GROWTH HORMONES

I am sure you may be asking this question, which is indeed a very reasonable question. In childhood growth hormone is important to enable you to grow, and for many years it was not thought to have any other relevance for adults. More recently however, it has become clear that growth hormone is relevant even for adults who have stopped growing.

Patients who lack growth hormone often complain of symptoms such as fatigue, muscle weakness, lethargy, anxiety, feelings of isolation and depression. This is difficult because many people who have normal concentrations of growth hormone also complain of similar symptoms. We shall return to this later! In addition, patients lacking growth hormone have an increased risk of osteoporosis (brittle bones), increased levels of cholesterol and possible an increased risk of early heart disease. One reason for these changes in cholesterol is that such patients have increased amounts of fat tissue around their abdomen (tummy) and smaller amounts of protein/muscle in their legs and arms. This reduction in muscle may partly explain why they feel weaker and have less energy. It also explains why growth hormone deficient patients have poorer exercise performance. The heart is a muscle and in growth hormone deficient patients the heart pumps less forcefully, but whether this has any significance to the patient is unclear at this stage.

IF THIS IS THE CASE, IS THERE ANY BENEFIT TAKING GROWTH HORMONE REPLACEMENT ?

Extensive trials have been undertaken to address whether there is any benefit in giving growth hormone to growth hormone deficient patients. The trials show that after about 9 months bone strength seems to improve and the amount of abdominal fat decreases with a corresponding increase in muscle bulk. This is mirrored by a reduction in blood cholesterol, and it is hoped that this may result in a decrease in the risk of heart disease – although definite proof for this is still awaited. Patients who initially have been severely deficient of growth hormone, often notice an improvement in symptoms. This is manifest by an improvement in muscle strength, improved energy levels, more vitality and better mood. There is no evidence of improvement in such symptoms in patients who are not growth hormone deficient ! Detailed studies have shown improved muscle function and slightly improved heart function. Thus in summary, some patients, probably especially those with severe growth hormone deficiency, may significantly benefit by replacing growth hormone.

Unfortunately it is not possible to determine this on a single blood test. You will need to come into the hospital for part of a day for special blood tests. This involves injecting a hormone into you (either insulin or glucagon usually, although others are sometimes also used) and seeing if the body can respond as normal by releasing enough growth hormone. Blood tests are performed every 30 minutes to look for this growth hormone response.

Growth hormone is a protein which is broken down by the acid in the stomach. Thus unfortunately growth hormone cannot be taken by tablets but has to be taken by injection. Growth hormone is genetically engineered to be identical to human growth hormone and is taken by daily (subcutaneous – ie into the skin) injections into the upper leg or abdomen. Patients are usually started on a low dose which is gradually increased. The final dose depends on your symptoms and special blood tests which monitor the effect of growth hormone on the tissues ("IGF1"). The doses used are generally much lower than are used in children to stimulate growth.

Most patients experience no side-effects. Sometimes, to start with there can be some fluid retention and patients notice swelling of their fingers or feet or joint discomfort. This usually indicates that they are on too high a dose to start with, and the dose needs to be reduced. The doctor will also need to keep an eye on your blood pressure, especially if you are known to have hypertension, since the blood pressure may go up. This is however is only a short-term problem and after several months the blood pressure will usually come down again at least to the original levels and possibly lower. There is a similar problem with blood sugars. For a few months they may go up before ultimately coming down. This may be important however if you have diabetes or borderline diabetes. Some people are concerned that growth hormone may stimulate the growth of tumours. As a result very careful follow-up has been performed over the last 10 years and longer, but to date there is no evidence of any concern, with no increased risk of either new tumours or recurrence of brain tumours. The follow-up studies are continuing to make sure this treatment continues to be safe.

For properly identified patients with well documented growth hormone deficiency, replacement with growth hormone may improve a number of adverse symptoms. In addition it will improve bone strength and reduce blood cholesterol with a reduction of fat tissue. It is hoped that this will be associated with a decrease in heart disease.

Why not contact the Pituitary Foundation at;
PO Box 1944
Bristol, BS99 2UB.
Tel/Fax 0117 927 3355
e-mail- helpline@pitpat.demon.co.uk

Links to

Hypopituitarism

Tests for GH deficiency

Glucagon

Complete Pituitary Function

ITT

Disclaimer; no liability whatsoever is accepted for information given and all such information, especially with regard to drug usage (UK version provided), must be checked with a person’s health provider.