The [[Calcium#Active Vitamin D Synthesis|activation of vitamin D]] is regulated by the kidneys under the influence of another hormone, [[Calcium#Parathyroid Hormone (PTH)|PTH]]. | The [[Calcium#Active Vitamin D Synthesis|activation of vitamin D]] is regulated by the kidneys under the influence of another hormone, [[Calcium#Parathyroid Hormone (PTH)|PTH]]. |