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

Perko, Daša (author), Grošelj, Urh (author), Čuk, Vanja (author), Remec, Žiga Iztok (author), Žerjav-Tanšek, Mojca (author), Drole Torkar, Ana (author), Krhin, Blaž (author), Biček, Ajda (author), Oblak, Adrijana (author), Battelino, Tadej (author), Repič-Lampret, Barbka (author)

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 VICTOR2$^{TM}$ D fluorometer. The MS/MS method was performed using a NeoBase$^{TM}$ 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.

• Language: English
• Keywords: tandem mass spectrometry, MS/MS, fluorometric method, FM, comparison, phenylalanine, Phe, phenylketonuria, PKU, newborn screening, NBS, false positive results, recall rate
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: MF - Faculty of Medicine
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 11 str.
• Numbering: Vol. 24, iss. 3, art. 2487
• PID: 20.500.12556/RUL-155551
• UDC: 616-053.2
• ISSN on article: 1422-0067
• DOI: 10.3390/ijms24032487
• COBISS.SI-ID: 147446787
• Publication date in RUL: 05.04.2024

Record is a part of a journal

• Title: International journal of molecular sciences
• Shortened title: Int. j. mol. sci.
• Publisher: MDPI
• ISSN: 1422-0067
• COBISS.SI-ID: 2779162

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: tandemska masna spektrometrija, MS/MS, fluorometrična metoda, FM, primerjava, fenilalanin, Phe, fenilketonurija, pregled novorojenčka, PKU, lažno pozitivni rezultati, NBS, stopnja odpoklica

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P3-0343
• Name: Etiologija, zgodnje odkrivanje in zdravljenje bolezni pri otrocih in mladostnikih