A. Panzeri

D. Szoke

M. Panteghini

S. Borille

S. Ferraro

AIR Universita degli studi di Milano

S1079
Patient sample management, (standardization, harmonization,reference ranges, etc)
Cod: W275
REFERENCE INTERVAL FOR SERUM FOLATE MEASURED WITH AN ASSAY TRACEABLE TO THE WHO
INTERNATIONAL STANDARD
S. Ferraro 1, A. Panzeri 2, S. Borille 1, D. Szoke 1, M. Panteghini 2
1Clinical Pathology Unit, ‘Luigi Sacco’ University Hospital, ASST Fatebenefratelli-Sacco, Milan, Italy
2Research Centre for Metrological Traceability in Laboratory Medicine (CIRME), University of Milan, Milan, Italy
(Italy)
elena.aloisio@unimi.it
BACKGROUND: Most folate immunoassays have been recently recalibrated to the WHO International Standard-NIBSC
03/178 to improve inter-assay harmonization. However, we observed that the recalibration of Roche Diagnostics Folate III
assay yielded a significant shift in the average folate measured values, with a 50% difference vs. the old Roche assay at
concentrations around the lower reference limit (LRL). Here we report data from apparently healthy individuals obtained
with the WHO-recalibrated assay for defining the traceable reference interval for serum folate.
METHODS: We enrolled 322 healthy blood donors (50% males; median age, 45.5 years) with haemoglobin and erythrocyte
MCV values within reference limits and not undertaking folic acid supplementation. Serum samples were measured by
using WHO-recalibrated Roche Folate III assay (code 07559992190) on a Cobas 6000 analyzer (CV≤7.2% and limit of
detection of 0.6 µg/L). Reference interval derivation was according to CLSI C28-A3c standard. Multiple regression models
were used to estimate the influence of age, gender, Italian origin, smoking habit and portions of consumed fruit/vegetables
on folate concentrations.
RESULTS: We found no gender-related difference. Folate median (25-75th percentile) concentrations were 4.1 (2.9-5.6) µg/
L. The estimated reference interval [2.5-97.5th percentile limits (90%CI)] was 1.3 (1.1-1.4) - 9.8 (8.6-12.2) µg/L. Notably,
the LRL was markedly lower than the one (3.3 µg/L) previously estimated by us using the old Roche assay on a similar
population. Folate values significantly (P<0.001) increased with age and with the number of taken portions of fruit/
vegetables per day (adjusted R2, 18.9%), with no influence by smoking and non–Italian origin.
CONCLUSIONS: Our experimental estimate of LRL using Roche WHO traceable assay on a population free of folate
supplementation reveals that this value is far lower than that reported by the manufacturer in the assay package insert (3.9
µg/L), likely including fortified subjects. Laboratories using folate assays harmonized to NIBSC 03/178 material may adopt
the LRL of 1.3 µg/L to detect vitamin deficiency, providing that there are no differences in test results across populations
due to biological or environmental factors.
Poster Abstracts – EuroMedLab Athens 2017 – Athens, 11-15 June 2017 • DOI 10.1515/cclm-2017-5031
Clin Chem Lab Med 2017; 55, Special Suppl, pp S1 – S1121, June 2017 • Copyright © by Walter de Gruyter • Berlin • Boston
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Reference interval for serum folate measured with an assay traceable to the WHO international standard

https://air.unimi.it/retrieve/handle/2434/504422/904067/EuroMedLab_PanteghiniEtAlii_ReferenceInterval_2017.pdf

Reference interval for serum folate measured with an assay traceable to the WHO international standard

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