Oxalate Analysis in Hemodialysate
Determining the amount of oxalate removed during a dialysis session
Individualizing the dialysis prescription of hyperoxaluric patients
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Oxalate is a dicarboxylic acid, an end product of glyoxalate and glycerate metabolism that is excreted in the urine where it is a common component of kidney stones (up to 85%). Hyperoxaluria can be either genetic (eg, primary hyperoxaluria) or acquired/secondary (eg, enteric hyperoxaluria), and can lead to nephrocalcinosis and renal failure. Monitoring the adequacy of oxalate removal during hemodialysis can be useful in the management of patients with hyperoxaluria and renal failure, particularly following transplantation.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
A steady decrease in oxalate signal is expected through dialysis procedure.
Signals below 2 mcM should be considered ideal conditions.
Total oxalate removed during a dialysis session can be estimated by multiplying the concentration of oxalate in the dialysate by the oxalate flow rate for each time period that the oxalate is measured.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Proper specimen processing and acidification are essential to obtain a quality result and avoid nonenzymatic generation of oxalate from ascorbate.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Canavese C, Petrarulo M, Massarenti P, et al: Long-term, low-dose, intravenous vitamin C leads to plasma calcium oxalate supersaturation in hemodialysis patients. Am J Kidney Dis 2005 Mar;45(3):540-549
2. Koch GH, Strong FM: Determination of oxalate in urine. Anal Biochem 1969 Jan;27(1):162-171
3. Marangella M, Petrarulo M, Mandolfo S, et al: Plasma profiles and dialysis kinetics of oxalate in patients receiving hemodialysis. Nephron 1992;60(1):74-80
4. Marangella M, Vitale C, Petrarulo M, et al: Bony content of oxalate in patients with primary hyperoxaluria or oxalosis-unrelated renal failure. Kidney Int 1995;48(1):182-187