The concentration of which electrolyte is directly regulated by aldosterone?

UP NHM CHO 7 Sept 2022(shift-1st)

Applied Physiology

Easy

Appeared in: UP NHM CHO 7 Sept 2022(shift-1st)

Explanation

Aldosterone is the principal mineralocorticoid hormone responsible for regulating the body's sodium and potassium balance.
It acts on the distal tubules and collecting ducts of the kidneys to increase the reabsorption of sodium from the filtrate back into the blood.
This direct action on sodium channels and the sodium-potassium pump leads to sodium retention.
Because water follows sodium, this process also helps regulate extracellular fluid volume and blood pressure.

Option A: Calcium levels are not directly regulated by aldosterone. They are primarily controlled by a different set of hormones.
Option B: Iron balance is unrelated to aldosterone. Its regulation involves absorption from the diet and storage, controlled by the hormone hepcidin.
Option D: While the kidneys are involved in magnesium excretion, aldosterone is not its primary regulator. Parathyroid hormone has a more significant influence on magnesium reabsorption.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of electrolytes as background academic context rather than a clinical decision trigger.
Nurses must closely monitor sodium and potassium levels in patients with adrenal disorders (e.g., Addison's disease, Conn's syndrome) or those on medications affecting the RAAS (e.g., ACE inhibitors, spironolactone).
Understanding aldosterone's function is critical for managing patients with hypertension, heart failure, and kidney disease, as it directly impacts fluid volume and blood pressure.
What if a patient is prescribed spironolactone, an aldosterone antagonist? The nurse should anticipate and monitor for potential side effects like hyperkalemia (high potassium) and hyponatremia (low sodium), as the drug blocks aldosterone's sodium-retaining and potassium-excreting effects.

How to Approach the Question

First, identify the key terms in the question: 'electrolyte', 'regulated by', and 'aldosterone'.
Recall the function of aldosterone. It is a mineralocorticoid hormone, which signals its role in mineral (electrolyte) balance.
Remember that aldosterone is a key part of the Renin-Angiotensin-Aldosterone System (RAAS), which regulates blood pressure and fluid balance.
Associate aldosterone with its primary actions on the kidney: increasing sodium reabsorption and increasing potassium excretion.
Evaluate the options based on this knowledge. Calcium, iron, and magnesium are regulated by different hormonal and physiological pathways.
Conclude that sodium is the electrolyte most directly regulated by aldosterone's actions.

Concept Tested & Keywords

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E6 Nursing Fundamentals Taylor p. 773-775

E6 Physiology Guyton 4SAE Part 2B p. 53-55