[Screening of newborns for inborn errors of metabolism by tandem mass spectrometry].

Tandem mass spectrometry is an analytical method which is being implemented for neonatal screening. The method can determine the content of amino acids and acylcarnitines in neonatal screening samples in one integrated analysis. This allows detection of more than 20 inherited disorders of amino acid, fatty acid and organic acid metabolism. The aggregate incidence of these disorders is in the order of 1:4000. The principal disease which is detectable is medium-chain acyl-CoA dehydrogenase deficiency, which has an incidence of 1:10,000-1:20,000 in Northern Europe. Medium-chain acyl-CoA dehydrogenase deficiency puts the affected at risk of life-threatening metabolic crises, which are preventable if the condition has been diagnosed. Hence, the prognosis is excellent. The central theme for therapeutic management of medium-chain acyl-CoA dehydrogenase deficiency is carbohydrate supplementation, especially in situations of intercurrent illness. Tandem mass spectrometry screening will also enhance the present screening for phenylketonuria which employs a bacterial assay: the screening sample can be obtained 48-72 hours post partum, the false-positive rate will be reduced, and there will be no interference with antibiotics. Tandem mass spectrometry is being used in state-mandated screening panels in a few places and is being tested in pilot studies in many other places. A national prospective pilot project was launched on February 1, 2002 in Denmark. The project includes tandem mass spectrometry screening for galactosemia. In addition to neonatal screening, tandem mass spectrometry can be used for investigation of metabolic diseases, sudden unexpected death of infancy and shaken baby syndrome. Critical appraisal of tandem mass spectrometry will lead to improved health for infants affected by rare inherited disorders of metabolism.