Approximately 80% of filtered phosphorus is reabsorbed by renal proximal tubule cells. The regulation of urinary phosphorus excretion is mainly dependent on regulation of proximal tubu-lar phosphorus reabsorption. Urinary phosphorus excretion is increased by high phosphorus diet, parathyroid hormone, extracellular volume expansion, low dietary potassium intake, proximal tubule defects (eg, Fanconi syndrome, X-linked hypophosphatemic rickets, tumor-induced osteomalacia).
Factors which decrease, or are associated with decreases in, urinary phosphorus excretion include low dietary phosphorus intake, insulin, high dietary potassium intake, and decreased intestinal absorption of phosphorus (eg, phosphate-binding antacids, vitamin D deficiency, malabsorption states).
25 Jul