RESUMEN
@#Homocystineimia is an Inborn Errors of Metabolism (IEM) which can occur due to accumulation of homocysteine. Homocysteine is one of the sulfur-containing amino acid with thiol group that is formed by demethylation of methionine. Deficiency of enzymes involves in homocysteine metabolism can give rise to seven types of homocystinemia subject to total homocysteine level. Therefore reference ranges are needed to differentiate between normal and abnormal population as well as the type of homocystineimia depending on the enzymes defect in the pathway. Hence, homocysteine reference ranges in children for the Malaysian population were postulated. 3 mL of blood was collected from 86 normal individuals (52 boys and 34 girls) and then subsequently processed and analysed using High Performance Liquid Chromatogrphy – Ion Exchange Chromatography (HPLC-IEC). The calculated mean total homocysteine for the population was 8.1 ± 3.89 µM (95% confidence interval, l 7.3-8.9 µM). Reference range was 2.5 – 16.2 µM with lower and upper cut-off were 1.0 µM dan 21.0 µM, respectively. The newly developed reference range of total homocysteine for Malaysian children is able to reduce false negative cases in the laboratory.