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Free 25OH Vitamin D ELISA

  • Regulatory status:RUO
  • Type:Sandwich ELISA, HRP-labelled antibody
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Cat. No. Size Price

KAPF1991 96 wells (1 kit)
PubMed Product Details
Technical Data

Cat # changed from RKARF1991R to KAPF1991


Sandwich ELISA, HRP-labelled antibody



Sample Requirements

10 µl/well


At ambient temperature. Upon receipt, store the product at the temperature recommended below.



Calibration Range

35-2.4 pg/ml

Limit of Detection

2,4 pg/ml

Inter-assay (Run-to-Run)

6,1 %



Incubation time: 1h30 min/30 min/ 20 min at 37°C with shaking

Research topic

Bone and cartilage metabolism


Vitamin D is a steroid hormone involved in the intestinal absorption of calcium and the regulation of calcium homeostasis. There are two different forms of Vitamin D, named D3 and D2, which are very similar in structure. The D2 is a synthetic product, which is predominantly absorbed by fortified food. Physiological Vitamin D3 levels result not only from dietary uptake but also by biosynthesis of 7-dehydrocholesterol and UV-light in skin because of sun exposure. Vitamin D deficiency can result from inadequate intake coupled with inadequate sunlight exposure, disorders that limit its absorption, conditions that impair conversion of vitamin D into active metabolites, such as liver or kidney disorders, or, rarely, by a number of hereditary disorders. Deficiency results in impaired bone mineralization, and leads to bone softening diseases, rickets in children and osteomalacia in adults, and possibly contributes to osteoporosis. Research has indicated that vitamin D deficiency is linked to colon cancer; conflicting evidence links vitamin D deficiency to other forms of cancer. In the liver, the vitamin is hydroxylated to 25-hydroxyvitamin D (25-OH Vitamin D), the major circulating metabolite of Vitamin D. Although 1,25-(OH)2 Vitamin D portrays the biological active form of Vitamin D, which is synthesized in the kidney, it is widely accepted that the measurement of circulating 25-OH Vitamin D provides better information with respect to patients Vitamin D status and allows its use in diagnose hypovitaminosis . The concentration of 25-OH Vitamin D decreases with age and a deficiency is common among elderly persons. Clinical applications of 25-OH Vitamin D measurements are the diagnosis and therapy control of postmenopausal osteoporosis, rickets, osteomalacia, renal osteodystrophy, pregnancy, neonatal hypocalcemia and hyperparathyro­idism. Vitamin D intoxication mostly occurs during a large intake of pharmaceutical preparations of Vitamin D and may lead to hypercalcemia, hypercalcuria and nephrocalcinosis in susceptible infants.

Product References (8)


