Eurofins Biomnis code

OXAU

Synonyms

• Oxalate
• Oxaluria

Specialty

Analytical Chemistry

Clinical significance

Primary hyperoxaluria (genetic) or secondary (acquired) hyperoxaluria can lead to renal calculi. Measuring blood oxalate levels is useful for monitoring patients on renal dialysis. Hyperoxaluria may be primary (a metabolic defect), secondary (due to impaired small intestine function) or toxic (drug-induced or due to over-consumption or accidental ingestion).Oxalic acid is a metabolite of ethylene glycol found in urine and is a good marker for poisoning which can be either deliberate or occupational.

Preanalytics

• 1 tube(s) :
• Acidified 24 hr urine (pH 2-3)
•   Reftrigerated

• A tube specifically for this analysis : No

Further information

The following is essential for the oxalic acid assay:
- 24-hour urine collection, keep refrigerated
- indication of diuresis volume
- acidification of urine by the sampling laboratory by adding hydrochloric acid (HCl) to obtain a urinary pH between 2 and 3.


In practice, urine can be acidified as follows:
- homogenise the entire diuresis very vigorously
- take a urine sample volume of 50 mL
- acidify this urine sample with the help of 6N hydrochloric acid
- homogenise the urine well after each addition of HCl before each pH testing
- measure pH with the help of pH paper or a pH meter.

Specific equipment available

• Tube for urine sample (4mL)-T28

Methodology

Spectrophotometry

Turnaround time

5 days