Renal phosphate loss in hereditary and acquired disorders of bone mineralization

Three metabolic bone diseases display similar characteristics such as hypophosphatemia due to chronically elevated renal phosphate clearance, inappropriately low 1,25 (OH)2 vitamin D serum levels, and variable bone disease (rickets and osteomalacia). X-linked dominant hypophosphatemic rickets (XLH), also called vitamin D-resistant rickets and autosomal dominant hypophosphatemic rickets (ADHR) represent two inherited diseases, whereas oncogenic hypophosphatemia (OHO), also known as tumor induced osteomalacia (TIO), is an acquired paraneoplastic syndrome that, in certain aspects, has much in common with XLH and ADHR. Although the primary causes for these disorders are distinct and well established, their similar features suggest a unifying pathophysiological basis. This review summarizes what is known about the mechanisms that underlie these diseases and includes most up-to-date information about recently introduced factors that might be involved in the regulation of phosphate homeostasis and skeletal mineralization.