Causes of secondary osteoporosis.

Primary osteoporosis associated with menopause and aging is by far the most frequent metabolic bone disease. However, there are many patients who present with secondary osteoporosis due to identifiable causal factors and many others in whom a secondary factor contributes to the severity or progression of primary osteoporosis. Recognition of these secondary causes is particularly important for the prevention of further vertebral fractures, which are often progressive in secondary osteoporosis. This review will summarize the major factors that cause secondary osteoporosis and will discuss their pathogenetic mechanisms. While the most frequent cause is glucocorticoid excess, a number of other diseases, as well as drugs and nutritional deficiencies, can cause secondary osteoporosis. It is important to identify secondary osteoporosis both because of the differences in clinical expression due to different pathogenetic mechanisms and because there are often effective interventions that can add to the more general approach used in primary osteoporosis.