Idiopathic or Hypogonadal Osteoporosis in Men

Abstract

Osteoporosis is being recognized increasingly in men, and represents a substantial public health problem. As the male population ages and lives longer, the incidence of osteoporotic fractures is expected to increase. The current lifetime risk for a fragility fracture is approximately 27% in men aged 50 years or more, and will increase further over the next 20 years. A major problem with osteoporosis in men is that it continues to be unrecognized, and the majority of men with fragility fractures due to osteoporosis are not being treated. A higher level of awareness is required amongst both general practitioners and the general public that osteoporosis is a treatable condition that can affect men. Secondary causes for osteoporosis are more common in men than in women, and require rigorous exclusion and treatment. Undiagnosed clinical hypogonadism is a common cause of osteoporosis in men, and is readily treatable. The cause of primary osteoporosis in men is unknown, but it results in an osteoblast defect. Genetic factors are likely to be important. In some but not all men, relative estrogen deficiency contributes to rapid rates of age-related bone loss and fractures. An adequate calcium intake, regular weight-bearing exercise, and normal vitamin D status are all very important, particularly with increasing age. The role of testosterone in treating eugonadal men with osteoporosis is currently unclear, and larger prospective studies will be required to carefully evaluate the benefits and risks of therapy. First-line treatment of osteoporosis in hypogonadal or eugonadal men is with bisphosphonates. Alendronate increases bone density and reduces vertebral fractures measured using a semiquantitative method in eugonadal or hypogonadal men with osteoporosis. In the near future, it is likely that subcutaneous human parathyroid hormone (1-34) or teriparatide will also be available as an important new anabolic treatment for men with osteoporosis. Teriparatide treatment also increases bone density in men. Selective estrogen receptor modulating drugs require further evaluation in men, but would appear to theoretically benefit men, especially those with low estradiol levels. In the future, selective androgen receptor modulating drugs may be useful in the prevention and treatment of osteoporosis, and in increasing lean body mass in men, without having adverse effects on prostate and breast tissue.