Vitamin D Deficiency: Vitamin D Production and Effects

00:01 Let’s take a look at Vitamin D pathologies.

00:05 Begin by discussion of Vitamin D by looking at the different ways in which Vitamin D is provided to us in the active form.

00:14 Vitamin D can be taken up by food; Vitamin D can come from the skin with the help of UV light.

00:24 Rarely can Vitamin D deficiency take place in developed countries through dietary deficiency, but it could very much occur with lack of exposure to the sun.

00:37 This then gets into circulation, but this would be the inactive form.

00:41 The first place that it goes to would be to the liver and at the site of liver, it gets 25-hydroxylated.

00:49 This is the major circulating type of Vitamin D, 25-hydroxylated Vitamin D will then turn down to the kidney.

00:58 Here, with the help of 1-alpha-hydroxylase, because of PTH working upon it will stimulate the 1-alpha-hydroxylase resulting in the active compound of calcitriol or 1,25 dihydroxycholecalciferol.

01:11 The actions of this on the intestine… remember that Vitamin D is lipid soluble… the lipid soluble vitamins are ADEK… A, D, E, K.

01:24 The D, Vitamin D, will pass through the membrane, act upon the nucleus and so, therefore, bring about transcription/translation where you can then reabsorb your calcium from the intestine and Vitamin D works upon the kidney to reabsorb both calcium and phosphate whereas PTH only reabsorbs calcium.

01:47 Production effects of Vitamin D 1,25 dihydroxycholecalciferol reabsorbs your calcium.

01:54 Unlike PTH, Vitamin D does not promote renal phosphate wasting.

01:58 In fact, it promotes reabsorption.