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.