The determination of plasma oxalate concentrations using an enzyme/bioluminescent assay.
An enzyme/bioluminescent assay for the determination of oxalate in plasma is described in which NADH, a reaction product of the enzymic degradation of oxalate by oxalate decarboxylase and formate dehydrogenase, is determined using a commercially available bioluminescent system. In contrast to most previously documented methods, this sensitive and specific assay requires minimal sample preparation allowing oxalate concentrations to be determined within 2 h of sample collection. The limit of detection for plasma samples is 0.8 mumol/l. The recovery of oxalate added to plasma averaged 99%. The inter-batch coefficient of variation, calculated by analysis of a plasma sample from a uraemic patient (oxalate concentration = 45.8 mumol/l) on 8 occasions, over a period of 5 wk, was 3.2%. Plasma oxalate concentrations in 35 normal subjects ranged from less than 0.8-1.5 mumol/l, which is in excellent agreement with values obtained by in vivo isotope dilution studies. Plasma oxalate was found to be strikingly elevated in a group of uraemic patients maintained on regular haemodialysis.
D000328:Adult; D002138:Calibration; D002262:Carboxy-Lyases; D005260:Female; D005560:Formate Dehydrogenases; D006801:Humans; D008156:Luciferases; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D009243:NAD / Q000032:analysis; D010070:Oxalates / Q000097:blood*; D019815:Oxalic Acid; D006435:Renal Dialysis; D013048:Specimen Handling; D013696:Temperature; D014511:Uremia / Q000097:blood
D010070:Oxalates; D009243:NAD; D019815:Oxalic Acid; D008156:Luciferases; D005560:Formate Dehydrogenases; D002262:Carboxy-Lyases; C021915:oxalate decarboxylase