The introduction of tandem mass spectrometry technology expands newborn screening and permits early diagnosis of inborn errors of metabolism. Through measurement of a number of acyl carnitines, amino acids and associated ratios, infants at risk of inborn errors of metabolism can be detected. However the increasing availability of the technology places new challenges to areas with established programmes, as well as those without existing newborn screening programmes. Once the technical aspects of tandem mass spectrometry operation are overcome, the initial challenge lies in determination of whether a borderline result is abnormal. Participation in quality assurance and international collaborative programmes is critical to optimise sensitivity and specificity. Some conditions are readily detected, others are more problematic. All positive results must be confirmed with formal testing but the tests required will vary with the disorder. Even after confirmed diagnosis, the significance of the diagnosis for that child may not be clear, as mild forms of disorders, previously thought to be rare, are being recognised by newborn screening programmes. Parents should be provided with easy to understand written information and a management plan. Education of health professionals who may not be familiar with these conditions raises another challenge. Treatment should be supervised by an expert centre and outcome data must be collected to determine the effectiveness of the screening programme in each area.
Humans ; Infant, Newborn ; Neonatal Screening ; organization & administration ; Program Development ; Tandem Mass Spectrometry

Elevated propionyl C3 carnitine is the most common abnormality seen in tandem mass spectrometry newborn screening profiles, with an incidence of 0.15% seen in our South Australian newborn screening programme. The most common cause for this result in our population is vitamin B12 deficiency but differential diagnoses include the inherited disorders of propionic and methylmalonic acid metabolism and cobalamin deficiencies. An approach to confirmatory testing and subsequent management of infants with elevated propionic carnitine is presented.
Humans ; Infant, Newborn ; Metabolism, Inborn Errors ; diagnosis ; Neonatal Screening ; Vitamin B 12 ; metabolism