Diagnosis of Primary Hyperoxaluria Type 1 by Determination of Peritoneal Dialysate Glycolic Acid Using Standard Organic-Acids Analysis Method

Abstract

Objective Hyperglycolic hyperoxaluria is an important biochemical diagnostic hallmark for primary hyperoxaluria type 1 (PH1). Biochemical work-up on urinary specimens becomes impossible after the development end-stage renal failure and anuria. We studied the diagnostic value of determining glycolic acid content in peritoneal dialysate effluent in PH1. Patients and Methods We performed a comparative study on an anuric continuous ambulatory peritoneal dialysis (CAPD) patient whose PH1 was confirmed by genetic study and on 5 anuric CAPD controls. Specimens were taken from each bag of peritoneal dialysate effluent over a 24-hour period, and the corresponding drainage volume was noted. The specimens were then processed using standard procedures for organic-acid analysis. They underwent ethyl acetate extraction, followed by semiquantitative analysis of organic acids by gas chromatography mass spectrometry (GCMS). The daily output of glycolic acid in peritoneal dialysate for each individual was then estimated. Results All 6 patients were receiving four 2-L CAPD exchanges daily. The estimated daily glycolic acid output for the PH1 patient was 48.3 μmol daily. The mean glycolic acid output for the 5 controls was estimated to be much lower at 19.6 μmol daily (range: 15.1 – 27.5 μmol daily). Conclusion Standard organic-acid analysis for glycolic acid in peritoneal dialysate could be a useful initial screening tool before invasive or sophisticated testing is done in CAPD patients with suspected PH1.