[The various forms of osteoporosis and their treatment]

Age-associated bone loss is transiently accelerated by the menopause and can lower bone mass below the threshold of mechanical resistance. The appearance of fractures allows the clinical diagnosis of osteoporosis (OP). In addition to age and menopause, major causal factors of OP are low peak bone mass in young adults for genetic or nutritional reasons, and inadequate nutrition in advanced age. Endocrine and digestive diseases, corticotherapy, physical inactivity and low body weight are among other additional causes sometimes calling for specific treatment. Postmenopausal OP predominantly involves trabecular bone, leading to vertebral fractures as early as the age of about 60. Men are 6 times less frequently involved. Age-related bone loss also involves cortical bone and causes fracture of the proximal femur at the age of about 80 in both sexes. Fracture of the forearm chiefly affects women after the menopause. Absorptiometry allows quantitative evaluation of demineralization, diagnosis of "osteopenia" in the absence of fractures, and monitoring of follow-up. It permits few conclusions regarding parts of the skeleton other than those measured. Lumbar and femoral absorptiometry is the most useful, followed by that of the forearm. The clinical relevance of laboratory tests is still debated. Treatment consists either of drugs stimulating bone formation (fluoride, possibly anabolic steroids), or of drugs inhibiting bone resorption (calcitonin, possibly bisphosphonates, or estrogens in postmenopausal women, whenever possible in combination with progestational agents), associated with calcium and vitamin D (according to age and cause of OP), together with physiotherapy if necessary.(ABSTRACT TRUNCATED AT 250 WORDS)