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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Uric Acid for Patients on Rasburicase


CPT Code(s): 84550

Methodology: Uricase

Days Performed: Daily, 24 hours.

Turnaround Time: Stat: 1 hour.
Routine: 2 hours.

Specimen Requirements

Specimen: Blood

Collection Instructions: Sample must be drawn in a pre-chilled tube.  Place sample on ice or coolant pack immediatley after drawing.

Collection Container: Preferred: Green cap with yellow ring (PST)
Also Acceptable: Green top

Collection Volume: Preferred: 1 mL
Pediatrics: 0.4 mL

Sample Analyzed: Plasma

Volume Required: Preferred: 0.5 mL
Pediatrics: 0.2 mL

Specimen Processing: Centrifuge immediately. Transfer cell free plasma to plastic vial. Refrigerate.

Specimen Transport: Transport specimen with coolant pack to UWHC Core Laboratory (B4/220) immediately. Transport with coolant pack if coming from outreach location.  Specimen must be received by laboratory within 4 hours of collection.

Unacceptable Criteria: Samples greater than 4 hours old when received by the UWHC Core Laboratory are not acceptable.

Stability: Refrigerated: 4 hours


Reference Interval:
 Male:    Female:  
 Age  mg/dL  Age  mg/dL
 0-4 years  2.0-5.5  0-4 years  2.0-5.5
 5-11 years  3.0-6.0  5-10 years  2.8-6.0
 12-14 years  3.2-7.5  11-17 years  2.8-6.6
 15 years and up  3.5-8.0  18 years and up  2.5-6.0


Test Limitations:

Must be analyzed within 4 hours of collection. Rasburicase (Elitek) will cause enzymatic degradation of uric acid within blood allowed to sit at room temperature, resulting in low uric acid levels. Sample must then be redrawn.

Additional Information:

As per discussion with the UWHC Pharmacy and the manufacturer of rasburicase, this special collection procedure can be discontinued 4 days after the last dose of rasburicase.

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