Which hormone decreases the level of calcium?

NVS- 2025

Applied Physiology

Easy

Appeared in: NVS- 2025

Explanation

Calcitonin is the hormone responsible for decreasing blood calcium levels.
It is secreted by the parafollicular cells (C-cells) of the thyroid gland in response to high blood calcium (hypercalcemia).
Calcitonin lowers calcium by inhibiting bone resorption (breakdown) by osteoclasts, thus keeping calcium in the bones.
It also increases the excretion of calcium by the kidneys, removing excess calcium from the body through urine.

Option B: Glucocorticoids (e.g., cortisol) are primarily involved in stress response, inflammation, and metabolism. While chronic excess can lead to osteoporosis by affecting calcium balance, they are not the primary hormone that acutely decreases blood calcium.
Option C: Parathyroid hormone (PTH) has the exact opposite function. It is the primary hormone for increasing blood calcium levels when they are too low (hypocalcemia).
Option D: Mineralocorticoids (e.g., aldosterone) are primarily responsible for regulating sodium, potassium, and water balance, which affects blood volume and blood pressure. They do not have a direct or primary role in regulating 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 homeostasis as background academic context rather than a clinical decision trigger.
Nurses must monitor serum calcium levels in patients with thyroid or parathyroid disorders, especially after surgeries like thyroidectomy or parathyroidectomy, as the glands producing these key hormones are affected.
Understanding this hormonal balance is crucial for recognizing signs of hypocalcemia (e.g., tetany, Chvostek's sign) or hypercalcemia (e.g., lethargy, confusion) and intervening appropriately.
What if? If a patient has chronic kidney disease, their ability to excrete phosphate is impaired and Vitamin D activation is reduced. This leads to low calcium and high phosphate, causing a state of secondary hyperparathyroidism as the body constantly tries to raise calcium levels by releasing PTH.

How to Approach the Question

First, identify the key action in the question: "decreases the level of calcium".
Next, recall the main hormones involved in calcium regulation. The two primary antagonists are Calcitonin and Parathyroid Hormone (PTH).
Remember the mnemonic: Calci-ton-in "tones down" calcium in the blood.
Conversely, Parathyroid Hormone (PTH) Puts The Calcium High.
Evaluate the other options. Glucocorticoids and Mineralocorticoids are adrenal hormones with different primary functions (stress/metabolism and salt/water balance, respectively), making them less likely to be the primary regulator of calcium.
Select the hormone whose primary function matches the action described in the question.

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