Refsum Helga, Johnston Carole, Guttormsen Anne Berit, Nexo Ebba
Oxford Centre for Gene Function, Laboratory of Physiology, Department of Pharmacology, University of Oxford, Oxford, United Kingdom.
Clin Chem. 2006 Jan;52(1):129-37. doi: 10.1373/clinchem.2005.054619. Epub 2005 Oct 20.
We developed microbiological assays (MBAs) to identify determinants and to establish reference values for cobalamin bound to transcobalamin [holotranscobalamin (holoTC)] and total TC in plasma.
We captured holoTC with magnetic beads with TC antibodies and used a conventional MBA for cobalamin measurements. Total TC was determined as holoTC after TC was saturated with cyanocobalamin. The new assays were compared with published methods. Determinants and reference values were determined in 500 blood donors, ages 18-69 years.
Determination of cobalamin, holoTC, and TC by MBA required <150 microL. HoloTC and TC by MBA correlated with holoTC by RIA (r = 0.95) and TC by ELISA (r = 0.79), respectively. Between-day CVs for holoTC and total TC were 4%-9%. Women had lower holoTC than men, but only at age < or = 45 years. In multivariate regression analyses, holoTC was positively associated with age (in women only), creatinine (in men only), and plasma concentrations of total TC, folate, and cysteine, but inversely correlated with homocysteine and methylmalonic acid. For all study participants, total TC was associated with holoTC and number of TCN2 766C alleles; in female participants only, total TC was also associated with age, homocysteine, and cysteine. Reference values were 670-1270 pmol/L for TC and 42-157 pmol/L for holoTC, but they differed according to age and sex.
Our MBAs for TC and holoTC required low plasma volume and performed acceptably compared with other methods. Determinants of holoTC and TC differed between men and women and according to age. Separate reference intervals for holoTC should be considered in younger women.
我们开发了微生物学检测方法（MBAs），以确定血浆中与转钴胺素结合的钴胺素[全转钴胺素（holoTC）]和总转钴胺素（TC）的决定因素并建立参考值。
我们用带有TC抗体的磁珠捕获holoTC，并使用传统的MBAs进行钴胺素测量。用氰钴胺使TC饱和后，将总TC测定为holoTC。将新检测方法与已发表的方法进行比较。在500名年龄在18至69岁的献血者中确定决定因素和参考值。
用MBAs测定钴胺素、holoTC和TC所需血浆量<150微升。MBAs检测的holoTC和TC分别与放射免疫分析法（RIA）检测的holoTC（r = 0.95）和酶联免疫吸附测定法（ELISA）检测的TC（r = 0.79）相关。holoTC和总TC的日间变异系数为4%-9%。女性的holoTC低于男性，但仅在年龄≤45岁时。在多变量回归分析中，holoTC与年龄（仅在女性中）、肌酐（仅在男性中）以及总TC、叶酸和半胱氨酸的血浆浓度呈正相关，但与同型半胱氨酸和甲基丙二酸呈负相关。对于所有研究参与者，总TC与holoTC和TCN2 766C等位基因数量相关；仅在女性参与者中，总TC还与年龄、同型半胱氨酸和半胱氨酸相关。TC参考值为670-1270 pmol/L，holoTC参考值为42-157 pmol/L，但它们因年龄和性别而异。
我们用于TC和holoTC的MBAs所需血浆量少，与其他方法相比表现良好。holoTC和TC的决定因素在男性和女性之间以及因年龄而异。对于年轻女性，应考虑单独的holoTC参考区间。
