Phosphate excretion in chronic renal failure: evidence for a mechanism other than circulating parathyroid hormone.

Abstract

The mechanism of the increased phosphaturia of chronic renal failure was investigated in seven patients with creatinine clearances ranging from 22 to 63 ml/min. Phosphorus deprivation for 2 to 7 weeks resulted in a marked and rapid reduction in urinary total and fractional phosphate excretion. Serum immunoreactive parathyroid hormone concentration initially remained unchanged and eventually decreased slowly from 330 +/- 50 microliterEq per ml (control) to 252 +/- 58 microliterEq per ml (P less than 0.025), but persisted substantially elevated above the normal range (10-60 microliterEq per ml). Thus, phosphate excretion in chronic renal failure can be regulated to a major extent by the dietary phosphorus intake independently of parathyroid hormone.