Ueland P M, Refsum H, Stabler S P, Malinow M R, Andersson A, Allen R H
Department of Pharmacology and Toxicology, Armauer Hansens Hus, University of Bergen, Norway.
Clin Chem. 1993 Sep;39(9):1764-79.
Total homocysteine is defined as the sum of all homocysteine species in plasma/serum, including free and protein-bound forms. In the present review, we compare and evaluate several techniques for the determination of total homocysteine. Because these assays include the conversion of all forms into a single species by reduction, the redistribution between free and protein-bound homocysteine through disulfide interchange does not affect the results, and total homocysteine can be measured in stored samples. Total homocysteine in whole blood increases at room temperature because of a continuous production and release of homocysteine from blood cells, but artificial increase is low if the blood sample is centrifuged within 1 h of collection or placed on ice. Different methods correlate well, and values between 5 and 15 mumol/L in fasting subjects are considered normal. Total homocysteine in serum/plasma is increased markedly in patients with cobalamin or folate deficiency, and decreases only when they are treated with the deficient vitamin. Total homocysteine is therefore of value for the diagnosis and follow-up of these deficiency states and may compensate for weaknesses of the traditional laboratory tests. In addition, total homocysteine is an independent risk factor for premature cardiovascular diseases. These disorders justify introduction of the total homocysteine assay in the routine clinical chemistry laboratory.
总同型半胱氨酸定义为血浆/血清中所有同型半胱氨酸种类的总和，包括游离形式和与蛋白质结合的形式。在本综述中，我们比较并评估了几种测定总同型半胱氨酸的技术。由于这些检测方法包括通过还原将所有形式转化为单一物种，通过二硫键交换在游离同型半胱氨酸和与蛋白质结合的同型半胱氨酸之间的重新分布不会影响结果，并且可以在储存的样本中测量总同型半胱氨酸。全血中的总同型半胱氨酸在室温下会增加，因为血细胞会持续产生和释放同型半胱氨酸，但如果血液样本在采集后1小时内离心或置于冰上，人为增加的量会很低。不同方法之间相关性良好，空腹受试者中5至15μmol/L的值被认为是正常的。钴胺素或叶酸缺乏患者的血清/血浆中的总同型半胱氨酸会显著增加，只有在使用缺乏的维生素进行治疗时才会降低。因此，总同型半胱氨酸对于这些缺乏状态的诊断和随访有价值，并且可能弥补传统实验室检测的不足。此外，总同型半胱氨酸是心血管疾病过早发生的独立危险因素。这些疾病证明了在常规临床化学实验室中引入总同型半胱氨酸检测的合理性。
