title: In vitro synthesis of oxalic acid has no relevant influence on plasma oxalic acid levels in haemodialysis patients.
abstract: Plasma oxalic acid concentrations were measured in 13 chronic haemodialysis patients. The mean plasma oxalic acid concentration was 128.0 +/- 48.6 mumol/l, being approximately 8 times higher than the plasma concentration of 14 volunteers (mean = 16.8 +/- 5.2 mumol/l). Ultrafiltrates obtained in vivo from these patients showed a mean oxalic acid concentration of 138.2 +/- 56.5 mumol/l. Since in vivo ultrafiltrates are free of erythrocytes and plasma enzymes, an in vitro synthesis of oxalic acid from precursors by erythrocytes and plasma enzymes can be excluded. As the oxalic acid concentration of plasma corresponded to that of in vivo ultrafiltrates, it is concluded that any in vitro formation of oxalic acid in haemodialysis patients must be negligibly small, and is irrelevant for the measurement of plasma oxalic acid levels in patients receiving regular haemodialysis.
mesh_terms: D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D010070:Oxalates / Q000096:biosynthesis / Q000097:blood*; D019815:Oxalic Acid; D006435:Renal Dialysis; D014462:Ultrafiltration
chemical_list: D010070:Oxalates; D019815:Oxalic Acid