Conn syndrome vs Cushing syndrome
How to tell Conn syndrome and Cushing syndrome apart when a board question makes them look alike.
Conn is aldosterone: hypertension plus hypokalemic metabolic alkalosis and low renin; Cushing is cortisol: striae, proximal weakness, hyperglycemia, and cortisol testing.
Side by side
Primary aldosterone excess causing resistant hypertension, hypokalemia, metabolic alkalosis, muscle weakness, and suppressed renin.
Cortisol excess causing central obesity, moon facies, proximal weakness, purple striae, glucose intolerance, hypertension, and infection risk.
Autonomous zona glomerulosa aldosterone secretion increases sodium retention while increasing potassium and hydrogen ion loss.
Excess glucocorticoid signaling drives protein catabolism, insulin resistance, immune suppression, and mineralocorticoid-like hypertension at high cortisol levels.
High aldosterone-to-renin ratio, low renin, hypokalemia, and metabolic alkalosis support Conn syndrome.
Elevated cortisol, failed low-dose dexamethasone suppression, or abnormal late-night salivary cortisol supports Cushing syndrome.
The trap
Both can cause hypertension and hypokalemia, but body habitus, glucose, renin/aldosterone, and cortisol testing separate them.
The repair move
For endocrine hypertension, decide whether the hormone story is aldosterone electrolyte wasting or cortisol phenotype.
Try a free question
CoreA patient has resistant hypertension, episodic weakness, hypokalemia, metabolic alkalosis, high plasma aldosterone, and low renin. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Conn syndrome. Primary aldosterone excess produces hypertension, hypokalemia, alkalosis, high aldosterone, and low renin.
Why the other choices are tempting
- B. Cushing syndrome should add cortisol-excess features and abnormal cortisol testing.
- C. Pheochromocytoma causes episodic catecholamine symptoms rather than low-renin aldosterone excess.
- D. Renal artery stenosis usually raises renin and aldosterone secondarily.
- E. Primary adrenal insufficiency causes hypotension, hyperkalemia, and low cortisol.
Flashcards
Tap a card to flip it.
What lab pattern points to Conn syndrome?
High aldosterone with low renin, hypokalemia, and metabolic alkalosis points to Conn syndrome.
What clinical pattern points to Cushing syndrome?
Central obesity, purple striae, proximal weakness, hyperglycemia, and cortisol excess point to Cushing syndrome.
Quick answers
What is the fastest way to tell Conn syndrome from Cushing syndrome?
Conn is aldosterone: hypertension plus hypokalemic metabolic alkalosis and low renin; Cushing is cortisol: striae, proximal weakness, hyperglycemia, and cortisol testing.
What is the key clue for Conn syndrome?
Primary aldosterone excess causing resistant hypertension, hypokalemia, metabolic alkalosis, muscle weakness, and suppressed renin.
What is the key clue for Cushing syndrome?
Cortisol excess causing central obesity, moon facies, proximal weakness, purple striae, glucose intolerance, hypertension, and infection risk.
What is the common trap with Conn syndrome vs Cushing syndrome?
Both can cause hypertension and hypokalemia, but body habitus, glucose, renin/aldosterone, and cortisol testing separate them.