Category:Vitamin D
From Ganfyd
This includes a range of compounds used at different doses prophylactically and therapeutically in Vitamin D deficiency (osteomalacia/rickets). Vitamin D compounds play an important role in calcium homeostasis. As a fat-soluble vitamin, it is stored in the liver. They have the potential for toxicity at high, prolonged doses with the induction of hypercalcaemia and are perhaps best classed as hormones as actually, with enough sunlight, the body can meet its own needs.
The therapeutic indications for the various Vitamin D compounds differ, reflecting the metabolism of Vitamin D and perhaps that they are slighly different hormones, with effects on more than just calcium metabolism. Alphacalcidol is the compound of choice in renal failure. Ergocalciferol (Calciferol) is used in osteomalacia or rickets. The only low dose oral Vitamin D compound demonstrated to reduce osteoporotic fractures in the institutionalised elderly is colecalciferol. Perhaps this is because of its effects on muscle function.
Rarely amongst vitamins, Vitamin D supplementation without an overt deficiency state (except osteoporosis?) may be associated with reduced mortality[1].
Suggestions of wider roles of Vitamin D and association of a lack of it with bowel cancer and other conditions have been made. These are incompletely evaluated. However they have a strong basis as over human 229 genes are regulated by the nuclear vitamin D receptor [2].
Measuring Vitamin D levels in the blood can be useful clinically but comes with several caveats:
- Levels are seasonal (lowest in winter)
- There is minimal evidence and certainly no cost effectiveness evidence in many common subpopulations where enthusiasts recommend their screening use. The evidence relates to patients assessed by experienced secondary care bone metabolism services.
- Levels are a function of at least 3, and possibly 4 genes coding for 7-DHC reductase, 25-hydroxylase CYP2R1, CYP24A1 and the vitamin D binding-protein and it is unknown how and if this needs correcting for as of 2010
- Assays can have various and differing reasons for inconsistent performance. The present gold standard is liquid chromatography-tandem mass spectrometry and as recently as 2010 assay variation was such that the proportion of patients with a vitamin D level below 50nmol/L varied from 8% to 43%[3].
References
- ↑ Autier P, Gandini S. Vitamin D Supplementation and Total Mortality: A Meta-analysis of Randomized Controlled Trials. Archives of internal medicine. 2007 Sep 10; 167(16):1730-7.(Link to article – subscription may be required.)
- ↑ Ramagopalan SV, Heger A, Berlanga AJ, Maugeri NJ, Lincoln MR, Burrell A, Handunnetthi L, Handel AE, Disanto G, Orton SM, Watson CT, Morahan JM, Giovannoni G, Ponting CP, Ebers GC, Knight JC. A ChIP-seq defined genome-wide map of vitamin D receptor binding: associations with disease and evolution. Genome research. 2010 Oct; 20(10):1352-60.(Link to article – subscription may be required.)
- ↑ Snellman G, Melhus H, Gedeborg R, Byberg L, Berglund L, Wernroth L, Michaëlsson K. Determining vitamin D status: a comparison between commercially available assays. PloS one. 2010; 5(7):e11555.(Epub) (Link to article – subscription may be required.)
Pages in category "Vitamin D"
The following 13 pages are in this category, out of 13 total.
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