Osteoporosis in men - New insights into aetiology, pathogenesis, prevention and management

Osteoporosis is increasingly recognised in men. Low bone mass, risk factors for falling and factors causing fractures in women are likely to cause fra ctures in men, Bone mass is largely genetically determined, but environment al factors also contribute. Greater muscle strength and physical activity a re associated with higher bone mass, while radial bone loss is greater in c igarette smokers or those with a moderate alcohol intake. Sex hormones have important effects on bone physiology, In men, there is no abrupt cessation of testicular function or 'andropause' comparable with th e menopause in women; however, both total and free testosterone levels decl ine with age. A common secondary cause of osteoporosis in men is hypogonadi sm. There is increasing evidence that estrogens an important in skeletal ma intenance in men as well as women. Peripheral aromatisation of androgens to estrogens occurs and osteoblast-like cells can aromatise androgens into es trogens, Human models exist for the effects of estrogens on the male skelet on, In men aged >65 years, there is a positive association between bone min eral density (BMD) and greater serum estradiol levels at ail skeletal sites and a negative association between BMD and testosterone at some sites. It is crucial to exclude pathological causes of osteoporosis, because 30 to 60% of men with vertebral fractures have another illness contributing to b one disease. Glucocorticoid excess (predominantly exogenous) is common. Gas trointestinal disease predisposes patients to bo ne disease as a result of intestinal malabsorption of calcium and colecalciferol (vitamin D). Hyperca lciuria and nephrolithiasis, anticonvulsant drug use, thyrotoxicosis, immob ilisation, liver and renal disease, multiple myeloma and systemic mastocyto sis have all been associated with osteoporosis in men. It is possible that low-dose estrogen therapy or specific estrogen receptor -modulating drugs might increase BMD in men as well as in women. In the fut ure, parathyroid hormone peptides may be an effective treatment for osteopo rosis, particularly in patients in whom other treatments, such as bisphosph onates, have failed. Men with idiopathic osteoporosis have low circulating insulin-like growth factor-1 (IGF-1, somatomedin-l) concentrations, and IGF -1 administration to these men increases bone formation markers more than r esorption markers. Studies of changes in BMD with IGF-I treatment in osteop orotic men and women are underway. Osteoporosis in men will become an increasing worldwide public health probl em over the next 20 years, so it is vital that safe and effective therapies for this disabling condition become available. Effective public health mea sures also need to be established and targeted to men at risk of developing the disease.