Calcium metabolism is regulated by which gland?

Appeared in: ISRO 2024

Explanation

Calcium homeostasis is maintained by hormones from two different glands.
The parathyroid glands secrete Parathyroid Hormone (PTH) when blood calcium is low, which acts to raise calcium levels.
The parafollicular cells of the thyroid gland secrete Calcitonin when blood calcium is high, which acts to lower calcium levels.
Because both glands secrete essential regulatory hormones, they are both involved in the regulation of calcium metabolism.

Option A: This option is only partially correct. While the thyroid gland secretes calcitonin to lower blood calcium, it is not the only gland involved. The parathyroid gland plays a more critical role in preventing hypocalcemia.
Option B: This option is only partially correct. The parathyroid gland secretes PTH to raise blood calcium, but the thyroid gland's secretion of calcitonin is also part of the overall regulatory system.
Option C: The pituitary gland, often called the 'master gland,' regulates many other endocrine functions (like thyroid-stimulating hormone, TSH), but it does not directly secrete the primary hormones (PTH and Calcitonin) that control blood calcium levels.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of calcium metabolism as background academic context rather than a clinical decision trigger.
Nurses must closely monitor serum calcium levels in patients post-thyroidectomy or parathyroidectomy, as damage to these glands can severely disrupt calcium balance.
Clinical signs of hypocalcemia include Trousseau's sign (carpopedal spasm) and Chvostek's sign (facial muscle twitching), which are critical for nurses to assess.
Hypercalcemia can present with symptoms remembered by the mnemonic 'stones, bones, groans, and psychiatric overtones' (renal stones, bone pain, abdominal pain, and confusion), requiring prompt nursing assessment and intervention.

How to Approach the Question

First, identify the key concept in the question stem: the regulation of 'calcium metabolism'.
Recall the major hormones involved in calcium balance. The two primary ones are Parathyroid Hormone (PTH) and Calcitonin.
Next, identify the endocrine glands responsible for secreting these hormones. PTH is from the parathyroid glands, and Calcitonin is from the thyroid gland.
Evaluate the given options. Option A (Thyroid) and Option B (Parathyroid) are both involved.
Look for an option that encompasses both glands. Option D, 'Both A & B', correctly identifies that both glands are integral to calcium regulation.
Eliminate the Pituitary gland (Option C) as it is not the primary regulator of calcium.

Concept Tested & Keywords

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E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 2 — Subpart A (pp 1-239 of 478) p. 163-165

E6 Physiology Essentials Sembulingam 10e Part 2 pp. 49-51, 55-57

Practise the full ISRO 2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.