125I-RIA KIT CANNOT DISTINGUISH VITAMIN-D DEFICIENCY AS WELL AS A MORE SPECIFIC ASSAY FOR 25-HYDROXYVITAMIN-D

被引:12
作者
VIETH, R
CHAN, A
POLLARD, A
机构
[1] UNIV TORONTO,TORONTO,ON M5G 1X5,CANADA
[2] UNIV TORONTO,TORONTO,ON M5G 1X5,CANADA
关键词
RADIOIMMUNOASSAY (RIA); VITAMIN-D; 25-HYDROXYVITAMIN D;
D O I
10.1016/0009-9120(94)00077-9
中图分类号
R446 [实验室诊断]; R-33 [实验医学、医学实验];
学科分类号
1001 ;
摘要
Objectives: To compare a new radioimmunoassay (RIA), measuring vitamin D metabolites, against an established, competitive-protein binding assay (CPBA) that uses rat vitamin D binding protein. Methods: For the CPBA, we first isolated 25-hydroxyvitamin D (25(OH)D) by eluting sample through silica cartridges. For the RIA, serum was added to acetonitrile and centrifuged, followed by RIA using I-125-25(OH)D-3. Results: The within-run CV was 1.5% to 4.1% by RIA, compared to 8.1% to 15.0% by CPBA. For both methods, analytical recovery was not significantly different from 100%, and both methods were appropriately linear with sample dilution. We compared RIA values (y axis) from 90 subjects with 25(OH)D ranging from 11 to 232 nmol/L by CPBA (x axis). The slope was 0.9992 (not significantly different from 1). However, the RIA exhibited a bias of 11.15 nmol/L (p < 0.05 vs 0), and a correlation coefficient of r = 0.923. When the comparison was confined to the 37 samples in the lower half of our reference range, the RIA did not compare well: slope, 0.764 (p < 0.05 vs 1.0); intercept 18.7 nmol/L (p < 0.05 vs 0); r = 0.517. For the samples below 36 nmol/L. by CPBA, there was no discrimination by RIA between the 11 values below, and the 11 above the decision level (25 nmol/L by CPBA) for vitamin 0 deficiency. Conclusions: We conclude that the RIA is not optimized to detect vitamin D deficiency, and for this purpose it is not a valid substitute for conventional 25(OH)D methods.
引用
收藏
页码:175 / 179
页数:5
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