PTH and Calcitonin with Rickets

[futuredocno]

I think I am overthinking this but I am very confused why you would have increased parathyroid hormone levels with rickets.
Because rickets has decreased vitamin D and I know that PTH increased calcium when it is low so i understand that, but because it increased calcium levels, why would there be low vitamin D still because PTH is supposed to increase calcium???

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[Neuroplasticity]

I think you may be thinking about cause and effect of rickets the wrong way around. Low vitamin D causes rickets, rickets does not cause low vitamin D. So having rickets means you have low vitamin D.
Vitamin D increases intestine Ca2+ absorption, so when you have low vitamin D, you have less intestine Ca2+ absorption which leads to low blood Ca2+. To raise blood Ca2+, you increase parathyroid hormone levels.

 

[futuredocno]

Thank you!