Osteoporosis is generally thought of as a condition unique to women, but it also affects a considerable number of men. The causes of osteoporosis in men include hypogonadism, glucocorticoid excess, medications and lifestyle factors. Osteoporosis results in a significant number of hip and vertebral fractures in men. Currently, no treatments have been labeled by the U.S. Food and Drug Administration for osteoporosis in men, although testosterone therapy has been shown to be somewhat beneficial. Orwoll and colleagues recently evaluated the use of alendronate in men with decreased bone mineral density (BMD). This agent inhibits osteoclastic-mediated bone resorption and decreases osteoporotic fractures of the spine and hip in postmenopausal women.
Two hundred forty-one men between 31 and 87 years of age were enrolled in the study. They had a BMD at the femoral neck of at least two standard deviations (SD) below the mean value for normal young men or a BMD of at least one SD below the mean plus at least one vertebral deformity or a history of an osteoporotic fracture. Men with secondary causes of osteoporosis, except low serum free testosterone, were excluded. Participants found to have a low testosterone level at baseline had the test repeated and, if the value was less than 0.09 ng per mL (0.31 nmol per L), were offered testosterone therapy. The men were then randomly assigned to receive 10 mg of alendronate or placebo daily for up to two years. In addition, all participants took 500 mg of calcium and 400 IU of vitamin D daily.
The patients returned for follow-up visits at three, six, 12, 18 and 24 months. Height was measured at each visit. BMD of the lumbar spine, hip and total body were measured at baseline and again at the six-, 12-, 18- and 24-month follow-up visits. Anteroposterior radiographs of the lumbar spine, hip and total body were measured at baseline and at the end of two years.
In the study, 146 men were assigned to the alendronate group and 95 to the placebo group. In both groups, 36 percent had low serum free testosterone levels at baseline, and approximately 50 percent had vertebral fractures. At the end of two years, the BMD of the lumbar spine increased by a mean of 7.1 percent, the femoral neck by 2.5 percent and the total body by 2.0 percent in the men who took alendronate. In those in the placebo group, the BMD of the lumbar spine increased by a mean of 1.8 percent, but no changes occurred in the femoral neck or total body. The observed benefits of alendronate on BMD were independent of age and baseline serum testosterone levels.
At the end of two years, the men in the placebo group had lost an average of 2.4 mm in stature compared with 0.6 mm in the alendronate group. This change was significant. Finally, the incidence of vertebral fractures was 7.1 percent in the placebo group but only 0.8 percent in the alendronate group. Ten of the men in the placebo group withdrew because of side effects, and four withdrew from the treatment group. The frequency of reported adverse gastrointestinal side effects was 36 percent in the placebo group and 41 percent in the alendronate group.
The authors conclude that alendronate increases BMD of the total body, spine and hip in men with osteoporosis. In addition, alendronate reduces the rate of vertebral fractures and prevents a decrease in overall height after two years of daily therapy.