Question

Hormones involved in calcium metabolism are:
(A). FSH
(B). Vitamin D
(C). PTH
(D). Calcitonin
Choose the correct answer from the options given below:

• A. (A), (B) and (C) only.
• B. (A), (B) and (D) only.
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

Remember the "classic triad" of calcium regulation: PTH (raises calcium), Calcitonin (lowers calcium), and Vitamin D (helps absorb calcium).
FSH is strictly reproductive and can be easily eliminated.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Calcium homeostasis is vital for nerve transmission, muscle contraction, and skeletal integrity.
It is regulated by a coordinated endocrine feedback loop involving three primary hormones acting on the bones, kidneys, and intestines.

Step 2: Detailed Explanation:
- Parathyroid Hormone, PTH (C): Secreted by the parathyroid glands in response to low blood calcium, it increases calcium levels by mobilizing it from bone, increasing renal reabsorption, and stimulating Vitamin D activation.
- Calcitonin (D): Secreted by the thyroid parafollicular cells in response to high blood calcium, it acts to lower calcium levels by inhibiting bone resorption.
- Active Vitamin D (B): Synthesized in a pathway ending in the kidneys, it acts as a steroid hormone to increase calcium absorption in the small intestine.
- Follicle-Stimulating Hormone, FSH (A): A gonadotropin involved in reproductive physiology and regulation of the gonads, with no direct primary role in calcium metabolism.
Therefore, (B), (C), and (D) are the hormones directly involved in calcium metabolism.

Step 3: Final Answer:
The correct option is (D).