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Tracking FSH Annually Said to Help Predict Bone Loss in Perimenopause


 

Tracking follicle-stimulating hormone levels every year from premenopause onward can help predict bone loss during the menopausal transition, reported MaryFran R. Sowers, Ph.D., of the University of Michigan, Ann Arbor, and her associates.

The researchers conducted what they described as the first study to longitudinally characterize bone mineral density (BMD) loss at the spine and hip in conjunction with changes in reproductive hormone concentrations. They found that the interaction between the baseline FSH level obtained before menopause and serial FSH levels taken every year thereafter predicted bone loss. However, this interaction “is complex, requires at least two FSH values, and may be challenging to apply in a busy clinical setting,” they cautioned.

The study population comprised 2,311 women aged 42–52 at baseline who were assessed at several medical centers across the United States for 5 years. Half of the women were white, 28% were African American, 11% were Japanese, and 11% were Chinese.

The women underwent annual spine, femoral neck, and total hip BMD assessments with densitometers. Blood samples obtained annually during the early follicular phase of the menstrual cycle were analyzed for estradiol, FSH, testosterone, sex hormone-binding globulin (SHBG), and dehydroepiandrosterone sulfate (DHEAS) content.

At baseline, 53% of the women were classified as premenopausal because they reported no decrease in menstrual regularity during the preceding year, and 47% were classified as being in the “early perimenopausal” period because they reported decreased menstrual regularity in the preceding 3 months (J. Clin. Endocrinol. Metab. doi:10.1210/jc.2005/1836, published Jan. 10, 2006).

The interaction between baseline FSH levels and subsequent levels predicted bone loss. “If baseline FSH was lower (<25 mIU/mL), then statistical modeling indicated that more lumbar spine change occurred only when the follow-up FSH concentrations were higher (40–70 mIU/mL), and the greatest amount of spine BMD loss (−0.05 g/cm

“However, if the baseline FSH was higher (35–45 mIU/mL), then modeling indicated that lower levels of follow-up FSH (40–50 mIU/mL)” predicted a decrease in spine BMD, the investigators said. They devised charts to show predicted bone loss for various levels of baseline and subsequent FSH.

Estradiol levels measured throughout this transitional period “were poor predictors of incremental BMD change,” Dr. Sowers and her associates noted.

Similarly, there was no correlation between BMD changes and levels of testosterone, DHEAS, or SHBG.

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