Which action is performed by parathyroid hormone in the kidney?

Which action is performed by parathyroid hormone in the kidney?

• A. Increase calcium reabsorption.
• B. Increase phosphate reabsorption.
• C. Decrease calcium reabsorption.
• D. Decrease phosphate excretion.

Answer: (A)

Parathyroid hormone raises calcium levels by acting on the kidney to reabsorb more calcium in the distal tubule. It binds receptors in the distal tubule and triggers signaling that increases the presence and activity of calcium channels and transporters, moving calcium from the filtrate back into the blood. At the same time, PTH reduces phosphate reabsorption in the proximal tubule, leading to more phosphate being excreted in urine, and it also promotes production of active vitamin D to boost gut calcium absorption. So the direct renal action you’d expect is increased calcium reabsorption, which is why that option is the best choice.

Parathyroid hormone raises calcium levels by acting on the kidney to reabsorb more calcium in the distal tubule. It binds receptors in the distal tubule and triggers signaling that increases the presence and activity of calcium channels and transporters, moving calcium from the filtrate back into the blood. At the same time, PTH reduces phosphate reabsorption in the proximal tubule, leading to more phosphate being excreted in urine, and it also promotes production of active vitamin D to boost gut calcium absorption. So the direct renal action you’d expect is increased calcium reabsorption, which is why that option is the best choice.