Choi Rihwa, Oh Youngju, Park Mi-Jung, Lee Sang Gon, Lee Eun Hee
Clin Lab. 2021 Apr 1;67(4). doi: 10.7754/Clin.Lab.2020.200714.
Little is known about the reference interval of serum folate concentration if using recently re-standardized assays traceable to the World Health Organization (WHO) international standard reference 03/178 in a Korean population. This study aimed to investigate serum folate levels in Korean subjects without macrocytic anemia or increased homocysteine, for the assessment of folate deficiency.
We retrospectively reviewed data from Korean adults whose hemoglobin, mean corpuscular volume, and serum total homocysteine values were within reference limits.
The median (interquartile range) serum folate level was 7.8 (5.4 - 12.6) ng/mL in men and 10.2 (6.9 - 15.6) ng/mL in women. The reference interval for serum folate (2.5th and 97.5th percentiles) ranged from 2.9 to 38.0 ng/ mL. From among 723 Korean adults, the lower limit of reference intervals of serum folate for folate deficiency, defined as the 2.5th percentile, was 2.9 ng/mL. The prevalence of folate deficiency was higher in men (6.5%) than in women (1.2%, p < 0.05) when a cutoff value of 3.0 ng/mL was applied. Using the cutoff value of 4 ng/mL for folate deficiency, which is in accordance with the instructions from the manufacturer of the new assay and the WHO 2012 guideline for homocysteine as a metabolic indicator before assay standardization, about 5% of subjects were reclassified as folate deficient.
Our study suggests that any change of reference limits using a re-standardized assay needs to be verified in clinical laboratories.
在韩国人群中，若使用最近重新标准化且可溯源至世界卫生组织（WHO）国际标准参考品03/178的检测方法，血清叶酸浓度的参考区间鲜为人知。本研究旨在调查无大细胞性贫血或高同型半胱氨酸血症的韩国受试者的血清叶酸水平，以评估叶酸缺乏情况。
我们回顾性分析了韩国成年人的数据，这些成年人的血红蛋白、平均红细胞体积和血清总同型半胱氨酸值均在参考范围内。
男性血清叶酸水平中位数（四分位间距）为7.8（5.4 - 12.6）ng/mL，女性为10.2（6.9 - 15.6）ng/mL。血清叶酸的参考区间（第2.5和第97.5百分位数）为2.9至38.0 ng/mL。在723名韩国成年人中，定义为第2.5百分位数的血清叶酸参考区间下限为2.9 ng/mL。当应用3.0 ng/mL的临界值时，男性叶酸缺乏患病率（6.5%）高于女性（1.2%，p < 0.05）。按照新检测方法制造商的说明以及WHO 2012年同型半胱氨酸作为检测标准化前代谢指标的指南，使用4 ng/mL作为叶酸缺乏的临界值，约5%的受试者被重新分类为叶酸缺乏。
我们的研究表明，临床实验室需要验证使用重新标准化检测方法时参考限值的任何变化。
