Diagnosis of Inherited Metabolic Disorders by selective metabolite testing: Three years experience at a Tertiary Care Center in Rawalpindi

OBJECTIVE: To determine the pattern of various inherited metabolic disorders specifically through plasma amino acid and urine organic acid testing in high-risk paediatric population.. METHODS: The cross-sectional retrospective study was conducted at the Armed Forces Institute of Pathology, Rawalpindi, Pakistan, and comprised data from April 2015 to March 2018 of children referred to the Department of Chemical Pathology and Endocrinology for work-up of suspected inherited metabolic disorders. Complete clinical history, baseline biochemical investigations, plasma amino acid and urine organic acid profiles, where indicated, were collected. Quantitative plasma amino acid and analysis was carried out by Ion Exchange Chromatography on Biochrome 30+ amino acid analyser, and urine organic acid analysis by Gas Chromatography-Mass Spectrometry. Findings were linked to the identified disorders. SPSS 21 was used for data analysis. RESULTS: Of the 805 cases reviewed, 49(6%) had an inherited metabolic disorder. Male:Female ratio of the cases was 1.5:1, and the median age was 240 days (interquartile range: 1-15695 days). The most common presenting symptom was seizures 316(39.3%) followed by lethargy 283(35.2%). Of the diagnosed cases, aminoacidopathies were 28(57%) and in them, non-ketotic hyperglycaemia accounted for 7(25%.). There were 12(24.5%) cases of organic acidurias followed by 9(18.4%) that were other than the two diagnoses. CONCLUSIONS: The cases of inherited metabolic disorder detected indicated significant prevalence. Non-ketotic hyperglycinemia was the commonest disorder diagnosed.