Question

Hypokalemia is caused by the following EXCEPT

• A. Cushing's syndrome
• B. Conn's syndrome
• C. Bartter's syndrome
• D. Addison's disease

Hint:

Three of these have too much mineralocorticoid effect; one has too little.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
We need to identify which of these four conditions does NOT cause low blood potassium.

Step 2: Key Formula or Approach:
Most of these conditions involve excess mineralocorticoid (aldosterone-like) activity, which drives potassium out of the body through the kidneys, while one of them instead involves a deficiency of these hormones.

Step 3: Detailed Explanation:
Cushing's syndrome, from excess cortisol, causes hypokalemia because very high cortisol levels can overwhelm the enzyme that normally protects the potassium-sparing part of the kidney tubule, giving cortisol a mineralocorticoid-like effect that increases potassium loss.
Conn's syndrome is primary hyperaldosteronism, where excess aldosterone directly increases potassium excretion by the kidney, causing hypokalemia as one of its hallmark features.
Bartter's syndrome is an inherited kidney tubule defect that mimics the effect of a loop diuretic, causing salt wasting, secondary hyperaldosteronism, and significant hypokalemia.
Addison's disease is primary adrenal insufficiency, where aldosterone production is deficient rather than excessive. Without enough aldosterone, the kidney fails to excrete potassium normally, so Addison's disease classically causes hyperkalemia, not hypokalemia.

Step 4: Final Answer:
So the condition that does NOT cause hypokalemia, and instead causes hyperkalemia, is Addison's disease.