VITAMIN D3 (1, 25 DIHYDROXYCHOLECALCIFEROL)

- (vitamin D3) which is synthesized in skincholecalciferolVitamin D is a fat soluble vitamin and exists in two main forms as from 7-dehydrocholesterol in response to sunlight exposure & Ergocalciferol(vitamin D2) present mainly in dietary sources. Both cholecalciferol & Ergocalciferol are converted to 25(OH) vitamin D in liver. - Testing for 25(OH) vitamin D is recommended as it is the best indicator of vitamin D nutritional status as obtained from sunlight exposure & dietary intake. For diagnosis of vitamin D deficiency it is recommended to have clinical correlation with serum 25(OH) vitamin D, serum calcium, serum PTH & serum alkaline - During monitoring of oral vitamin D therapy- suggested testing of serum 25(OH) vitamin D is after 12 weeks or 3 months of treatment. However, the required dosage of vitamin D supplements & time to achieve sufficient vitamin D levels show significant seasonal(especially winter) & individual variability depending on age, body fat, sun exposure, physical activity malabsorption, genetic factors(especially variable vitamin D receptor responses), associated liver or renal disease, syndromes and calcium or magnesium deficiency influencing the vitamin D metabolism Vitamin D toxicity is known but very rare. Kindly correlate clinically, repeat with fresh sample if indicated