采用 AxSYM 主动 B(12) 分析法测定血清全钴胺素浓度：临床实验室的临界点评估。

Determination of serum holotranscobalamin concentrations with the AxSYM active B(12) assay: cut-off point evaluation in the clinical laboratory.

机构信息

Dipartimento Scienze Mediche, Università degli Studi di Milano, Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Fondazione IRCCS, Milan, Italy.

出版信息

Clin Chem Lab Med. 2010 Feb;48(2):249-53. doi: 10.1515/CCLM.2010.032.

DOI:10.1515/CCLM.2010.032

PMID:19961395

Abstract

BACKGROUND

A reliable early marker is required for diagnosis of cobalamin deficiency. We calculated an appropriate holotranscobalamin (HoloTC) cut-off point for identifying cobalamin deficiency using an immunoenzymatic assay.

METHODS

Determination of the cut-off threshold and correlation between HoloTC and the other diagnostic parameters routinely used for vitamin B(12) deficiency [total vitamin B(12) (tB(12)), folate, homocysteine] were measured in 250 routine blood specimens from 107 men (mean age 59.0+/-18.8 years) and 143 women (mean age 54.2+/-23.1 years). The inclusion criterion was serum tB(12) concentration <or=221 pmol/L.

RESULTS

Analytical performance results agreed with those reported by others. A weak correlation (R=0.42) was found between HoloTC and tB(12). A 40 pmol/L cut-off threshold was chosen for HoloTC and the associated sensitivity and specificity was 0.86 and 0.66, respectively. Out of 250 tested samples, 126 showed tB(12) concentrations 139-221 pmol/L (gray zone, GZ) and 124 had tB(12) concentrations <139 pmol/L (low, L). Values less than the cut-off for HoloTC were present in 68.2% and 37.9% of cases in the GZ and L group, respectively (p<0.01), and in 53.2% of subjects.

CONCLUSIONS

Our results confirmed the analytical reliability of the AxSYM HoloTC assay. The method is adequate for routine use and a cut-off threshold of 40 pmol/L is appropriate for assessing cobalamin deficiency in populations with reduced tB(12) values.

摘要

背景

需要一种可靠的早期标志物来诊断钴胺素缺乏症。我们使用免疫酶分析法计算了适当的全钴胺素（HoloTC）截断值，以确定钴胺素缺乏症。

方法

在 107 名男性（平均年龄 59.0+/-18.8 岁）和 143 名女性（平均年龄 54.2+/-23.1 岁）的 250 例常规血样中测定了 HoloTC 的截断阈值以及与维生素 B12 缺乏症常用的其他诊断参数（总维生素 B12（tB12）、叶酸、同型半胱氨酸）之间的相关性。纳入标准为血清 tB12 浓度<221 pmol/L。

结果

分析性能结果与其他人的报告一致。HoloTC 与 tB12 之间存在弱相关性（R=0.42）。选择 40 pmol/L 作为 HoloTC 的截断值，其灵敏度和特异性分别为 0.86 和 0.66。在 250 个测试样本中，有 126 个样本的 tB12 浓度在 139-221 pmol/L（灰色区域，GZ）之间，124 个样本的 tB12 浓度<139 pmol/L（低，L）。在 GZ 和 L 组中，HoloTC 截断值以下的值分别存在于 68.2%和 37.9%的病例中（p<0.01），53.2%的受试者也存在。