title: Osteo-renal regulation of systemic phosphate metabolism.
abstract: Impaired kidney function and subsequent skeletal responses play a critical role in disrupting phosphate balance in chronic kidney disease (CKD) patients with mineral and bone disorder (CKD-MBD). In patients with CKD-MBD, the inability of the kidney to maintain normal mineral ion balance affects bone remodeling to induce skeletal fracture and extraskeletal vascular calcification. In physiological conditions, bone-derived fibroblast growth factor 23 (FGF23) acts on the kidney to reduce serum phosphate and 1,25-dihydroxyvitamin D levels. In humans, increased bioactivity of FGF23 leads to increased urinary phosphate excretion, which induces hypophosphatemic diseases (e.g., rickets/osteomalacia). However, reduced FGF23 activity is associated with hyperphosphatemic diseases (e.g., tumoral calcinosis). In patients with CKD, high serum levels of FGF23 fail to reduce serum phosphate levels and lead to numerous complications, including vascular calcification, one of the important determinants of mortality of CKD-MBD patients. Of particular significance, molecular, biochemical and morphological changes in patients with CKD-MBD are mostly due to osteo-renal dysregulation of mineral ion metabolism. Furthermore, hyperphosphatemia can partly contribute to the development of secondary hyperparathyroidism in patients with CKD-MBD. Relatively new pharmacological agents including sevelamer hydrochloride, calcitriol analogs and cinacalcet hydrochloride are used either alone, or in combination, to minimize hyperphosphatemia and hyperparathyroidism associated complications to improve morbidity and mortality of CKD-MBD patients. This article will briefly summarize how osteo-renal miscommunication can induce phosphate toxicity, resulting in extensive tissue injuries.
authors: Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA. mrazzaque@hms.harvard.edu
authors: Mohammed Shawkat
authors: MS
authors: Razzaque
mesh_terms: D000818:Animals; D001851:Bone Diseases, Metabolic / Q000150:complications / Q000188:drug therapy / Q000378:metabolism; D001842:Bone and Bones / Q000378:metabolism*; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000378:metabolism; D005966:Glucuronidase / Q000378:metabolism; D006801:Humans; D006961:Hyperparathyroidism / Q000188:drug therapy / Q000209:etiology / Q000378:metabolism; D054559:Hyperphosphatemia / Q000188:drug therapy / Q000209:etiology / Q000378:metabolism; D007668:Kidney / Q000378:metabolism*; D000090265:Klotho Proteins; D010281:Parathyroid Hormone / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D051436:Renal Insufficiency, Chronic / Q000150:complications / Q000188:drug therapy / Q000378:metabolism; D014807:Vitamin D / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: C000717427:FGF23 protein, human; D010281:Parathyroid Hormone; D010710:Phosphates; D014807:Vitamin D; D005346:Fibroblast Growth Factors; C097949:1,25-dihydroxyvitamin D; D000089703:Fibroblast Growth Factor-23; D005966:Glucuronidase; D000090265:Klotho Proteins