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Endocrinology and Metabolism |
1 Clinical Toxicology Laboratory, University of Wisconsin Hospital and Clinics,2 Department of Pathology,3 Department of Medicine Osteoporosis Clinical Center and Research Program, University of Wisconsin-Madison, and4 Geriatric Research, Education and Clinical Center, William S. Middleton Veterans Affairs Medical Center, Madison, WI.
aAddress correspondence to this author at: University of Wisconsin Hospital and Clinics, Toxicology Laboratory, Room D4/245, 600 Highland Ave., Madison, WI 53792. Fax 608-263-0910; e-mail gl.lensmeyer{at}hosp.wisc.edu.
Background: The concentration of 25-hydroxyvitamin D [25(OH)D] in serum has been designated the functional indicator of vitamin D (VitD) nutritional status. Unfortunately, variability among 25(OH)D assays limits clinician ability to monitor VitD status, supplementation, and toxicity.
Methods: We developed an HPLC method that selectively measures 25-hydroxyvitamin D2 [25(OH)D2] and D3 [25(OH)D3] and compared this assay with a liquid chromatography–tandem mass spectrometry (LC-MS/MS) method, a competitive protein-binding assay (CPBA) on the Nichols AdvantageTM platform, and an RIA from Diasorin.
Results: For the new HPLC assay, between-run CVs were 2.6%–4.9% for 25(OH)D3 and 3.2%–13% for 25(OH)D2; recoveries were 95%–102%; and the assay was linear from 5 µg/L to at least 200 µg/L. Comparison data were as follows: for HPLC vs LC-MS/MS, y = 1.01x – 4.82 µg/L (Sy|x = 4.93 µg/L; r = 0.996) for 25(OH)D3, and y = 0.902x – 0.566 µg/L (Sy|x = 2.56 µg/L; r = 0.9965 for 25(OH)D2; for HPLC vs Diasorin RIA, y = 0.709x – 5.86 µg/L (Sy|x = 7.35 µg/L; r = 0.7509); and for HPLC vs Nichols Advantage CPBA, y = 1.00x – 3.60 µg/L (Sy|x = 32.7 µg/L; r = 0.6823).
Conclusions: The new HPLC method is reliable, robust, and has advantages compared with the Nichols Advantage CPBA and the Diasorin RIA. The Nichols Advantage CPBA overestimated or underestimated 25(OH)D concentrations predicated on the prevailing metabolite present in patients’ sera.
The following articles in journals at HighWire Press have cited this article:
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  A. J. Rovner and K. O. O'Brien Hypovitaminosis D Among Healthy Children in the United States: A Review of the Current Evidence Arch Pediatr Adolesc Med, June 1, 2008; 162(6): 513 - 519. [Abstract] [Full Text] [PDF]
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 N. Binkley, D. Krueger, D. Gemar, and M. K. Drezner Correlation among 25-Hydroxy-Vitamin D Assays J. Clin. Endocrinol. Metab., May 1, 2008; 93(5): 1804 - 1808. [Abstract] [Full Text] [PDF]
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 H. J. Roth, H. Schmidt-Gayk, H. Weber, and C. Niederau Accuracy and clinical implications of seven 25-hydroxyvitamin D methods compared with liquid chromatography-tandem mass spectrometry as a reference Ann Clin Biochem, March 1, 2008; 45(2): 153 - 159. [Abstract] [Full Text] [PDF]
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 P. F. Lata and M. E. Elliott Patient Assessment in the Diagnosis, Prevention, and Treatment of Osteoporosis Nutr Clin Pract, June 1, 2007; 22(3): 261 - 275. [Abstract] [Full Text] [PDF]
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N. Binkley, R. Novotny, D. Krueger, T. Kawahara, Y. G. Daida, G. Lensmeyer, B. W. Hollis, and M. K. Drezner Low Vitamin D Status despite Abundant Sun Exposure J. Clin. Endocrinol. Metab., June 1, 2007; 92(6): 2130 - 2135. [Abstract] [Full Text] [PDF]
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 J. A. Schmidt Measurement of 25-Hydroxyvitamin D Revisited Clin. Chem., December 1, 2006; 52(12): 2304 - 2305. [Full Text] [PDF]
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G. Lensmeyer, D. Wiebe, N. Binkley, and M. Drezner The authors of the article cited above respond: Clin. Chem., December 1, 2006; 52(12): 2305 - 2306. [Full Text] [PDF]
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N. Binkley, M. K. Drezner, and B. W. Hollis Laboratory reporting of 25-hydroxyvitamin d results: potential for clinical misinterpretation. Clin. Chem., November 1, 2006; 52(11): 2124 - 2125. [Full Text] [PDF]
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