Métabolisme du phosphore

Phosphate homeostasis is a requirement for normal life. Phosphate is involved in synthesis of membrane lipids, DNA, and RNA molecules, of energy-rich molecules (ATP or GTP), and is implicated in the regulation of protein activity by phosphorylation/dephosphorylation. Moreover phosphate as integrated in apatite crystals provides stability to the bone and is essential for normal growth. The adequate phosphate balance in the organism results essentially from the net summation of net phosphate absorption from intestine and output fluxes through the kidney. Disorders of phosphate metabolism are multiple from genetic and acquired causes. Thus assessing the status of phosphate metabolism in individuals remains a challenge in order to provide adequate care. Besides the measurement of hormones critically involved in the control of phosphate metabolism (parathyroid hormone, vitamin D, fibroblast growth factor 23), assessing the magnitude of phosphate reabsorption by the kidney is a crucial step. It allows to discriminate between a primary disorder of renal phosphate reabsorption, of intrinsic or endocrine origin, and a nutritional cause of phosphate deficiency. This strategy is described and the potential consequences for therapeutic decisions are discussed.