JJ, Du Bois MB, Halpern S, Cournot-Witmer G, Garabedian M, Balsan S: In vitro action of 1,25-dihydroxycholecalciferol and 24,25- dihydroxycholecalciferol on matrix organization and mineral distribution in rabbit growth plate. Metab Bone Dis Relat Res 1982;4:135–142.
27Schlingmann KP, Kaufmann M, Weber S, Irwin A, Goos C, John U, et al: Mutations in CYP24A1 and idiopathic infantile hypercalcemia. N Eng J Med 2011;365:410–421.
28O’Keeffe DT, Tebben PJ, Kumar R, Singh RJ, Wu Y, Wermers RA: Clinical and biochemical phenotypes of adults with monoallelic and biallelic CYP24A1 mutations: evidence of gene dose effect. Osteoporosis Int 2016;27:3121–3125.
29Armbrecht HJ, Hodam TL, Boltz MA, Partridge NC, Brown AJ, Kumar VB: Induction of the vitamin D 24-hydroxylase (CYP24) by 1,25-dihydroxyvitamin D3 is regulated by parathyroid hormone in UMR106 osteoblastic cells. Endocrinology 1998;139:3375–3381.
30Reddy GS, Muralidharan KR, Okamura WH, Tserng KY, McLane JA: Metabolism of 1alpha,25-dihydroxyvitamin D(3) and its C-3 epimer 1alpha,25-dihydroxy-3-epi-vitamin D(3) in neonatal human keratinocytes. Steroids 2001;66:441–450.
31Bailey D, Veljkovic K, Yazdanpanah M, Adeli K: Analytical measurement and clinical relevance of vitamin D(3) C3-epimer. Clin Biochem 2013;46:190–196.
32Kamao M, Tatematsu S, Hatakeyama S, Sakaki T, Sawada N, Inouye K, et al: C-3 epimerization of vitamin D3 metabolites and further metabolism of C-3 epimers: 25-hydroxyvitamin D3 is metabolized to 3-epi-25-hydroxyvitamin D3 and subsequently metabolized through C-1alpha or C-24 hydroxylation. J Biol Chem 2004;279:15897–15907.
33Brown AJ, Ritter C, Slatopolsky E, Muralidharan KR, Okamura WH, Reddy GS: 1Alpha,25-dihydroxy-3-epi-vitamin D3, a natural metabolite of 1alpha,25-dihydroxyvitamin D3, is a potent suppressor of parathyroid hormone secretion. J Cell Biochem 1999;73:106–113.
34Carter GD, Jones JC, Shannon J, Williams EL, Jones G, Kaufmann M, et al: 25-Hydroxyvitamin D assays: potential interference from other circulating vitamin D metabolites. J Steroid Biochem Mol Biol 2015;164:134–138.
35Slominski AT, Janjetovic Z, Fuller BE, Zmijewski MA, Tuckey RC, Nguyen MN, et al: Products of vitamin D3 or 7-dehydrocholesterol metabolism by cytochrome P450scc show anti-leukemia effects, having low or absent calcemic activity. PloS One 2010;5:e9907.
36Byrdwell WC, Devries J, Exler J, Harnly JM, Holden JM, Holick MF, et al: Analyzing vitamin D in foods and supplements: methodologic challenges. Am J Clin Nutr 2008;88:554S-557S.
37Cai SS, Syage JA: Comparison of atmospheric pressure photoionization, atmospheric pressure chemical ionization, and electrospray ionization mass spectrometry for analysis of lipids. Anal Chem 2006;78:1191–1199.
38Adamec J, Jannasch A, Huang J, Hohman E, Fleet JC, Peacock M, et al: Development and optimization of an LC-MS/MS-based method for simultaneous quantification of vitamin D2, vitamin D3, 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3. J Sep Sci 2011;34:11–20.
39Singh RJ: Are clinical laboratories prepared for accurate testing of 25-hydroxy vitamin D? Clin Chem 2008;54:221–223.
40Muller MJ, Volmer DA: Mass spectrometric profiling of vitamin D metabolites beyond 25-hydroxyvitamin D. Clin Chem 2015;61:1033–1048.
41Haddad JG, Chyu KJ: Competitive protein-binding radioassay for 25-hydroxycholecalciferol. J Clin Endocrinol Metab 1971;33:992–995.
42Hummer L, Nilas L, Tjellesen L, Christiansen C: A selective and simplified radioimmunoassay of 25-hydroxyvitamin D3. Scand J Clin Lab Invest 1984;44:163–167.
43Bouillon R, Van Herck E, Jans I, Tan BK, Van Baelen H, De Moor P: Two direct (nonchromatographic) assays for 25-hydroxyvitamin D. Clin Chem 1984;30:1731–1736.
44Granado Lorencio F, Blanco-Navarro I, Perez-Sacrsitan B: Critical evaluation of assays for vitamin D status. Curr Opin Clin Nutr Metab Care 2013;16:734–740.
45Farrell CJ, Herrmann M: Determination of vitamin D and its metabolites. Best Pract Res Clin Endocrinol Metab 2013;27:675–688.
46Heijboer AC, Blankenstein MA, Kema IP, Buijs MM: Accuracy of 6 routine 25-hydroxyvitamin D assays: influence of vitamin D binding protein concentration. Clin Chem 2012;58:543–548.
47Farrell CJ, Martin S, McWhinney B, Straub I, Williams P, Herrmann M: State-of-the-art vitamin D assays: a comparison of automated immunoassays with liquid chromatographytandem mass spectrometry methods. Clin Chem 2012;58:531–542.
48Cashman KD, Kiely M, Kinsella M, Durazo-Arvizu RA, Tian L, Zhang Y, et al: Evaluation of Vitamin D Standardization Program protocols for standardizing serum 25-hydroxyvitamin D data: a case study of the program’s potential for national nutrition and health surveys. Am J Clin Nutr 2013;97:1235–1242.
49Jones G, DeLuca HF. High-pressure liquid chromatography: separation of the metabolites of vitamins D2 and D3 on small-particle silica columns. J Lipid Res 1975;16:448–453.
50Wootton AM: Improving the measurement of 25-hydroxyvitamin D. Clin Biochem Rev 2005;26:33–36.
51Bedner M, Phinney KW: Development and comparison of three liquid chromatography-atmospheric pressure chemical ionization/mass spectrometry methods for determining vitamin D metabolites in human serum. J Chromatogr A 2012;1240:132–139.
52Bailey D, Veljkovic K, Yazdanpanah M, Adeli K: Analytical measurement and clinical relevance of vitamin D(3) C3-epimer. Clin Biochem 2013;46:190–196.
53Herrmann M, Harwood T, Gaston-Parry O, Kouzios D, Wong T, Lih A, et al: A new quantitative LC tandem mass spectrometry assay for serum 25-hydroxy vitamin D. Steroids 2010;75:1106–1112.
54Higashi T, Shibayama Y, Fuji M, Shimada K: Liquid chromatography-tandem mass spectrometric
