Reduction in newborn screening metabolic false-positive results following a new collection protocol

PurposeNewborn screening includes testing for many metabolic diseases. False-positive results are higher among neonatal intensive care unit infants, resulting in increased confirmatory testing and family stress. Amino acid administration as a component of total parenteral nutrition is commonly used in the neonatal intensive care unit and suggested as a factor increasing false-positive results. The purpose of this study was to investigate the impact of a new sample collection protocol on false-positive results.MethodsThis was a 2-year retrospective cohort study. Infants were grouped by birth year into pre- and postprotocol implementation and stratified by birth weight category. In 2010, newborn screening samples were collected from all infants regardless of total parenteral nutrition administration. In 2011, the protocol was changed, and total parenteral nutrition was replaced with 10% dextrose in water (D10W) for 3 h before sample collection.ResultsData from 539 neonatal intensive care unit admissions were reviewed. The new protocol reduced false-positive results for each birth weight group by at least 50% and overall by 74% (P = 0.008). The odds of having a false-positive result preintervention were 3.87 times higher than postintervention. The protocol reduced estimated costs by >80%.ConclusionA protocol interrupting total parenteral nutrition for 3 h before newborn screening collection resulted in a 74% reduction in false-positive results in a neonatal intensive care unit.Genet Med16 6, 477–483.