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Interpretive Handbook

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Test 81420 :
Purine and Pyrimidine Panel, Urine

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Purines (adenine, guanine, xanthine, hypoxanthine) and pyrimidines (uracil, thymine, cytosine, orotic acid) are involved in all biological processes, providing the basis for storage, transcription, and translation of genetic information as RNA and DNA. Purines are required by all cells for growth and survival and also play a role in signal transduction and translation. Purines and pyrimidines originate primarily from endogenous synthesis, with dietary sources playing only a minor role. The end product of purine metabolism is uric acid (2,6,8-trioxypurine), which must be excreted continuously to avoid toxic accumulation.

 

Disorders of purine and pyrimidine metabolism can involve all organ systems at any age. The diagnosis of the specific disorders of purine and pyrimidine metabolism is based upon the clinical presentation of the patient, determination of specific concentration patterns of purine and pyrimidine metabolites, and confirmatory enzyme assays and/or molecular genetic testing.

 

There are numerous inborn errors of purine and pyrimidine metabolism that have been documented. Clinical features are dependent upon the specific disorder, but represent a broad spectrum of clinical manifestations that may include immunodeficiency, developmental delay, nephropathy, and neurologic involvement. The most commonly described disorder involves a deficiency of hypoxanthine phosphoribosyl transferase (HPRT), the majority of which have classic Lesch-Nyhan syndrome. Lesch-Nyhan syndrome was described in 1964 as the first disorder of purine metabolism. It is an X-linked disorder characterized by severe neurologic impairment, the development of a compulsive self-destructive behavior, and uric acid nephropathy.

Useful For Suggests clinical disorders or settings where the test may be helpful

Evaluating patients with symptoms suspicious for disorders of purine and pyrimidine metabolism

 

Monitoring patients with disorders of purine and pyrimidine metabolism

 

Laboratory evaluation of primary and secondary hyperuricemias

Interpretation Provides information to assist in interpretation of the test results

Abnormal concentrations of measurable compounds will be reported along with an interpretation. The interpretation of an abnormal metabolite pattern includes an overview of the results and of their significance, a correlation to available clinical information, possible differential diagnosis, recommendations for additional biochemical testing and confirmatory studies (enzyme assay, molecular analysis), name, and phone number of contacts who may provide these studies at the Mayo Clinic or elsewhere, and a phone number of the laboratory directors in case the referring physician has additional questions.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Additional confirmatory testing is required for follow-up of abnormal results.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

URACIL

0-2 years: < or =31 mmol/mol creatinine

3-5 years: < or =30 mmol/mol creatinine

6-11 years: < or =28 mmol/mol creatinine

12-17 years: < or =26 mmol/mol creatinine

> or =18 years: < or =35 mmol/mol creatinine

 

URIC ACID

0-2 years: < or =2,249 mmol/mol creatinine

3-5 years: < or =1,900 mmol/mol creatinine

6-11 years: < or =1,398 mmol/mol creatinine

12-17 years: < or =698 mmol/mol creatinine

> or =18 years: < or =669 mmol/mol creatinine

 

HYPOXANTHINE

0-2 years: <53 mmol/mol creatinine

3-5 years: <49 mmol/mol creatinine

6-11 years: <43 mmol/mol creatinine

12-17 years: <36 mmol/mol creatinine

> or =18 years: <40 mmol/mol creatinine

 

XANTHINE

0-2 years: <49 mmol/mol creatinine

3-5 years: <41 mmol/mol creatinine

6-11 years: <30 mmol/mol creatinine

12-17 years: <16 mmol/mol creatinine

> or =18 years: <51 mmol/mol creatinine

Clinical References Provides recommendations for further in-depth reading of a clinical nature

Jurecka A: Inborn errors of purine and pyrimidine metabolism. J Inherit Metab Dis 2009;32:247-263


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