Allopurinol Challenge Test (Timed Orotic Acid Test)

Sunquest Code:ALLO  
Epic Code:LAB3008Epic Name:Allopurinol Challenge
Order Instructions:Lab staff should order one test code ALLO for all specimens.
Synonyms:Orotic Acid
Methodology:Gas chromatography/Mass spectrometry
CPT Code:----------CPTCODES HERE----------
Turnaround Time:Performed once per week; results are reported the next day.

Collection Instructions

Specimen:Urine, 5 timed collections
Optimal Volume:Submit entire collection; analysis requires 2 mL.
Collection Instructions:Urine is collected for orotic acid following administration of one dose of allopurinol: 100 mg (1-6 years), 200 mg (6-10 years), or 300 mg (10 years to adult) allopurinol. Caution: Allopurinol should not be given to pregnant women. Collect a random pre-dose specimen and four 6-hour timed collections (0-6 hours, 6-12 hours, 12-18 hours, and 12-24 hours.

Processing and Shipping

Specimen Processing:Mix each collection well before aliquot is taken. Aliquot 10 mL, 2 mL minimum of each timed collection into a separate aliquot tube. Please indicate time of each container. Store in freezer.
Shipping Instructions:Ship on dry ice.
Test Performed at or Referral Lab Biochemical Genetics  (UMMC-East Bank)


Reference Range:



6 hours post


12 hours post


18 hours post


24 hour post



<100 mmol/mol cr/24 hours




Use:Aids in the diagnosis of OTC deficiency and other urea cycle defects associated with orotic aciduria (HHH syndrome, argininemia, lysinuric protein intolerance).

Click HERE to Report test errors or omissions.
*If no email program is associated with this computer, please contact: for TestID: 4375"