Parathyroid Hormone Actions on Bone and Kidney

Parathyroid hormone (PTH) acts on the kidney and bone through one common receptor in each organ. These actions, separately and together, serve to raise the blood calcium concentration. In the kidney, actions on the proximal tubule serve to decrease reabsorption of phosphorus and to activate the 1α-hydroxylase that leads to formation of active vitamin D. In the distal tubule, PTH serves to increase the reabsorption of calcium. In addition, actions of PTH on multiple cell types in bone also serve to regulate the proliferation and differentiation of these cell types. Here we consider the actions of PTH on its multiple target cells in the kidney and bone.