Let’s take a look at Vitamin D pathologies.
Begin by discussion of Vitamin D by looking
at the different ways in which Vitamin D is
provided to us in the active form.
Vitamin D can be taken up by food; Vitamin
D can come from the skin with the help of
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.
This then gets into circulation, but this
would be the inactive form.
The first place that it goes to would be to
the liver and at the site of liver, it gets
This is the major circulating type of Vitamin
D, 25-hydroxylated Vitamin D will then turn
down to the kidney.
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.
The actions of this on the intestine… remember
that Vitamin D is lipid soluble… the lipid
soluble vitamins are ADEK…
A, D, E, K.
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
Production effects of Vitamin D 1,25 dihydroxycholecalciferol
reabsorbs your calcium.
Unlike PTH, Vitamin D does not promote renal
In fact, it promotes reabsorption.