A TMS is an analytic instrument that separates and determines the quantity of ions in a sample on the basis of their mass-to-charge ratios. Many disorders including amino acidopathies, organic acidurias, urea cycle defects and fatty oxidation defects can be detected by TMS. These were not included in the past screening programmes in Singapore. Previously, newborn screenings were done only for G6PD deficiency, congenital hypothyroidism and hearing impairment.

The metabolic screen is performed between the second and fifth postnatal day, when the baby has established full oral feeds with breast milk or a formula. Three to four drops of blood are obtained by heel prick onto a special filter paper. This blood-spot card is dried in room air and sent to the National Expanded Newborn Screening Laboratory located at KK Women’s and Children’s Hospital. The results of the screening test are available after two working days.

The metabolic screen test using TMS has a high predictive value with a sensitivity of 96%, specificity 99.8% and recall rate 1.5 - 2%. Patients with grossly abnormal screening tests are referred to metabolic specialists for further management. Those with borderline abnormal results are recalled for a repeat screening test.

The patients who are confirmed to have IEMs are managed at 2 centres in Singapore. One at NUH, is headed by A/Prof Denise Goh, a paedatrician and board-certified metabolic geneticist. The other, at KKH, by Associate Consultant Dr Tan Ee Shien and Visiting Consultant Dr Teo Siak Hong. The treatment of the IEM depends on the type of the metabolic abnormality. Disorders of amino acid are managed by dietary restriction of the amino acids that the body cannot break down; for example, restriction of Phenylalanine in Phenylketonuria (PKU) and Leucine, Isolucine and Valine in Maple Syrup Urine Disease (MSUD). Organic acidurias are treated by dietary restriction of amino acids and oral carnitine supplementation. Ureas cycle disorders are treated with proteinrestricted diet, sodium benzoate and arginine supplementation.

The screening programme was launched in public hospitals in July 2006 and in the private hospitals in October 2006. Out of the 18,000 babies screened, 4 cases of IEMs have been detected, giving an incidence of one in 4,500. The IEM cases detected were Maternal Carnitine Uptake Defect, Medium Chain AcylCoA Dehydrogenase Deficiency (MCAD), Glutaric Aciduria Type 1 and Methylmalonic Acidemia. The four infants were managed optimally before the occurrence of metabolic crisis and life threatening complications were prevented. TMS is also used to monitor patients who have IEMs on treatment for conditions such as Phenylketonuria, organic acidurias and primary carnitine deficiency.

"Many of these conditions, if undiagnosed or untreated, can result in early death or permanent neurodevelopmental sequelae. The metabolic screen identifies babies who may have IEMs, often before they develop symptoms of the disease. Early diagnosis and appropriate treatment can reduce the risk of death and developmental delay in majority of the cases," said Clinical A/Prof Samuel Rajadurai, Head, Dept of Neonatology, KKH and Programme Director of the National Expanded Newborn Screening Programme.


Clin A/Prof Samuel Rajadurai, Head, Department of Neonatology, KKH and Programme Director of the National Expanded Newborn Screening Programme checks a newborn in the hospital's Neonatal Intensive Care Unit.

Clinical A/Prof Samuel Rajadurai is the Programme Director and A/Prof Denise Goh from NUS and Consultant, Dept of Paediatrics, NUH is the Co-Programme Director. A/Prof Denise Goh who is a Paediatric Geneticist and a Metabolic Specialist is also a Visiting Consultant to KKH. Dr Tan Ee Shien, Associate Consultant, Medical Technologists (Ms Sherry Poh and Ms Yeo Shu Jun) and Principal Scientific Officer Ms Clare Hart and Laboratory Manager Ms Lee So Chow are the other dedicated team members of the Expanded Newborn Screening Programme.