Skip to main content

Preferred Sample Type

Urine Oxalate

Suitable Specimen Types

  • 24 Hour Urine (Acid Collection)
8 mL aliquot of 24hr urine

Specimen Transport

First Class Post

Sample Processing in Laboratory

Usual

Sample Preparation

Aliquot sample of 24 hour collection into universal container. Store sample frozen. Note on request form date, volume and period of collection.

Turnaround Time

10 working days

Sample Stability

Store frozen

Urine Oxalate

General Information

Oxalate in urine may arise either as an end-product of the metabolism of ascorbic acid and amino acids (especially glycine) or from dietary sources (e.g. rhubarb, spinach, tea). Hyperoxaluria leads to the formation of highly insoluble calcium oxalate which has a tendency to precipitate out in the renal medulla and urine leading to urolithiasis.

There are two forms of primary hyperoxaluria. Type I hyperoxaluria is associated with an increase in urine glycolate caused by deficiency of the peroxisomal enzyme alanine : glyoxylate aminotransferase (AGT). Patients present in the first decade of life with recurrent calcium oxalate nephrolithiasis. Type II hyperoxaluria is associated with an increase in urine L-glyceric acid caused by deficiency of the cytosolic enzyme D-glycerate dehydrogenase. Survival of these patients appears to be better than those with type I hyperoxaluria.

Hyperoxaluria may also occur secondary to inflammatory bowel disease or malabsorption. This may be due to a reduction in the levels of calcium in the gut, as the ionised calcium ion concentration is a limiting factor in oxalate absorption and low levels promote oxalate absorption.

 

Patient Preparation

None

Notes

From 10/05/2018, specimens sent to HSL, London for analysis.

NB: urine oxalate results now reported as umol/24hrs not mmol/24hrs

Reference Range

From 10/5/2018 refernce ranges will be:

100 - 460 umol/24 hour (adults, correct to 1.73m2for children)

Age related ref ranges for oxalate:creatinine ratio:

0-6 months  <291µmol/mmol

7-23 months  <220µmol/mmol

2-4 years  <143µmol/mmol

5-11 years  <76µmol/mmol

12 -17 years  <44µmol/mmol

18+ female    <45µmol/mmol

18+ male       <33µmol/mmol

Specifications

  • EQA Scheme?: Yes
  • EQA Status: WEQAS