Two international Round Robin studies showed good comparability of 5-methyltetrahydrofolate, but poor comparability of folic acid measured in serum by different HPLC-MS/MS methods

Details

• Alternative Title:
  J Nutr
• Personal Author:
  Fazili, Zia ; Sternberg, Maya R. ; Paladugula, Neelima ; Pfeiffer, Christine M.
• Description:
  Background
  
  Serum folate methods produce different results. The comparability of HPLC-MS/MS methods is not well-documented.
  
  Objective
  
  We conducted an international “Round Robin” investigation to assess the comparability, precision, and accuracy of serum folate HPLC-MS/MS methods.
  
  Design
  
  The CDC laboratory, 7 laboratories with independently-developed methods (group 1), and 6 laboratories with an adapted CDC method (group 2) analyzed folate forms in 6 serum pools and 6 calibrators from CDC (duplicate analysis over 2 days) and in 2 three-level reference materials (duplicate analysis).
  
  Results
  
  All laboratories measured 5-methyltetrahydrofolate (5-methylTHF) and folic acid; some measured additional folate forms. Geometric mean concentrations (nmol/L) for 5-methylTHF in the 6 serum pools were 18.3 (CDC), 13.8–28.9 (group 1), and 16.8–18.6 (group 2); for folic acid, 3.42 (CDC), 1.09–4.74 (group 1), and 1.74–2.90 (group 2). The median imprecision (CV) for 5-methylTHF was 4.1% (CDC), 4.6%–11% (group 1), and 1.7%–6.0% (group 2); for folic acid, 6.9% (CDC), 4.9%–20% (group 1), and 3.9%–23% (group 2). The mean (SD; range) recovery of 5-methylTHF spiked into serum was 98% (27%; 59%–138%) for group 1 and 98% (10%; 82%–111%) for group 2; for folic acid, 93% (29%; 67%–198%) for group 1 and 81% (16%; 64%–102%) for group 2. The mean relative bias for 5-methylTHF compared to the reference material certificate value was 12% (CDC), -24% to 30% (group 1), and -0.6% to 16% (group 2); for folic acid, 73% (CDC), -47% to 578% (group 1), and -3.3% to 67% (group 2).
  
  Conclusions
  
  For 5-methylTHF, group 2 laboratories demonstrated better agreement and precision, less variable spiking recovery, and less bias using a reference material. Laboratory performance for folic acid was highly variable and needs improvement. Certified reference materials for serum folate forms and total folate are needed to improve method accuracy.
  
  
• Subjects:
  Calibration Chromatography, High Pressure Liquid Folic Acid Humans Laboratories Nutritional Status Reference Values Tandem Mass Spectrometry Tetrahydrofolates
• Keywords:
  5,10-methenyltetrahydrofolate 5-formyltetrahydrofolate MeFox Tetrahydrofolate
• Source:
  J Nutr. 147(9):1815-1825
• Pubmed ID:
  28768831
• Pubmed Central ID:
  PMC5712443
• Document Type:
  Journal Article
• Funding:
  CC999999/Intramural CDC HHSUnited States/
• Volume:
  147
• Issue:
  9
• Collection(s):
  CDC Public Access
• Main Document Checksum:
  urn:sha256:0a027903b4c950762629d7f51a22abe924e2dd7d60213aca0b8b33fc69983daa
• Download URL:
  https://stacks.cdc.gov/view/cdc/50457/cdc_50457_DS1.pdf
• File Type:
  [PDF - 533.48 KB ]