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Order Code LAB937 Orotic Acid, Random, Urine

Additional Codes

Mayo Test Code: OROT

Reporting Name

Orotic Acid, U

Useful For

Evaluation of the differential diagnosis of hyperammonemia and hereditary orotic aciduria

 

Sensitive indicator of ornithine transcarbamylase (OTC) activity after administration of allopurinol or a protein load to identify OTC carriers

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Urine


Necessary Information


1. Patient's age is required.

2. Provide a reason for testing.



Specimen Required


Supplies: Urine Tubes, 10 mL (T068)

Container/Tube: Plastic, 10-mL urine tube

Specimen Volume: 10 mL

Collection Instructions:

1. Collect a random or timed urine specimen.

2. No preservative needed.


Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Frozen 30 days

Reference Values

<2 weeks: 1.4-5.3 mmol/mol creatinine

2 weeks-1 year: 1.0-3.2 mmol/mol creatinine

2-10 years: 0.5-3.3 mmol/mol creatinine

≥11 years: 0.4-1.2 mmol/mol creatinine

Day(s) Performed

Tuesday, Thursday

CPT Code Information

83921

Method Description

Interfering substances such as amino acids, urea, pigments, and creatinine are removed from the urine by passing it through a cation-exchange resin. The orotic acid is then brominated to form dibromobarbituric acid, reduced to barbituric acid with ascorbic acid, and finally condensed with dimethylaminobenzaldehyde to form 5(p-dimethylaminobenzaldehyde)-barbituric acid. The absorbance of the final product is measured at 480 nm using a control reaction as reference.(Harris ML, Oberholzer VG. Conditions affecting the colorimetry of orotic acid and orotidine in urine. Clin Chem. 1980;26[3]:473-479); Cowan T, Pasquali M. Laboratory investigations of inborn errors of metabolism. In: Sarafoglou K, Hoffman GF, Roth KS, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. McGraw-Hill; 2017:1139-1158)

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Method Name

Colorimetric