Question

Assertion (A): Hyperkalemia is not a feature of ACTH deficiency (secondary adrenal insufficiency).

Reason (R): ACTH increases potassium reabsorption by the distal renal tubule.

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is NOT the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Remember that aldosterone, not ACTH, is the hormone that controls potassium at the distal tubule.

Answer 1

The Correct Option is C

Step 1: Check the Assertion.
Secondary adrenal insufficiency happens when the pituitary stops making enough ACTH, so cortisol production falls. Aldosterone, the hormone that controls sodium and potassium balance, is mainly controlled by the renin angiotensin system and by the potassium level itself, not by ACTH. Because aldosterone secretion stays largely normal, potassium handling by the kidney is not disturbed, and patients with ACTH deficiency do not usually show a raised potassium level. So the Assertion is true.

Step 2: Check the Reason.
The Reason claims that ACTH itself raises potassium reabsorption at the distal tubule. This is not accurate. It is aldosterone, not ACTH, that acts on the distal tubule, and its true effect is to increase sodium reabsorption while pushing potassium out into the urine, which is potassium loss, not potassium reabsorption. So the Reason names the wrong hormone and the wrong direction of effect, and it is false.

Step 3: Decide the relationship.
Since the Reason is false, it cannot serve as a valid explanation for the true Assertion, even though the Assertion itself stands correct for a different reason, namely preserved aldosterone secretion.

Step 4: Rule out the other codes.
The two codes that need R to be true do not fit, because the Reason misstates the hormone and its action. The code that needs A to be false does not fit, because hyperkalemia genuinely is not a typical feature of isolated ACTH deficiency.

Final Answer:
The Assertion is true but the Reason is false. The printed answer key for this question was illegible in the source paper, so this answer follows standard endocrine physiology.