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.
From 10/05/2018, specimens sent to HSL, London for analysis.
NB: urine oxalate results now reported as umol/24hrs not mmol/24hrs
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
The laboratories at Heartlands Hospital, Good Hope Hospital and Solihull Hospital form part of the services provided by University Hospitals Birmingham and are UKAS (United Kingdom Accreditation Service) accredited to the ISO 15189:2012 standard. For a list of accredited tests and other information please visit the UKAS website using the following link: https://www.ukas.com/find-an-organisation/
Tests not appearing on the UKAS Schedule of Accreditation currently remain outside of our scope of accreditation. However, these tests have been validated to the same high standard as accredited tests and are performed by the same trained and competent staff.
For further test information, please visit the test database: http://www.heftpathology.com/frontpage/test-database.html.
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