Establishment of Reference Ranges and Profile of Urinary Organic Acids in Different Pediatric Age Groups of the Iranian Healthy Population



Dadkhah A¹ ; Hashemipour M² ; Fassihi A³ ; Bahara B⁴ ; Pourfarzam M¹ Show Affiliations
Source: Journal of Isfahan Medical School Published:2014

Abstract

Background: Organic acidurias are a heterogenous group of inherited metabolic disorders characterized by the accumulation and urinary excretion of organic acids. Delay in the detection and treatment of many of these disorders may lead to permanent brain damage or death. Accurate and early diagnosis is therefore paramount. The diagnosis of these disorders is achieved by the analysis of organic acids in the urine using gas chromatography/mass spectrometry (GC/MS). Since genetic and environmental factors and feeding habits can affect the concentration and profile of organic acids, for each population, data should be collected appropriate to that population. Such data did not exist for the Iranian population and thus, needed to be collected. Methods: 140 random urine samples were collected from healthy children in 4 age groups: term neonates (< 30 days), premature neonates, infants (1 month-2 years), and children (> 2 years). In addition, urine samples were collected from 10 children with classical symptoms of inherited metabolic disorders. After extraction and preparation of trimethylsilyl derivatives, organic acids were analyzed using GC/MS. Findings: 61 organic acids in 140 healthy urine samples were measured and the results were reported as the 2.5th-97.5th percentiles. These compounds were normal components of urine and some marker of diseases. In addition, among 10 samples collected from patients suspected of a metabolic disease, 2 patients with methyl malonic academia, 1 patient with propionic acidaemia and 1 patient with glutaric academia type 2 were identified. Conclusion: Urinary organic acid analysis is not currently performed in Iran and samples are sent abroad for investigation. In addition, no reference ranges for urinary organic acids in healthy Iranian children is available. This article, for the first time, reported the urinary organic acid analysis using GC/MS and reference ranges for the Iranian population. Urinary organic acids can now be analysed and results become available within the same day of patient admission in order to initialize early and targeted treatment. This study shows that metabolic disorders do exist in high proportion of patient with clinical signs and it appears that these diseases are prevalent. It also seems that methyl malonic acidemia is the most common disorder in patient with classic symptoms of organic acidemia in Iran.