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  • Lee MJ, Kearns MD, Smith EM, Hao L, Ziegler TR, Alvarez JA, Tangpricha V. Free25-Hydroxyvitamin D Concentrations in Cystic Fibrosis. Am J Med Sci. 2015Nov;350(5):374-9. doi: 10.1097/MAJ.0000000000000592. Erratum in: Am J Med Sci.2016 Feb;351(2):227. PubMed PMID: 26512456; PubMed Central PMCID: PMC4629503. See more on PubMed
  • Nielson CM, Jones KS, Chun RF, Jacobs JM, Wang Y, Hewison M, Adams JS, SwansonCM, Lee CG, Vanderschueren D, Pauwels S, Prentice A, Smith RD, Shi T, Gao Y,Schepmoes AA, Zmuda JM, Lapidus J, Cauley JA, Bouillon R, Schoenmakers I, Orwoll ES; Osteoporotic Fractures in Men (MrOS) Research Group. Free 25-HydroxyvitaminD: Impact of Vitamin D Binding Protein Assays on Racial-Genotypic Associations. JClin Endocrinol Metab. 2016 May;101(5):2226-34. doi: 10.1210/jc.2016-1104. Epub2016 Mar 23. PubMed PMID: 27007693; PubMed Central PMCID: PMC4870848. See more on PubMed
  • Schwartz JB, Lai J, Lizaola B, Kane L, Markova S, Weyland P, Terrault NA,Stotland N, Bikle D. A comparison of measured and calculated free 25(OH) vitamin D levels in clinical populations. J Clin Endocrinol Metab. 2014 May;99(5):1631-7.doi: 10.1210/jc.2013-3874. Epub 2014 Jan 31. PubMed PMID: 24483159; PubMedCentral PMCID: PMC4010704. See more on PubMed
  • Schwartz JB, Lai J, Lizaola B, Kane L, Weyland P, Terrault NA, Stotland N,Bikle D. Variability in free 25(OH) vitamin D levels in clinical populations. JSteroid Biochem Mol Biol. 2014 Oct;144 Pt A:156-8. doi:10.1016/j.jsbmb.2013.11.006. Epub 2013 Nov 15. Review. PubMed PMID: 24240067;PubMed Central PMCID: PMC4022715. See more on PubMed
  • Sollid ST, Hutchinson MY, Berg V, Fuskevåg OM, Figenschau Y, Thorsby PM, JordeR. Effects of vitamin D binding protein phenotypes and vitamin D supplementation on serum total 25(OH)D and directly measured free 25(OH)D. Eur J Endocrinol. 2016Apr;174(4):445-52. doi: 10.1530/EJE-15-1089. Epub 2016 Jan 5. PubMed PMID:26733479; PubMed Central PMCID: PMC4763092. See more on PubMed
  • van Hoof HJ, Swinkels LM, Ross HA, Sweep CG, Benraad TJ. Determination ofnon-protein-bound plasma 1,25-dihydroxyvitamin D by symmetric (rate) dialysis.Anal Biochem. 1998 May 1;258(2):176-83. PubMed PMID: 9570827. See more on PubMed
Summary References (7)

References to 25-OH-Vitamin-D

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  • Hollis BW. Editorial: The determination of circulating 25-hydroxyvitamin D: noeasy task. J Clin Endocrinol Metab. 2004 Jul;89(7):3149-51. PubMed PMID:15240585. See more on PubMed
  • Lips P. Vitamin D physiology. Prog Biophys Mol Biol. 2006 Sep;92(1):4-8. Epub 2006 Feb 28. Review. PubMed PMID: 16563471. See more on PubMed
  • Macdonald HM, Mavroeidi A, Fraser WD, Darling AL, Black AJ, Aucott L, O'Neill F, Hart K, Berry JL, Lanham-New SA, Reid DM. Sunlight and dietary contributionsto the seasonal vitamin D status of cohorts of healthy postmenopausal womenliving at northerly latitudes: a major cause for concern? Osteoporos Int. 2011Sep;22(9):2461-72. doi: 10.1007/s00198-010-1467-z. Epub 2010 Nov 18. Erratum in: Osteoporos Int. 2011 Sep;22(9):2473-4. PubMed PMID: 21085934. See more on PubMed
  • Mavroeidi A, O'Neill F, Lee PA, Darling AL, Fraser WD, Berry JL, Lee WT, Reid DM, Lanham-New SA, Macdonald HM. Seasonal 25-hydroxyvitamin D changes in British postmenopausal women at 57 degrees N and 51 degrees N: a longitudinal study. JSteroid Biochem Mol Biol. 2010 Jul;121(1-2):459-61. doi:10.1016/j.jsbmb.2010.03.038. Epub 2010 Mar 17. PubMed PMID: 20302933. See more on PubMed
  • Snellman G, Melhus H, Gedeborg R, Byberg L, Berglund L, Wernroth L,Michaëlsson K. Determining vitamin D status: a comparison between commerciallyavailable assays. PLoS One. 2010 Jul 13;5(7):e11555. doi:10.1371/journal.pone.0011555. Erratum in: PLoS One. 2010;5(9). doi:10.1371/annotation/23307aa4-726e-4f11-86c0-8a292be33517. PubMed PMID: 20644628;PubMed Central PMCID: PMC2903481. See more on PubMed
  • Tsur A, Metzger M, Dresner-Pollak R. Effect of different dress style onvitamin D level in healthy young Orthodox and ultra-Orthodox students in Israel. Osteoporos Int. 2011 Nov;22(11):2895-8. doi: 10.1007/s00198-010-1492-y. Epub 2010Nov 26. PubMed PMID: 21110005. See more on PubMed
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