IDIOPATHIC OSTEOPOROSIS - A HETEROGENEOUS ENTITY

Definition. - Idiopathic osteoporosis refers to the development of ost eopenia and fractures with minimal or no trauma in otherwise young, he althy individuals who are not postmenopausal or have other, identifiab le secondary causes of osteoporosis. Epidemiology. - It is a relativel y rare disorder, with an incidence of 0.4 cases per 100000 person-year s. It appears to affect both sexes equally and results primarily in th e development of trabecular bone fractures such as vertebral compressi on fractures and Colles' fractures, although hip fractures are also se en. Pathophysiology. - The disease may be temporally related to pregna ncy and/or lactation in some patients, although it is unclear whether pregnancy plays a pathophysiological role or, more likely, simply lead s to the clinical presentation of the disease in individuals who are a lready affected. Various pathophysiological abnormalities have been de scribed in these patients, including hypercalciuria, abnormalities in vitamin D metabolism, and in the production of insulin-like growth fac tor I and interleukin 1. Findings on bone biopsy have been variable, w ith some patients having evidence of a defect in osteoblast function, whereas others having evidence for increased bone resorption, Treatmen t. - No specific therapy has been proven to be effective in these pati ents. However, an individualized approach based on an assessment of bo ne turnover may be reasonable and may decrease the bone loss and subse quent fracture risk.