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Test Code LAB10181 Uric Acid - 24 Hour Urine



Collection Requirements

24 hour urine.

Do not add preservatives to the collection container.

Keep the container on ice or refrigerated during collection.

Note total urine volume and PH on the label.

Primary Collection Container

24 HR Urine container



Preferred Transport Temperature



Keep specimen refrigerated until processing.

Check pH.

If pH is <8 treat entire 24 hr urine with 5% NaOH and allow to sit for 15 min.

Re-check the pH and continue to add NaOH until the pH is >8.

Centrifuge, aliquot and refrigerate.

Note total urine volume and PH on the label.


Ambient: 4 days

Refrigerated: 4 days

Frozen: 6 months

Minimum Testing Volume

0.1 mL

Reference Range

0.5 – 1.1 gm/24hr


The uric acid method is a modification of the uricase method first reported by Bulger and Johns1, later modified by Kalckar.2 Uric acid, which absorbs light at 293 nm, is converted by uricase to allantoin, which is nonabsorbing at 293 nm. The change in absorbance at 293 nm due to the disappearance of uric acid is directly proportional to the concentration of uric acid in the sample and is measured using a bichromatic (293, 700 nm) endpoint technique. Measurement of uric acid by monitoring the loss of absorbance at 293 nm following uricase treatment is generally recognized as being more specific and less subject to interference than other indirect methods. Siemens Diemension Vista.


Sunday – Saturday

7:00 am – 3:00 pm


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CPT Codes