Oxalate (Urine oxalate: creatinine ratio)
Oxalate (Oxalic acid) is an organic acid that is a natural end product of metabolism. Exogenous (dietary) sources of oxalate include rhubarb, spinach, nuts and chocolate; ascorbic acid (Vitamin C) is a precursor of oxalate and excessive vitamin C intake can result in increased oxalate excretion. Endogenous synthesis of oxalate occurs in the liver and enzyme deficiencies in this metabolic pathway give rise to the rare inherited disorders Primary Hyperoxaluria (PH) type 1, 2 and 3. Urinary oxalate excretion is markedly elevated in patients with PH. Secondary causes of raised oxalate excretion include high dietary intake of oxalate / oxalate precursors and fat malabsorption (which increases intestinal absorption of oxalate via complex formation between oxalate and free fatty acids). Approximately 90% of oxalate is excreted via the kidneys; when urine oxalate concentration is increased there is increased formation of insoluble calcium oxalate, giving rise to kidney stones.
| Tube | 25 mL universal containing 1mL 4M HCl (preferred) or plain universal container. Contact lab for special container. |
|---|---|
| ID | 29978 |
| Availability | Weekdays. Assay is run fortnightly. |
| Additional Information | Oxalate is derived from dietary oxalic acid, ascorbic acid & glycine metabolism. |
| Turn Around | 20 days |
| Send to | Specialist Laboratory Medicine, Block 46, St James's University Hospital, Beckett Street, Leeds LS9 7TF |
| Collection Con | Collect a fresh random urine into a plain container and transfer immediately to a 25 mL universal containing 1 mL 4M HCl. Alternatively send the plain sample to the laboratory to be acidified on receipt in the laboratory. Samples MUST be received in the lab on the day of collection. |
| Sample REQ | Random acidified urine sample. Instructions for Lab: Transfer plain urine samples immediately upon receipt to a 25 mL universal containing 1 mL 4M HCl. |
| Units | mmol/mmol creatinine |
| Telepath | OXRU1J |
