Which hormone regulates blood levels of calcium?

Which hormone regulates blood levels of calcium?

• A. Luteinizing hormone
• B. Parathormone
• C. Thyroid stimulating hormone
• D. Adrenocorticotropic hormone

Answer: (B)

Calcium balance in the blood is regulated primarily by parathormone. When serum calcium is low, parathormone is released and raises calcium through three main actions: it stimulates bone to release calcium, increases calcium reabsorption in the kidneys, and promotes the production of active vitamin D, which enhances intestinal absorption of calcium. The combined effect is an increase in blood calcium toward normal levels. The other hormones listed regulate different organs (reproductive system, thyroid, and adrenal cortex) and do not directly control calcium levels, so they are not the regulators of blood calcium.

Calcium balance in the blood is regulated primarily by parathormone. When serum calcium is low, parathormone is released and raises calcium through three main actions: it stimulates bone to release calcium, increases calcium reabsorption in the kidneys, and promotes the production of active vitamin D, which enhances intestinal absorption of calcium. The combined effect is an increase in blood calcium toward normal levels. The other hormones listed regulate different organs (reproductive system, thyroid, and adrenal cortex) and do not directly control calcium levels, so they are not the regulators of blood calcium.