The establishment of LC-MS/MS assays-specific reference intervals for serum folates and its application in evaluating FA-supplemented folate deficiency patients: Appeals for a suitable and individualized supplementation

• Published in: Clinica chimica acta Vol. 537; pp. 96 - 104
• Main Authors: Liu, Zhenni, Jin, Lizi, Zhang, Jiangtao, Zhou, Weiyan, Zeng, Jie, Zhang, Tianjiao, Zhang, Chuanbao
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2022
• Subjects: Folate deficiency; Folic acid; Fortification; Liquid chromatography-tandem mass spectrometry; Neural tube defects; Reference interval; Liquid chromatography-tandem mass spectrometry; Reference interval; Fortification; Neural tube defects; Folate deficiency; Folic acid
• ISSN: 0009-8981; 1873-3492; 1873-3492
• DOI: 10.1016/j.cca.2022.09.019

•LC-MS/MS assay-specific RIs were established for serum folates vitamers.•The potential over-usage of FA supplements was observed in folates deficiency patients.•The LC-MS/MS assay-specific folates RIs for the evaluation of individual nutrition conditions and over-dosage monitoring were recommended. Little known about folates status in folate deficiency patients. This study aims to establish liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay-specific reference intervals (RIs) for serum 5-Methyltetrahydrofolate (5MeTHF), folic acid (FA), 5-Formyltetrahydrofolate (5FoTHF), and total folate (TFOL), and investigate the folates status in FA-supplemented folate deficient patients. Sera from 120 reference subjects were selected and measured. An LC-MS/MS method for serum 5MeTHF, FA, and 5FoTHF was employed. RIs were derived based on the CLSI C28-A3. Serum folate levels of 38 FA-supplemented folate deficiency patients were analyzed. RIs (median) for 5MeTHF, FA, 5FoTHF, and TFOL were 3.83–62.33 nmol/L (12.27 nmol/L), 0.30–0.92 nmol/L (0.49 nmol/L), <0.73 nmol/L (0.00 nmol/L), and 4.17–63.47 nmol/L (12.66 nmol/L), respectively. Approximately 53 % (20/38), 74 % (28/38), and 63 % (24/38) of patients presented high levels of 5MeTHF, FA, and TFOL, respectively, which far exceeded the upper reference limit (URL) of the corresponding RIs. A half (18/38) of patients showed simultaneously higher 5MeTHF and FA levels which were beyond the URLs of RIs. Near one-third (11/38) of patients exhibited extremely high FA levels which exceeded the 100-fold URL of RIs. The highest levels can be 539 nmol/L for FA, 364 nmol/L for 5MeTHF, and 686 nmol/L for TFOL. LC-MS/MS assay-specific RIs were established for folates vitamers without age or gender partitioning. Abnormally high levels of unmetabolized FA and 5MeTHF were observed in quite a few FA-supplemented patients. Considering the adverse risks caused by folates excess, we appeal for a justifiable and individualized FA supplementation. We also recommend establishing LC-MS/MS assay-specific RIs for routine monitoring of folates status.