Does the skin produce hormones that are essential for proper calcium absorption from the digestive tract, or does it produce calcitriol? If not, what role does the skin play in the process of calcium absorption?

1 Answer
Jan 15, 2018

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Calcium absorption requires assistance from Vitamin D. The active form of Vitamin D is known as #1,25#-Dihydroxy Cholecalciferol or Calcitriol.

Now,skin contains a precursor of this thing known as #7#-Dehydrocholesterol(Pre-cholecalciferol),which undergoes non enzymatic reaction due to UV ray of Sun light.

Now this Pre-cholecalciferol undergoes thermal isomerization over hours to form Cholecalciferol(Vitamin D),that gets absorbed to blood stream.

This Cholecalciferol is hydroxylated in liver to form #25#-Hydroxy-cholecalciferol. This thing when released again in to the circulation,binds to a specific type of globulin,which acts as main storage of Vitamin D.

After this thing comes to kidney it undergoes another hydroxylation,which can be of two types,one is forming of #1,25#-Dihydroxycholecalciferol or Calcitriol. This helps in calcium absorption.

Or,it can make #24,25#-Dihydroxycholecalciferol which is an inactive metabolite of Vitamin D