Fasting serum phosphate concentration is regulated primarily by which gland?

Fasting serum phosphate concentration is regulated primarily by which gland?

• A. Pancreas
• B. Skeleton
• C. Parathyroid glands
• D. Small intestine

Answer: (C)

Phosphate levels are controlled mainly by parathyroid hormone from the parathyroid glands. When PTH is released, it acts on the kidneys to decrease phosphate reabsorption in the proximal tubule, increasing phosphate excretion and lowering serum phosphate. It also influences bone to release calcium and phosphate, but the renal phosphaturic effect is the dominant action that keeps fasting phosphate in check. The pancreas and small intestine do not regulate phosphate via a single gland, and the skeleton is a reservoir rather than a regulatory gland. So the parathyroid glands are the primary regulators of fasting serum phosphate.

Phosphate levels are controlled mainly by parathyroid hormone from the parathyroid glands. When PTH is released, it acts on the kidneys to decrease phosphate reabsorption in the proximal tubule, increasing phosphate excretion and lowering serum phosphate. It also influences bone to release calcium and phosphate, but the renal phosphaturic effect is the dominant action that keeps fasting phosphate in check. The pancreas and small intestine do not regulate phosphate via a single gland, and the skeleton is a reservoir rather than a regulatory gland. So the parathyroid glands are the primary regulators of fasting serum phosphate.