Comparison of Tandem Mass Spectrometry and the Fluorometric Method—Parallel Phenylalanine Measurement on a Large Fresh Sample Series and Implications for Newborn Screening for Phenylketonuria

Phenylketonuria (PKU) was the first disease to be identified by the newborn screening (NBS) program. Currently, there are various methods for determining phenylalanine (Phe) values, with tandem mass spectrometry (MS/MS) being the most widely used method worldwide. We aimed to compare the MS/MS method with the fluorometric method (FM) for measuring Phe in the dried blood spot (DBS) and the efficacy of both methods in the NBS program. The FM was performed using a neonatal phenylalanine kit and a VICTOR2TM D fluorometer. The MS/MS method was performed using a NeoBaseTM 2 kit and a Waters Xevo TQD mass spectrometer. The Phe values measured with the MS/MS method were compared to those determined by the FM. The cut-off value for the NBS program was set at 120 µmol/L for FM and 85 µmol/L for MS/MS. We analyzed 54,934 DBS. The measured Phe values varied from 12 to 664 µmol/L, with a median of 46 µmol/L for the MS/MS method and from 10 to 710 µmol/L, with a median of 70 µmol/L for the FM. The Bland–Altman analysis indicated a bias of −38.9% (−23.61 µmol/L) with an SD of 21.3% (13.89 µmol/L) when comparing the MS/MS method to the FM. The Phe value exceeded the cut-off in 187 samples measured with FM and 112 samples measured with MS/MS. The FM had 181 false positives, while the MS/MS method had 106 false positives. Our study showed that the MS/MS method gives lower results compared to the FM. Despite that, none of the true positives would be missed, and the number of false-positive results would be significantly lower compared to the FM

Global impact of COVID-19 on newborn screening programmes

Introduction The global COVID-19 pandemic has presented extraordinary disruption to healthcare services and exposed them to numerous challenges. Newborn screening (NBS) programmes were also affected; however, scarce data exist on the impact of COVID-19 on NBS. Methods We conducted an international survey to assess the global impact of COVID-19 on NBS, with the main aim of gathering the experiences of the COVID-19 pandemic from a large and representative number of NBS centres worldwide. Results The results of our study showed that COVID-19 impacted the NBS programmes, at least partially, in 29 out of 38 responding countries. Majority of the screening centres experienced a broad spectrum of difficulties and most were affected more in the second wave of the pandemic. Delays and unreliability with the postal service as well as flight cancellations caused delays in samples arriving to screening centres and with the provision of laboratory equipment and reagents. The availability of laboratory staff was sometimes reduced due to infection, quarantine or reassignment within the healthcare facility. Sample collection at home, second-tier tests and follow-up were also affected. Social restrictions and interruptions in public transport added to these difficulties. Only a limited number of centres managed to retain a fully functioning NBS programme. Conclusion As the pandemic might continue or could recur in future years, it would be useful to develop guidelines to protect these valuable services