Irregular menstrual periods in young women may be a warning sign of a hormonal shortage that could lead to osteoporosis, according to a preliminary study by researchers at the National Institute of Child Health and Human Development (NICHD). The study, of women with a condition known as premature ovarian failure, appears in the May issue of Obstetrics and Gynecology.
Premature ovarian failure occurs when the ovaries stop producing eggs and reproductive hormones well in advance of natural menopause. An estimated one percent of American women develop the condition by age 40.
Most of the women who took part in the study reported a history of amenorrhea-absence of a menstrual period for three months or more-before they were later diagnosed with premature ovarian failure. Moreover, the majority of these young women had not considered amenorrhea as a significant health problem.
"These findings suggest that women and their physicians may want to err on the side of caution and evaluate menstrual irregularities early," said Duane Alexander, M.D., Director of the NICHD.
The NICHD researchers surveyed 48 women with premature ovarian failure, to try to gain an understanding of the early signs of the disorder, according to the study's first author, Nahrain H. Alzubaidi.
The 48 women surveyed visited the National Institutes of Health Clinical Center between September 2000 and June 2001. Most of the women interviewed did not view a change in menstrual pattern as an important health issue and this factor may have contributed to a delay in their receiving a diagnosis of premature ovarian failure.
"Because missed periods are common symptoms in young women, it's understandable that more than half of our patients weren't concerned at first," said the study's senior author, Lawrence Nelson, M.D., of NICHD's Unit on Gynecologic Endocrinology "But the delay in evaluating and treating ovarian insufficiency may place young women at increased risk of developing osteoporosis in later years."
The diagnosis of premature ovarian failure can be problematic, Dr. Nelson said. Although 3 percent of young women will experience amenorrhea in a given year, most of them do not go on to develop premature ovarian failure. Yet by the time they receive a diagnosis, many women with premature ovarian failure experience bone loss serious enough to possibly place them at risk for later bone fractures.
In an earlier study of 89 women with premature ovarian failure, Dr. Nelson and his colleagues had found that 67 percent of the women had already developed osteopenia-the low bone density that precedes osteoporosis. Dr. Nelson said he suspects that the high rate of bone loss in women with premature ovarian failure might be due to a delay in diagnosing and treating the hormonal shortfall that accompanies the disorder.
Osteoporosis results from a loss of bone density, which, in turn, leads to weaker bones that are more likely to break. Estrogen and other reproductive hormones produced by the ovary help to maintain bone density. Although osteoporosis is more common after menopause, younger women who are lacking sufficient ovarian hormone production-particularly those with premature ovarian failure-may also develop the condition.
In the current study, the researchers found that 92 percent of the women with POF reported a change in menstrual cycle as the first symptom they experienced. Moreover, more than half of the women with amenorrhea reported seeing three or more different providers before they received their diagnosis. One fourth of the women did not receive a diagnosis for five or more years after the beginning of menstrual irregularity.
In almost all cases, at least some laboratory testing will need to be performed to determine the cause of the irregular periods, Dr. Nelson said. Typically, tests to detect premature ovarian failure measure the amount of a reproductive hormone in the blood known as follicle stimulating hormone (FSH for short). Treatment for premature ovarian failure usually consists of replacing the missing reproductive hormones estrogen and progesterone.
"It's relatively easy to measure a blood FSH level to detect ovarian failure early," Dr. Nelson said. "When dealing with osteoporosis an ounce of prevention is worth a pound of cure."
The NICHD is part of the National Institutes of Health, the biomedical research arm of the federal government. The Institute sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. NICHD publications, as well as information about the Institute, are available from the NICHD Web site, http://www.nichd.nih.gov, or from the NICHD Information Resource Center, 1-800-370-2943; e-mail NICHDInformationResourceCenter@mail.nih.gov.