home service can also dispense your GH which will be delivered to your house on a regular basis. Patients find this a great service as they do not have to attend their GP practice and local chemist for repeat prescriptions on a monthly basis. Finally, most home services have a helpline which you can ring if you have any concerns regarding your treatment, for example, if you need a new supply of needles or your pen device is not working.
Needle pen devices As the name states, these devices resemble a pen in which the GH vial is inserted. Injections are relatively painless and the needle is very thin and short. The single-use needle is attached to the front of the pen. Pen devices are re-usable and can last for three to four years.
Needle free devices:
Some patients, have needle phobia and are unable to overcome the fear of needles and cope with injections. There are two needle free devices for GH. These devices inject GH by creating a fine stream of high pressure jet liquid into the subcutaneous (fat) tissue without the use of a needle.
For patients with a genuine fear of needles, these are excellent devices and can improve patient adherence to treatment.