Diagnosis of metabolic disorders through the analysis of organic acids: the Genetic Department of the University Hospital Ó?Dr. José Eleuterio GonzálezÓ� (UANL) experience

Background: Organic acids (OA) are intermediate metabolism compounds whose analysis allows diagnosing patients with some metabolic disorders.The objective of this study is to present the main indications and diagnoses of the determination of OA in urine in a specialized genetic testing laboratory in northeastern Mexico.Methods: A descriptive, cross-sectional, and retrospective study through a database to analyze the records of samples of patients sent for studies of OA in urine, using gas chromatography-mass spectrometry (GC/MS) from January 2016 to December 2020.Results: Three hundred and thirty-eight samples were received: 83 from school-age children, 70 from infants and pre-schoolers, 35 from patients >18 years old, 34 from patients 11 to 18 years old, 32 from toddlers, 12 from newborns, and two were not specified.The results were 65% normal, 28% abnormal, and 7% inconclusive.A clinical diagnosis was obtained in 62% of the positive cases, coinciding with the clinical suspicion in 64%.The most frequent clinical manifestations were autism spectrum disorders (23.5%), delayed psychomotor development (15%), seizures (11.8%), and intellectual disability (6.8%).In 65.5% of metabolites associated with an inborn error of metabolism (IEMs) were identified, mainly organic acidurias, the most common being 3-methylcrotonyl CoA carboxylase deficiency and methylmalonic acidemia.Bacterial metabolites associated with autism (3-3-hydroxyphenyl-3-hydroxypropionic acid) and vitamin deficiencies were also detected.Conclusions: The determination of OA is useful to corroborate a presumptive diagnosis in patients with unexplained symptoms such as behavioral disorders and intellectual disabilities.However, it is important to have clinical information for a better interpretation of the results.