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Alternate test name

Oxalic acid, plasma

Lab area
Clinical Biochemistry - Metabolic Diseases
Method and equipment
Stable isotope dilution Gas Chromatography - Mass Spectrometry (GC-MS)
Expected turn-around time
3 weeks
Specimen type


Specimen requirements

1 mL acidified plasma collected in a Green Top Lithium Heparin tube only. See special requirements for processing instructions. 

Storage and transportation
  • Store at -20°C and transport frozen on dry ice.
Special requirements
  • Patient should be fasting for a minimum of 12 hours and should avoid taking Vitamin C supplements for 24 hours prior to the draw.
  • Collect specimen and place immediately on wet ice.
  • Complete the following steps within 30 minutes from time of collection. 
    • Centrifuge for 10 minutes at 2,000 rpm in a refrigerated centrifuge (4°C).
    • Remove the plasma to a clean plastic vial.
    • Add 20 µL of concentrated HCl for every 1 mL of plasma. Cap and vortex-mix the tube. Final pH on plasma should fall between 1 to 3.5 and should be written on the tube.
    • Freeze immediately and store @ -20°C 
Shipping information
The Hospital for Sick Children
Rapid Response Laboratory
555 University Avenue, Room 3642
Toronto, ON
M5G 1X8
Phone: 416-813-7200
Toll Free: 1-855-381-3212
Hours: 7 days/week, 24 hours/day
Background and clinical significance

This test is useful for the monitoring of kidney function for patients with hyperoxaluria, a condition that may result in kidney stone formation, nephrocalcinosis, progressive kidney damage and systemic calcium oxalate deposition.

Disease condition
  • Primary hyperoxaluria type I (PH I)
  • primary hyperoxaluria type II (PH II) and primary hyperoxaluria type III (PH III)
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