Glycolate Causes the Acidosis in Ethylene Glycol Poisoning and is Effectively Removed by Hemodialysis

Abstract
Six male patients with severe ethylene glycol poisoning were studied with respect to the origin of the metabolic acidosis. The plasma concentrations of ethylene glycol were 4-41 mmol/l and treatment included alkali, ethanol and hemodialysis. Plasma analysis by isotachophoresis and whole blood lactate determinations showed that glycolate (17.0-29.3 mmol/l), lactate (1.4-6.2 mmol/l) and .beta.-hydroxybutyrate (.ltoreq. 1.8 mmol/l) were present in elevated concentrations contributing to the acidosis. Oxalate (.ltoreq. 0.33 mmol/l) glyoxylate (< 0.02 mmol/l) and formate (< 0.4 mmol/l) concentrations were negligible and did not contribute to any significant degree to the acidosis. The elevated plasma glycolate concentration was highly correlated to the anion gap (r = 0.923) and the glycolate made up for 96.1% (n = 6, range 84.7-108.8) of the increased anion gap. Glycolate accumulation is the main reason for the metabolic acidosis in ethylene glycol poisoning. The mean dialysator (1.6 m2) clearances of glycolate at a blood flow of 200 ml/min in 2 patients were 137 ml/min (n = 9, SD .+-. 8, range 125-149) and 144 ml/min (n = 11, SD .+-. 8, range 133-158). By applying 1st order kinetics during hemodialysis a volume of distribution of glycolate of 0.55 l/kg was found, assuming that the dialysator clearance equals the total body clearance of glycolate. Thus, glycolate, the probable main metabolite of ethylene glycol, is efficiently removed by hemodialysis.