Stopping Parenteral Nutrition for 3 Hours Reduces False Positives in Newborn Screening

ObjectiveTo evaluate effects of holding parenteral nutrition (PN) for 3 hours prior to newborn screening (NBS) on false-positive NBS rate for amino acids (AAs) in very low birth weight (VLBW) infants (birth weight <1500 g).Study designWe analyzed data from 12 567 consecutive births in 1 hospital between May 2010 and June 2013. VLBW infants were stratified into 3 groups: (1) infants without PN before NBS (no-PN group); (2) infants with early PN running at the time of NBS (early-PN group); and (3) infants with early-PN that were temporarily replaced by dextrose-containing intravenous fluid 3 hours prior to NBS (stop-PN group). We compared the false-positive rate for AA and cost effectiveness between the groups.ResultsThe false-positive rate for AA among 413 VLBW infants was significantly higher than infants with birth weight >1500 g (7.62% vs 0.05%; P < .001). There were no false-positive results for AA in the no-PN group. The false-positive rate for AA in the stop-PN group (2/65) was significantly lower than the early-PN group (29/245) (3.1% vs 11.8%; P = .037). The stop-PN group was more cost effective than early-PN group, saving $17.27 per infant screened ($5.53 vs $22.80) or $192.54 for each false-positive result for AA averted. Further reductions in inconclusive samples were also noted.ConclusionsVLBW and early-PN are significant factors for false-positive results for AA. Holding PN containing AAs for 3 hours before NBS collection is a practical and cost-effective method to significantly reduce the false-positive rate for AA in VLBW infants.