Newborns screened positive for Galactosemia through Expanded Newborn Screening (ENBS) with borderline levels undergo lactose challenge that requires interruption of breastfeeding temporarily then shifting to soy-based formula.

To determine the percentage of Classical Galactosemia (CGal), Non-classical Galactosemia (NCGal), probable mild variant form, and negative Galactosemia among newborns screened positive for Galactosemia who underwent lactose challenge.

This is a retrospective study. NBS records were reviewed and data were collected from January 2015 to December 2020.

Out of the 117 newborns screened positive for Galactosemia, 58 underwent lactose challenge. Majority were male, term with a birth weight of 2500-4000g and received a final disposition in 4-6 months. Fifteen patients underwent 1-week lactose challenge wherein six reached a resolution on first challenge. Majority, 35 (60.3%) were negative for Galactosemia, six (10.3%) probable mild variant Galactosemia, three (5.2%) NCGal, and no CGal were observed. Fourteen suspected cases (24.1%) are pending final disposition.

This study describes the demographics of newborns flagged for Galactosemia who underwent lactose challenge. A 1-week lactose challenge may be recommended to further detect patients who are negative for Galactosemia.