Renal handling of inorganic sulfate in children with chronic kidney disorders.

Excretion, clearance and tubular reabsorption of inorganic sulfate (SO4) were measured in 38 children with various chronic kidney disorders over a wide range of glomerular filtration rates (GFR). The SO4 excretion remained constant up to advanced renal failure. Significant correlations were found between GFR and clearance or tubular reabsorption of SO4, respectively. It appears that in early renal insufficiency the reduction of tubular SO4 reabsorption is sufficient to prevent an increase in plasma SO4. At GFR values below 30 ml/min/1.73 m2 about half of the children studied exhibited a net tubular secretion of SO4 and all patients showed a rapid increase of plasma SO4 up to 10 times mean normal levels. It is suggested that the accumulation of SO4 in uremia is less compensated for than that of other ions.