Phenylketonuria is an inherited metabolic disease that can be treated if detected early and can easily be screened with phenylalanine as a biomarker. Phenylketonuria is included in the National Neonatal Screening Program. We aimed to investigate the possible effects of the pandemic on phenylketonuria screening in our country during coronavirus disease 2019 (COVID-19) era. We retrospectively evaluated patients who were referred to our center due to elevated blood phenylalanine levels detected by national screening program retrospective- and prospectively within one-year as of 11 March 2020, the date when first COVID-19 case was detected in our country. Multivariate analysis showed birth region and phenylalanine levels to be independently associated with the time period until the first admission to hospital, but none of the parameters were significantly associated with the pandemic. There was no evidence that the COVID-19 pandemic affected the screening of newborn phenylketonuria, however since the data was limited to our center and to draw generalized conclusions larger scaled multicentric studies are needed.

Keywords: national newborn screening, pandemic, hyperphenylalaninemia