Low growth hormone levels due to obesity may raise the risk of heart disease in women who do not have pituitary disease, according to a new study funded by the National Institutes of Health. The preliminary results will be presented Sunday, June 15, at The Endocrine Society’s 90th Annual Meeting in San Francisco.

Doctors already know that abnormally low levels of growth hormone, which the pituitary gland naturally secretes in healthy people, can increase cardiovascular risk in people whose pituitary glands are not working properly. Growth hormone also can be low in people who do not have pituitary problems but are overweight or obese. Therefore, the authors wanted to find out if overweight and obese women who do not have pituitary disease are at increased risk of heart disease.

“Identifying risk factors for heart disease in obese women is important, as it may lead to therapies in the future,” said study co-investigator Karen Miller, MD, an endocrinologist at Massachusetts General Hospital.

Miller and her co-workers studied 45 healthy premenopausal women (ages 18 to 45 years), ranging from thin to obese. The subjects had various tests to determine their level of growth hormone secretion and their risk of heart disease.

These tests included a standard growth hormone stimulation test, which doctors use to determine whether patients with pituitary disease have growth hormone deficiency. The researchers divided the women into two groups, depending on their peak stimulated growth hormone: those with a level less than 5 nanograms per milliliter (ng/mL), which is considered low, and those whose level was greater than 5 ng/mL. They also compared the groups’ average levels of cardiovascular risk markers, using tests that when abnormal predict an increased risk of heart disease.

The authors found that some of the overweight or obese women—but none of the thin women—had growth hormone levels low enough to be classified as growth hormone deficiency (below 5 ng/mL) if they had had pituitary disease. Furthermore, the levels of some risk markers for future heart disease, including high-sensitivity C-reactive protein and HDL (“good”) cholesterol, were generally more abnormal in women with low stimulated growth hormone levels than in the other group.

“Our results raise the possibility that low growth hormone levels in otherwise healthy overweight and obese women may be associated with an increased risk of heart disease,” Miller said.

“However, it is premature to recommend screening for low growth hormone levels in clinical settings,” she said. “We don’t know whether growth hormone therapy in these women would be beneficial or harmful.”

Also, the U.S. Food and Drug Administration has not approved growth hormone therapy for use in people without pituitary disease, she added.

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Founded in 1916, The Endocrine Society is the world's oldest, largest, and most active organization devoted to research on hormones and the clinical practice of endocrinology. Today, The Endocrine Society's membership consists of over 14,000 scientists, physicians, educators, nurses and students in more than 80 countries. Together, these members represent all basic, applied, and clinical interests in endocrinology. The Endocrine Society is based in Chevy Chase, Md. To learn more about the Society, and the field of endocrinology, visit our web site at www.endo-society.org.