Which hormone maintains serum calcium level?

AIIMS Delhi NO - 2017

Applied Physiology

Easy

Appeared in: AIIMS Delhi NO - 2017

Explanation

Parathyroid hormone (PTH) is the principal hormone that regulates serum calcium levels.
It is secreted by the parathyroid glands in response to low blood calcium (hypocalcemia).
PTH increases calcium levels by stimulating bone resorption (releasing calcium from bones), increasing reabsorption in the kidneys, and promoting intestinal absorption via Vitamin D activation.
This action ensures that calcium levels remain within the narrow physiological range required for critical bodily functions.

Option A: While the thyroid gland is involved in calcium homeostasis, its primary role is antagonistic to PTH. It produces calcitonin, which lowers blood calcium levels, primarily by inhibiting bone resorption. PTH is the main hormone that raises and maintains calcium levels.
Option B: Insulin's primary function is to regulate blood glucose levels by facilitating glucose uptake into cells. It does not have a direct role in maintaining serum calcium.
Option C: Gastrin is a digestive hormone that stimulates the secretion of gastric acid (hydrochloric acid) in the stomach. It plays no role in calcium regulation.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of serum calcium levels as background academic context rather than a clinical decision trigger.
Nurses must monitor serum calcium levels in patients with known parathyroid disorders (hyperparathyroidism or hypoparathyroidism) and in post-operative patients who have had thyroid or parathyroid surgery, as the glands can be inadvertently damaged or removed.
Signs of hypocalcemia (low calcium) include neuromuscular irritability, such as tingling (paresthesia), muscle cramps, and tetany. Key signs are Chvostek's sign (facial muscle twitching) and Trousseau's sign (carpopedal spasm).
Signs of hypercalcemia (high calcium) can be remembered with the mnemonic 'stones, bones, groans, and psychiatric overtones' (kidney stones, bone pain, abdominal pain/constipation, and confusion/depression).

How to Approach the Question

First, identify the key concept in the question stem: 'maintains serum calcium level'. This is a physiological regulation question.
Recall the major endocrine glands and the primary function of the hormones they secrete.
Associate the parathyroid glands directly with calcium regulation. The name itself ('para'-thyroid) hints at its relationship and location, but its function is distinct.
Evaluate the other options: Thyroid hormone's main role is metabolism (T3/T4), though it also secretes calcitonin for calcium reduction. Insulin controls glucose. Gastrin controls stomach acid.
Conclude that Parathyroid Hormone (PTH) is the primary hormone responsible for raising and maintaining calcium levels, making it the best answer.

Concept Tested & Keywords

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