Oxalate retention in chronic renal failure: tubular vs glomerular diseases.

Plasma oxalate concentration was measured using an enzyme/bioluminescent assay in 289 patients (178 males, 111 females) with chronic renal failure (plasma creatinine greater than 200 mumol/l), age (SD) 55.5 (13.8) years. Plasma oxalate ranged between less than 0.8 and 48 mumol/l and showed a positive correlation with plasma creatinine (r = 0.57, p less than 0.0001). The slope of the regression line in 55 patients with glomerulonephritis (GN) was significantly lower than in patients with tubulointerstitial disease (TI); however the intercept was significantly higher in GN than in TI. Analysis of covariance showed no relationship between plasma oxalate concentration and age, duration of renal impairment, or administration of diuretics, vitamin D analogues, or phosphate binders. Longitudinal analysis of plasma oxalate measured 3-monthly in selected patients showed marked variability of oxalate/creatinine and oxalate/urea ratios.