What do growth hormones have to do with Fibro

A lack of growth hormone is not something that immediately springs to mind when thinking of fibromyalgia. After all, FM isn’t associated with shortness — so what has growth hormone got to do with it? Actually, quite a bit. Growth hormone is responsible for much more than just our height.

Growth hormone is vital for repairing and restoring any damage that occurs to our muscles and tissues during the normal rigors of everyday life. It stimulates the production of new proteins to repair tiny muscle tears (microtraumas) and replace worn-out tissues that have passed their sell-by date, so to speak. A constant lack of growth hormone means these repairs are overlooked and left to pile up over time, leading to discomfort and pain. If your body were a car, this would be like never getting it properly serviced.

Growth hormone also has a role during exercise: it bathes our cells and tissues in a soothing solution, helping make us feel good after a workout—not sore and tender. This important hormone is stored in and released from the pituitary gland in the brain. The pituitary gland is prompted to release growth hormone by a messenger secreted by a control center in the brain called the hypothalamus. Once in the bloodstream, growth hormone stimulates the liver to release its working partner IGF-1 (insulin-like growth factor 1). It is IGF-1 that carries out the hard work of telling the body to repair and restore the muscles and tissues.

THE FIBRO CONNECTION TO GRWTH HORMONE

Researchers first took an interest in growth hormone and fibro back in the early 1990s. They noticed that adults deficient in growth hormone had symptoms similar to fibromyalgia, like low energy, muscle weakness, cold intolerance, impaired cognition, and a reduced capacity to exercise. In 1992, Robert Bennett, MD, and Sharon Clark, MD, from Oregon Health and Science University in Portland, Ore., found significantly lower levels of IGF-1 than normal in the majority of the 70 female FM patients they tested1. They found similar results when they looked at another 500 FM patients in 1972, and decided to start investigating whether growth hormone therapy could treat fibromyalgia.

The results were promising, and soon other research teams in Europe followed along the same path. Recently a research team led by Albert Nadal, MD, from the Servicio de Endocrinología y Nutrición in Barcelona, found that when a group of 24 FM patients were treated with a low dose of growth hormone, the number of their tender points reduced by 60 percent. These patients also reported an improved quality of life, with their fibromyalgia symptoms having less impact on their daily activities. Response to the growth hormone injections was rapid, with most patients showing improvements within the first few months.

Patrick Summers, who was diagnosed with fibromyalgia in 1990, had a similar response to growth hormone injections when he started using them a year ago. “The growth hormone immediately made me feel better by seeming to boost my metabolism,” he says. “I found I was no longer sensitive to the cold. Usually when I went to bed I had to have an electric blanket around my lower legs and feet, but now I have had to take it off my bed as I get too warm with it on! I also feel more vigorous, and cramping restless legs syndrome-like symptoms I used to experience frequently have gone away.”

Summers went to a private clinic in California to have his growth hormone levels tested and be prescribed injections. “Regular medical doctors will not prescribe human growth hormone because using it to treat fibromyalgia is an off  label use,” he told me, “and for the same reason, my health insurance does not cover it.” And this brings us to one of the major drawbacks of growth hormone therapy: the expense. In the original trial by Bennett and Clark, most of the FM patients involved were not able to continue treatment after the study, despite an improvement in their symptoms, because they simply could not afford it.

Summers pays about $330 per month, which adds up to a little under $4000 per year. “It is far less expensive than when Dr. Bennett carried out his first study, but the cost is still high,” he says. “But is it worth $4000 a year to get my life back? Undoubtedly, yes.”

THEORIES FOR GH DEFICIENCY

So what causes growth hormone to be low in fibromyalgia? Well, there are several theories. Firstly, around 80 percent of growth hormone is thought to be released during deep sleep, a stage of sleep shown to be disrupted in some fibromyalgia patients by the intrusion of light sleep waves, called alpha waves. The principal researcher in this field, Harvey Moldofsky, MD, from the University of Toronto in Canada, suggests that this disruption is responsible for the non-refreshing sleep and muscle pain of fibromyalgia. Interestingly, when Moldofsky deprived healthy volunteers of deep sleep, they too developed similar FM-type symptoms, which only resolved following a night of undisturbed sleep.

The other theory involves the hormone somatostatin, the main role of which is to inhibit growth hormone release. Growth hormone is the only pituitary hormone to receive both stimulatory and inhibitory signals from the hypothalamus, and it is the balance of these signals that determines whether or not growth hormone is released. It is becoming evident that levels of somatostatin are higher than normal in FM patients, which could explain the low levels of IGF-1 reported. Bennett’s research team has carried out some interesting studies to test this theory.

They have compared growth hormone release in response to exercise in FM patients and healthy volunteers. As expected, the Fibro patients’ response was significantly lower than the healthy volunteers’, but all this changed when the Fibro patients took a drug called pyridostigmine one hour before the exercise program. Pyridostigmine works by inhibiting somatostatin, and the result was an improved growth hormone response for the FM patients. A recent trial by Bennett’s team, published in Arthritis and Rheumatism in February 20087, looked at using pyridostigmine to clinically treat FM.

They compared FM patients treated with pyridostigmine and exercise with another group of FM patients receiving a placebo and doing exercise. The results revealed that the combination of pyridostigmine and exercise did not improve pain scores, but did significantly improve sleep and anxiety when compared to the placebo group. Pyridostigmine was generally well tolerated by the participants and Bennett’s team believes it certainly warrants further study.

Growth hormone therapy shows promise in successfully treating some of the symptoms of fibromyalgia; however, at present it is unlikely to feature in regular fibromyalgia treatment programs due to the cost and the difficulty in obtaining it. Further research could determine whether pyridostigmine offers a more realistic option than regular growth hormone injections, so keep an eye out for further developments in this intriguing line of research.

Kathy Longley is a freelance health writer and the editor for FMA UK’s section of the UK fibromyalgia magazine, FaMily.

Growth hormone is vital for repairing and restoring any damage that occurs to our muscles and tissues during the normal rigors of everyday life.

QUICK FACT

Adults deficient in growth hormone have symptoms similar to fibromyalgia, like low energy, muscle weakness, cold intolerance, impaired cognition, and a reduced capacity to exercise.