Sufferers of fibromyalgia and chronic fatigue syndrome may see significant relief from their symptoms when administered the stress hormone cortisol, finds a new study.

A review of 50 published studies conducted by researchers in California has found that people who suffer from chronic fatigue and fibromyalgia have adrenal dysfunction, meaning their adrenal glands, which produce sex hormones and cortisol, don't work effectively.

Chronic fatigue is a condition in which people have debilitating fatigue that may be get worse with activity and is not relieved by rest. Fibromyalgia is a syndrome characterized by multiple pain points in muscles throughout the body and fatigue. Chronic fatigue and fibromyalgia affect 0.5 to five per cent of the population, according to the study's authors.

"My review of existing studies suggests that a treatment protocol of early administration of cortisol may help improve and reduce the symptoms of chronic fatigue syndrome and fibromyalgia," said Dr. Kent Holtorf, medical director of the Holtorf Medical Group Center for Endocrine, Neurological and Infection Related Illness in Torrance, Calif., in a release.

Holtorf also conducted an observational study with 500 patients from his clinic, who received cortisol as part of their treatment. He found that by the fourth visit, 84 per cent reported improvement, with 75 per cent showing "significant improvement," and 62 per cent reporting substantial improvement.

The typical dose of cortisol adminstered to patients was 5 to 15 mg. Concentrations in the body were measured throughout the study using urine analysis.

"Cortisol treatment carries significantly less risk and a greater potential for benefit than treatments considered to be the standard of care for both conditions," said Holtorf.

The study is published in the winter issue of the Journal of Chronic Fatigue Syndrome.