Vitamin D Deficiency Vitamin D deficiency is becoming a significant health concern. This is more of a life style disease due to lack of sun exposure/dietry intake/inapproporiate supplementation Impact of Vitamin D Deficiency: Usually asymptomatic but may present with fatigue, muscle weakness. Not only causative of bone disease( rickets or osteomalacia) as considered in the past, but is also associated with risk of development of cancer, diabetes, hypertension, cardiovascular disease, obesity, infertility, anemia, brain damage, numbness, back pain, paralysis, autoimmune disorders. Vitamin D can influence 300 genes in our body. Vitamin D receptors are present in various tissue and organs. Maternal deficiency of vitamin D is linked with abnormal fetal growth and gestational diabetes.Study published in year 2010 in JAPI shows very high prevalence (96.7%) of vitamin D deficiency in Asian Indian patients with fragility hip fracture. Psychitric patients presenting with their first episode of psychosis are more likely to have vitamin D deficiency. Vitamin D deficiency also inhibits immune response to TB and other infectious organisms. Determination of Vitamin D: Vitamin D status is measured by 25 (OH) Vitamin D. 25 –hydroxyl(OH) Vitamin D is an indiactor of storage. Concentration of 1,25 (OH) Vitamin D , correlates more with kidney function than with Vitamin D deficiency. Forms of Vitamin D: Two major forms- Vitamin D2 & Vitamin D3. Vitamin D2( Ergocalciferol) is synthesized by plants and not produced in the body. Vitamin D3 ( Cholecalciferol) is made by bare skin when exposed to sunlight. Most healthy fish contains Vitamin D3. To get a accurate reading, total amount of Vitamin D should measure both Vitamin D2 & D3. Approach to Measurement of Vitamin D: is very important in selecting technology for accurate value. Available technologies include immunoassays, HPLC, Liquid chromatography-tandem mass spectrometry ( LC-MS/MS). Immunoassay technology is although cheap compared to LC-MS/MS technology but cannot measure both Vitamin D2 & Vitamin D3. Binding protein shows higher affinity for Vitamin D3 and most of these immunoassay kits and can measure only Vitamin D3.Immunoassays have diminished capacity to detect Vitamin D2. An assay that can detect 100 percent of both Vitamin D2 & Vitamin D3 accurately helps to assess the actual Vitamin D status. Seprate measurement of Vitamin D2 & Vitamin D3 is necessary to monitor therapy. LC-MS/MS is a gold standard technology to accurately measure both Vitamin D2 & Vitamin D3. In LC-MS/MS technique, binding protein is first precipitated and then Vitamin D is extracted by organic solvents. LC-MS/MS technology is highly specific, reproducibility for low, medium & high values is excellent as standard curve is used in every test.Beside measuring Vitamin D2 & Vitamin D3, LC-MS/MS can also chromatographically seprate interferences called epimers thus providing accurate values of Vitamin D2 & Vitamin D3. LC-MS/MS assays are available both for only measuring Vitamin D2 & Vitamin D3 and assay where epimers are also measured. Under- or over-estimation of Vitamin D may occur due to coeluting epimers .
Posted on: Tue, 28 Oct 2014 11:46:36 +0000
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