Harmonizing the Calibrator and Microorganism Used in the Folate Microbiological Assay Increases the Comparability of Serum and Whole-Blood Folate Results in a CDC Round-Robin Study

Details

• Alternative Title:
  J Nutr
• Personal Author:
  Zhang, Ming ; Sternberg, Maya R ; Pfeiffer, Christine M
• Description:
  Background:
  
  Harmonizing critical reagents for the folate microbiological assay (MBA) may improve among-laboratory comparability.
  
  Objective:
  
  We assessed the comparability of the MBA for serum folate (S-FOL) and whole-blood folate (WB-FOL) in an international comparison study.
  
  Methods:
  
  Eight laboratories obtained a kit containing CDC microorganism inoculum (chloramphenicol-resistant Lactobacillus rhamnosus), CDC calibrator (5-methyltetrahydrofolate), and 23 serum and WB hemolysate samples each. Laboratories analyzed the samples in single measurement over 2 d using 4 conditions: in-house microorganism and in-house calibrator (IH-MO & IH-CAL), in-house microorganism and CDC calibrator (IH-MO & CDC-CAL), CDC microorganism and in-house calibrator (CDC-MO & IH-CAL), and CDC microorganism and CDC calibrator (CDC-MO & CDC-CAL). We calculated geometric mean concentrations for each laboratory and condition and compared data to the CDC MBA (target).
  
  Results:
  
  The among-laboratory arithmetic mean S-FOL concentrations for the 4 conditions were 30.2, 28.1, 30.0, and 29.9 (group1, 5-methyltetrahydrofolate IH-CAL) compared with 35.3, 33.3, 33.6, and 30.7 nmol/L (group 2, folic acid IH-CAL), respectively; and 428, 405, 398, and 393 (group 1) compared with 469, 423, 477, and 418 nmol/L (group 2), respectively, for WB-FOL. Differences to the CDC MBA target values were smaller for group 1 (range across conditions; S-FOL: 9.9–21%; WB-FOL: 9.0–18%) compared with group 2 laboratories (S-FOL: 13–30%; WB-FOL: 16–32%) and smaller when CDC reagents were used compared with in-house reagents (S-FOL: 12% compared with 22%; WB-FOL: 13% compared with 25%). A linear mixed model estimated a small microorganism effect (S-FOL: 2.3%; WB-FOL: 2.3%) and a larger mean calibrator effect; folic acid compared with 5-methyltetrahydrofolate calibrator produced 12% higher S-FOL and 15% higher WB-FOL results. When laboratories used CDC reagents, the estimated among-laboratory variability was ~10% for S-FOL and WB-FOL.
  
  Conclusion:
  
  Harmonizing the calibrator and microorganism for the folate MBA has the potential to improve the among-laboratory comparability in future surveys.
  
  
• Subjects:
  Biological Assay Centers For Disease Control And Prevention, U.S. Chromatography, High Pressure Liquid Folic Acid Humans Lacticaseibacillus Rhamnosus Tandem Mass Spectrometry Tetrahydrofolates United States
• Keywords:
  5-methyltetrahytrofolate Folic Acid Lactobacillus Rhamnosus
• Source:
  J Nutr. 148(5):807-817
• Pubmed ID:
  30053280
• Pubmed Central ID:
  PMC8479687
• Document Type:
  Journal Article
• Funding:
  CC999999/ImCDC/Intramural CDC HHSUnited States/
• Volume:
  148
• Issue:
  5
• Collection(s):
  CDC Public Access
• Main Document Checksum:
  urn:sha-512:0aff0f9e8df0dd2eb441a6ea700de752278007993c105b9dfe79f70b96144501c7fa2d88c6b3945d332b14cca6acddb82d3c826759cbdfda5088dd963af7e3d8
• Download URL:
  https://stacks.cdc.gov/view/cdc/110317/cdc_110317_DS1.pdf
• File Type:
  [PDF - 1.13 MB ]