“The findings suggest that if you determine that fibromyalgia patients have low magnesium levels, you might want to check IGF-1,” Dr Romano said.
He noted that in referring such patients to an endocrinologist, the results have been consistent.
“When I suspect a patient’s IGF-1 levels are low, I send them to an endocrinologist for confirmation and they will do the intravenous GHRH [growth hormone–releasing hormone]-arginine stimulation test,” he explained.
“The typical response is a peak and then the level comes down, but in the vast majority of fibromyalgia patients it’s just a flat reading, with no response.”
Treatment with growth hormone to restore normal levels typically starts with low dose, 0.2 mg, of subcutaneous injections daily for several months, with increased titration if levels are not restored within several months, Dr Romano said.
Although the study is small, Dr Romano urged clinicians to consider such factors when struggling with fibromyalgia management.
“The take-home message is to keep looking,” he said. “Fibromyalgia patients tend to have numerous comorbidities and they may be related.”
Studies that have also linked IGF-1 levels to fibromyalgia include a randomized, double-blind, placebo-controlled study published in 1997 in the American Journal of Medicine, which showed significant overall improvements in fibromyalgia symptom scores after IGF-1–deficient women were treated with daily growth hormone injections.
The “Future” of Chronic Pain
Pain specialist Forest Tennant, MD, PhD, from the Veract Intractable Pain Clinic in West Covina, California, who has also explored the role of hormones in chronic pain and presented a talk on the topic at the meeting, noted that, aside from the few earlier studies, the role of growth hormone in fibromyalgia has not been extensively explored.
“When it comes to pain, we’re not entirely certain what growth hormone does, but that it affects mainly hard tissue such as bone cartilage,” he told Medscape Medical News.
“But we’ve been extensively studying human chorionic gonadotropin and that looks like it works more importantly in the nervous system and really seems to be becoming an essential compound.”
“I’m glad they’re studying this, however, because [hormone involvement] is the future of chronic pain, there’s no question about it.”
Dr Romano has disclosed no relevant financial relationships. Dr Tennant receives speaker’s bureau fees from Ethos Labs, Regenesis Biomedical, and INSYS Therapeutics.