Selective screening for organic acidemias by urine organic acid GC-MS analysis in Brazil: fifteen-year experience.

Background: The gas chromatography/mass spectrometry (GC/MS) method for organic acid analysis was established in developed countries since 1980s, but due to the small number of experienced clinical biochemists in this field and also the short availability of mass spectrometers scarce reports exist on the prevalence of organic acidemias (OAs) in developing countries like Brazil.

Methods: During January 1994 to July 2008, we analyzed organic acids by GC/MS in urine specimens obtained from Brazilian children with clinical suspicion of metabolic diseases.

Results: Two hundred and thirty four cases of disorders of organic acid metabolism, including 218 OAs (3.17%), were diagnosed among 6866 patients investigated. The most frequent disorders were primary lactic acidemia (57), methylmalonic acidemia (34), glutaric acidemia type I (33), propionic acidemia (18), 3-hydroxy-3-methylglutaric aciduria (17), L-2-hydroxyglutaric aciduria (9) and multiple carboxylase deficiency (9). Fourteen cases of mitochondrial fatty acid oxidation disorders, as well as 12 aminoacidopathies and 4 cases of vitamin B12 deficiency were also detected. Prompt treatment following diagnosis led to a better outcome in a considerable number of patients.

Conclusion: Detection of OAs in loco in developing countries is important despite the implied extra costs, since it allows rapid therapy in many cases with a significant reduction of morbidity and mortality and makes the physicians more aware of these pathologies.