Oxalate (24 hour urine)
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. 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.
|24h Acid Urine (HCl)
|Weekdays. Assay is run fortnightly.
|Oxalate is derived from dietary oxalic acid, ascorbic acid & glycine metabolism.
|Specialist Laboratory Medicine,
St James's University Hospital,
|Accurately timed 24 hour collection. Sample must be collected into 24 hour urine bottle containing hydrochloric acid. Please contact lab if required. Random sample acceptable for paediatric patients.
|24 hour urine collected into HCl. Record volume and collection period and send 20 mL aliquot. Store at 4C prior to sending.