Dean B, Kolavcic M S, Wark J D, Harrison L C
Endocrine Laboratory, Royal Melbourne Hospital, Parkville, Victoria, Australia.
Clin Chim Acta. 1988 Aug 31;176(2):169-78. doi: 10.1016/0009-8981(88)90204-5.
Using a commercial kit method we obtained a vitamin D metabolite level within the normal range in a patient with biopsy-proven osteomalacia. This suggested that the ethanol extraction method employed had not removed serum factors known to falsely elevate the measurement of vitamin D metabolites. We therefore compared the levels measured after ethanol extraction and after purification by chromatography on Sep-pak C18 or Sephadex LH-20. Vitamin D metabolite levels after ethanol extraction of sera correlated with, but were higher than, those after chromatography on Sep-pak C18 cartridges (r = 0.84; 134 +/- 76 vs 76 +/- 46 nmol/l: mean +/- SD; p less than 0.01). Results were similar after chromatography on Sep-pak C18 and Sephadex LH-20 (r = 0.95; 79 +/- 46 vs 68 +/- 41 nmol/l). Sera from 5 patients (4 with osteomalacia, 1 with chronic pancreatitis/malabsorption) had vitamin D metabolite levels in the normal range after ethanol extraction but had low levels after Sep-pak C18 chromatography; four of these sera also had low levels after chromatography on Sephadex LH-20. These findings indicate that chromatography of serum on Sep-pak C18 cartridges corrects falsely elevated vitamin D metabolite levels measured by protein binding assay.
我们采用一种商业试剂盒方法，在一名经活检证实为骨软化症的患者体内测得维生素D代谢物水平处于正常范围内。这表明所采用的乙醇提取方法并未去除那些已知会导致维生素D代谢物测量值假性升高的血清因子。因此，我们比较了血清经乙醇提取后以及经Sep-pak C18或Sephadex LH-20柱色谱纯化后的测量水平。血清经乙醇提取后的维生素D代谢物水平与经Sep-pak C18柱色谱后的水平相关，但前者更高（r = 0.84；134±76对比76±46 nmol/L：均值±标准差；p<0.01）。经Sep-pak C18和Sephadex LH-20柱色谱后的结果相似（r = 0.95；79±46对比68±41 nmol/L）。5名患者（4名骨软化症患者，1名慢性胰腺炎/吸收不良患者）的血清经乙醇提取后维生素D代谢物水平处于正常范围，但经Sep-pak C18柱色谱后水平较低；其中4份血清经Sephadex LH-20柱色谱后水平也较低。这些发现表明，血清经Sep-pak C18柱色谱可校正通过蛋白质结合测定法测得的假性升高的维生素D代谢物水平。
