Effect of hemoglobin variants on routine glycohemoglobin measurements assessed by a mass spectrometric method.
Effect of hemoglobin variants on routine glycohemoglobin measurements assessed by a mass spectrometric method.
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通过质谱方法评估血红蛋白变异对常规糖化血红蛋白测量的影响。
DOI：
10.1093/clinchem/46.10.1689
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发表时间：
2000
影响因子：
9.3
通讯作者：
A. Shimizu
中科院分区：
文献类型：
--
作者：
T. Nakanishi;A. Miyazaki;K. Iguchi;A. Shimizu
对含有血红蛋白（Hb）变异的样品中的糖化血红蛋白（HbA1c）的比较分析表明，不同的测试系统可能会给出不同的结果(1)(2)(3)。对于这类样品，HPLC方法通常低估了HbA1c的真实值，尽管有一些变体给出了HbA1c的阳性误差。如果含有Hb β链的葡萄糖和n端氨基酸的表位发生变化，免疫测定也可能低估该值。因此，需要收集更多关于各种Hb变异对特定HbA1c检测系统的影响的信息(1)。Kobold等人(4)提出的测量HbA1c的参考方法是基于电喷雾电离质谱（ESI/MS）测定Hb β链的n端残基，这些残基是由内源性蛋白酶Glu-C酶切完整的Hb分子释放的。该方法对β链N端糖化Hb的百分比给出了准确的结果，甚至对含有Hb变体的样品也是如此。在本研究中，我们比较了两种商业系统（HPLC和免疫分析）和ESI/MS方法在不同Hb变异样本中测量的HbA1c值。
Comparative analyses of glycohemoglobin (HbA1c) in samples containing hemoglobin (Hb) variants have shown that different test systems may give discrepant results (1)(2)(3). HPLC methods for such samples generally underestimate the true HbA1c value, although a few variants give a positive error for HbA1c. Immunoassays may also underestimate the values if there is a change in an epitope that contains glucose and N-terminal amino acids of the Hb β chains. Therefore, more information needs to be collected on the effects of various Hb variants on specific HbA1c test systems (1). The reference method proposed by Kobold et al. (4) for measuring HbA1c is based on electrospray ionization mass spectrometry (ESI/MS) determination of the N-terminal residues of the Hb β chains, which are released by enzymatic cleavage of the intact Hb molecule with endoproteinase Glu-C. This method gives accurate results for the percentage of glycated Hb at the N terminus of the β chains even for samples containing Hb variants. In the present study, we compared the HbA1c values measured in samples with various Hb variants by two commercial systems (HPLC and immunoassay) and the ESI/MS method.
A total of 81 samples, from nondiabetic and diabetic subjects, were analyzed, of which 45 were homozygous for HbA and 36 were heterozygous for various Hb variants (Table 1⇓ ). The structures of most Hb variants were determined by MS and by DNA analysis, primarily to elucidate the cause of the unexpected values of HbA1c measured by HPLC; one case (HbM Boston) was examined for cyanosis-like symptoms (5). For high-resolution HPLC to measure the content of the variants, we used cation-exchange column chromatography with Polycat A packing and a slow (90 min) gradient buffer change (6). Because HbM was not separated by …