Renal phosphate handling in nephrotic syndrome during water immersion

In 11 patients suffering from nephrotic syndrome, renal phosphate handling was studied in water immersion up to the neck. There was a rapid onset of phosphate diuresis which continued to increase throughout water immersion; and an increase in fractional excretion of phosphate (FEPO4) continuing throughout immersion and decreasing in the hour after immersion. TmPO4/GFR did not change on immersion. TmPO4/Inulin clearance gave higher figures than TmPO4/creatinine clearance due to secretion of creatinine in 9 of 11 patients. There was a transitory increase in PTH during immersion, but mean immersion plasma levels of PTH did not change when compared to preimmersion control values. FEPO4 was more frequently significantly correlated with FECL than to FENa in nephrotics.