Answer
Both parathyroid hormone and calctriol act to raise serum levels of Ca++ions, but they do this in different ways
Work Step by Step
Calcitriol stimulates the absorption of Ca++ from foods in the GI tract
PTH increases serum CA++ by stimulation of reabsorption of bone extracellular matrix. This releases Ca++ ions into the blood. PTH also slows loss of Ca++ ions in the urine. The combined effect is to raise serum levels of Ca++. Furthermore, PTH stimulates the kidneys to increase the secretion and release of calcitriol.
