| Theme | Hyperphosphatemia | |
|---|---|---|
| Title | Biological role of phosphate and its homeostasis | |
| Publish Date | 2002/01 | |
| Author | Eiji Ishimura | Department of Nephrology, Osaka City University Graduate School of Medicine |
| Author | Yoshiki Nishizawa | Department of Metabolism, Endocrinology, and Molecular Medicine, Osaka City University Graduate School of Medicine |
| [ Summary ] | Phosphate is a constituent of hydroxyapatite of the bone, having an important role in supporting the body. Fourteen percent of total body phosphate is present in the cells; and there, phosphate plays an essential role in the survival of the cells, not only by being a constituent of cell membranes in the form of phospholipid, but also having pivotal cellular functions such as energy production and signal transduction. Hence, the human body possesses a strong protective function, which prevents phosphate depletion. Phosphate depletion is prevented mainly by the kidney through reabsorption of filtered phosphate in the proximal tubulus, where PTH and a decrease in phosphate regulates the reabsorption of phosphate through type II Na-Pi cotransporters. When excessive phosphate is loaded into the body, the kidney with normal renal function, can easily excrete excessive phosphate, even if the serum phosphate concentration far exceeds the TmP/GFR. However, if the renal function has deteriorated, phosphate cannot be adequately excreted in the urine, frequently causing hyperphosphatemia. Hyperphosphatemia causes several metabolic abnormalities in the body, such as those in the bone and parathyroid gland. |
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