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Vitamin D
Submitted by:Prabhjot kaur
Introduction
• It is the collective name given to antirachitic substance.
• These are synthesized in body and found in foods activated by UV radiation.
• D1: mixture of antirachitic substances found in food.
• D2: calciferol,present in irradiated food such as yeast ,fungi ,bread.
• D3: cholecalciferol ,synthesized in skin under the influence of UV rays.
Action of calcitriol
• It enhances absorption of calcium and phosphate from intestine.
• It enhances resorption of calcium and phosphate from bone
• It enhances proximal tubular reabsorption of both calcium and phosphate in kidney
Vitamin D deficiency
• In this ,plasma calcium and phosphate tend to fall due to inadequate intestinal absorption.
• Rickets in children
• Osteomalacia in adults may occur.
Hypervitaminosis D
• It may occur due to chronic ingestion of large doses or due to increased sensitivity of tissues to vitamin D.
• Hypercalcaemia,weakness,fatigue,vomiting,diarrhoea,renal stones,hypertension.
• Even coma may occur.
Treatment
• Its dose should contain the vitamin,low calcium diet,plenty of fluid,and corticosteroid.
Uses
• In prophylaxis : in this prophylactic treatment may be given in obstructive jaundice and other conditions.
• Metabolic rickets; these are group of condition in which the tissues does not give response to vit.D.
Vitamin D resistant rickets
• X linked heredity diseases in which vitamin d metabolism is normal and calcium and phosphate metabolism is deranged.
• Phosphate with high dose of calcitrol.
Vitamin d dependent rickets
• It is a genetic disorder occur due deficiency of renal hydroxylating mechanism.
• Normal doses of calciferol can v given
Renal rickets
• Renal rickets: conversion of 25-OHD3 into calcitriol does not occur due to the chronic renal diseases.
• In postmenopausal osteoporosis:it is an age related problem.in this there is decrease in calcium absorption from gut.
Vitamin D3 and calcium is used
Fanconi syndrome
• In this case vitamin d raise the lowered phosphate level that occur in this condition
Interactions
• Cholestyramine and chronic use of liquid paraffin can reduces vitamin d absorption.
• Phenytoin and phenobarbitone reduces the responsiveness of target tissues to calcitriols.
• Prolong uses of both may cause rickets and osteomalacia.