PTH is produced in the parathyroid gland, while calcitriol is made in the kidney.

甲状旁腺产生甲状旁腺激素，肾脏产生骨化三醇。

The amount of calcium and circulation is mainly regulated by two hormones parathyroid hormone(PTH) and calcitriol.

钙含量和循环主要受甲状旁腺激素（PTH）和骨化三醇两种激素调节。

25-hydroxy-vitamin D then travels to the kidneys, where the enzyme 1-alpha-hydroxylase converts it to 1,25 hydroxy-vitamin D, or calcitriol, which is the active form of vitamin D.

之后25-羟维生素D被运送至肾脏，在1-α-羟化酶的作用下被转化为1，25-二羟维生素D，即骨化三醇，它是维生素D的活性形式。

At the same time, it stimulates production of calcitriol which promotes absorption of calcium in the small intestine, while also increases reabsorption in the kidney.

同时，它刺激骨化三醇产生，促进小肠对钙的吸收，同时也增加肾脏重吸收。

The parathyroid hormone gets the bones to release calcium, and gets the kidneys to reabsorb more calcium so it's not lost in the urine as well as synthesize calcitriol also known as 1,25-dihydroxycholecalciferol also known as active vitamin D.

甲状旁腺激素作用于骨骼使其释放钙离子，也作用于肾脏而增加钙的重吸收，这样钙就不会随尿液排出；以及用于合成骨化三醇，也称为1，25-二羟基胆钙化固醇，又叫活性维生素D。