Related Experiment Videos
Allopurinol challenge test in children
A B Burlina1, V Ferrari, C Dionisi-Vici
1Department of Pediatrics, University of Padua, Italy.
Insights
The allopurinol challenge test established normal urinary orotic acid excretion in children and adolescents. This test also identified elevated orotic acid levels in children with urea-cycle disorders, such as ornithine transcarbamylase deficiency.
Area of Science:
- Biochemistry
- Pediatric Medicine
- Metabolic Disorders
Background:
- Establishing reference ranges for urinary orotic acid is crucial for diagnosing metabolic disorders in pediatric populations.
- The allopurinol challenge test is a diagnostic tool used to assess purine metabolism and detect certain enzyme deficiencies.
Purpose of the Study:
- To determine normal urinary orotic acid excretion levels in healthy children and adolescents following an allopurinol challenge.
- To evaluate the utility of the allopurinol challenge test in identifying urea-cycle disorders, specifically ornithine transcarbamylase deficiency.
Main Methods:
- A single oral dose of allopurinol (100-300 mg based on age) was administered to 44 healthy pediatric subjects (6 months to 17 years).
- Urinary orotic acid levels were measured and normalized to creatinine to establish peak excretion values across different age groups.
- The test was also conducted on six children with known urea-cycle disorders, including five with ornithine transcarbamylase deficiency.
Main Results:
- Peak urinary orotic acid levels in healthy children and adolescents ranged from 9.3 to 13.0 mumol/mmol creatinine across age groups.
- The mean peak orotic acid level in all healthy children tested was 3.1 +/- 2.7 mumol/mmol creatinine.
- Children with urea-cycle disorders, particularly ornithine transcarbamylase deficiency, showed significantly elevated urinary orotic acid levels (26-134 mumol/mmol creatinine) after allopurinol administration.
Conclusions:
- The allopurinol challenge test provides valuable reference ranges for urinary orotic acid excretion in pediatric populations.
- This test is effective in detecting elevated orotic acid levels indicative of urea-cycle disorders, aiding in their diagnosis.
Abstract:
The allopurinol challenge test was performed on 44 healthy subjects (28 children and 16 adolescents) in order to establish normal values of urinary orotic acid excretion following allopurinol ingestion in the paediatric population. The subjects were divided into three groups according to their age: 6 months to 6 years; 6 years to 10 years; and 10 years to 17 years. They were given 100 mg, 200 mg, or 300 mg of allopurinol, respectively (based on age) in a single oral dose. Maximum peak urinary orotic acid levels following ingestion of allopurinol were 13.0 (n = 14), 9.3 (n = 14), and 10.2 (n = 16) mumol/mmol creatinine in the three groups, respectively. In all children tested the peak orotic acid level was 3.1 +/- 2.7 mumol/mmol creatinine (mean +/- SD, n = 44). This allopurinol challenge test was also performed in six children with urea-cycle disorders, including five females with ornithine transcarbamylase (OTC) deficiency, all of whom demonstrated abnormally elevated levels of urinary orotic acid (peak levels of 26-134 mumol/mmol creatinine) following allopurinol ingestion.