OXALATE, 24 HOUR URINE

Code
900.5450
Name
OXALATE, 24 HOUR URINE
Category
None
Department
Send-Out
Start Date
Expiration Date
Synonyms
CPT Codes
83945
Site
SBMF
Reference Test
44045
ATLAS Test Code

Specimen Information

Type

Urine, 24 Hour (No preservative)

Volume

4.0 mL aliquot from well-mixed 24-hour collection

Transport Info

Refrigerated

Fasting Required?
False
Patient Instructions

Since vitamin C (ascorbic acid) quickly degrades to oxalate in nonacidified urine, patients should consider refraining from vitamin C supplements during and for 48 hours prior to urine collection for oxalate.
To begin collection of timed specimen, have patient urinate, noting date and exact time
Discard this first portion of urine, but document date and time of voiding on container label and test requisition as "start" of timed specimen
Save all urine voided during designated time period, including portion voided at exact end of time period
IMPORTANT: Refrigerate entire specimen (2-8°C) during and after collection to prevent bacterial growth
Document date and time of final voiding on label and requisition as "end" of timed specimen

Reference Range

See report

Methodology

Spectrophotometry

Clinical Significance

Formation of the sparingly soluble calcium oxalate salt in the urinary tract is a major factor in urolithiasis. Oxalate in urine may arise either as an end-product of intermediary metabolism or from dietary sources. A decreased excretion of oxalate in the urine is associated with hyperglycinemia and hyperglycinuria. An increased excretion of oxalate can be attributed to increases in ingestion of oxalate precursors or oxalate-rich foods, formation of oxalate due to metabolic defects such as in primary hyperoxaluria, and oxalate absorption in a number of gastrointestinal disorders of severe fat malabsorption. This latter group includes patients with bowel disease, ileal resection, biliary diversion, pancreatic insufficiency, sprue, small intestinal stasis with bacterial overgrowth, and following jejunoileal bypass or bowel resection for the treatment of obesity. Since vitamin C (ascorbic acid) quickly degrades to oxalate in non-acidified urine, patients should consider refraining from vitamin C supplements 48 hours prior to and during urine collection for oxalate.

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