When doing research to elucidate the cause of fibromyalgia, some studies uncovered links between fibromyalgia and imbalances of certain hormones. These studies suggest that there may be a link between various hormonal imbalances and fibromyalgia, whether these imbalances are a cause or an effect of the chronic pain condition. The evidence is conflicting, however, so more research is required on this topic.
The first studies that postulated hormonal imbalance in fibromyalgia patients were based on the fact that fibromyalgia was more common in women than it was in men. Since one major difference between men and women is the sex hormones, these hormones were investigated. Women have more of a hormone called estrogen, produced by the ovaries, and men have more hormones called androgens, a category which includes testosterone, which are produced by the testes. Women have testosterone too, just a lot less of it than men do. The results of the studies looking at estrogen’s role in fibromyalgia were inconclusive, and it is not likely that estrogen levels play a large role in the development of fibromyalgia. Lower androgen levels in women may play a larger role, because hormones like testosterone affect muscle growth, but this is yet to be determined.
Another group of hormones that researchers have looked at in terms of fibromyalgia are the “stress hormones” cortisol and norepinephrine. Some fibromyalgia patients have lowered levels of cortisol. This is consistent with the observation that if a person is deprived of cortisol, symptoms such as fatigue, muscle weakness, muscle aches, sleep disturbances and cognitive impairments develop. These are all symptoms that are present in fibromyalgia. However, the importance of cortisol levels in producing the symptoms of fibromyalgia patients is unknown. Unfortunately, giving fibromyalgia patients cortisol to correct their low levels of this hormone does not appear to be an effective treatment for fibromyalgia. No link has been established between fibromyalgia and norepinephrine (adrenaline) levels.
Some studies have noted that about 30 percent of fibromyalgia patients have low levels of a particular growth hormone, called IGF-1. IGF-1 acts on muscle tissue and bones to promote their growth. Decreased growth hormone levels also lead to fibromyalgia symptoms, such as fatigue, cold intolerance, muscle weakness and memory and concentration problems. However, this link is not present in a majority of fibromyalgia patients, and the correlation between growth factor hormones and fibromyalgia may not be strong.
One practical application of the knowledge of hormone imbalances in fibromyalgia patients would be the use of blood tests for hormones as a diagnostic marker of fibromyalgia. Fibromyalgia is difficult to diagnose, because many of the symptoms can be caused by other conditions that must be ruled out before a diagnosis can be made. If markers for fibromyalgia existed in the blood, however, this would simplify the diagnostic process and could serve as a confirmatory test for diagnosis of fibromyalgia. Other conditions can also cause hormonal imbalances, as well, so the test would not be specific for fibromyalgia, but it could still help narrow things down. The problem is that not all fibromyalgia patients exhibit low levels of hormones, so the test would not be reliable enough for diagnostic use. The correlations found in these hormone studies are still being investigated, and other studies have contradicted the results.
Replacement of hormones that are low in fibromyalgia patients, including cortisol and growth factor IGF-1, does not appear to be an effective treatment for fibromyalgia symptoms. There are obviously other factors that contribute to the development of fibromyalgia that are more important than the hormonal abnormalities present in some fibromyalgia patients. However, it may turn out that hormonal imbalances are at least part of the answer to the questions that we have about fibromyalgia. More research is necessary to determine to what extent the hormonal abnormalities found in many fibromyalgia patients affect the course of the disease, and whether effective fibromyalgia treatments or diagnostic procedures could come from this line of research.