3 Quick Tips for Conn syndrome HTN

Conn syndrome (primary hyperaldosteronism) is one of those “slam-dunk if you recognize it” causes of secondary hypertension—because the labs and physiology line up beautifully. If you need a fast, shareable way to nail it on USMLE, here are 3 quick tips that cover recognition, confirmation, and management—plus an easy mnemonic you can recall under pressure.

Tip 1: Recognize the classic pattern — HTN + hypokalemic metabolic alkalosis + low renin

Think: “aldosterone = salt saver, potassium waster, hydrogen waster.”

The high-yield triad

Hypertension (often resistant)
Hypokalemia (may be spontaneous or unmasked by diuretics)
Metabolic alkalosis (from increased H $^+$ secretion by $\alpha$ -intercalated cells)

Core lab signature (most testable)

↑ Aldosterone
↓ Renin
↑ Aldosterone-to-renin ratio (ARR)

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One-liner: Conn syndrome is autonomous aldosterone → Na $^+$ retention (HTN) with K $^+$ and H $^+$ wasting (hypokalemic metabolic alkalosis) and suppressed renin.

Quick differentiation table (USMLE style)

Condition	Aldosterone	Renin	Key clue
Primary hyperaldosteronism (Conn)	↑	↓	ARR high; adrenal source
Secondary hyperaldosteronism (renal artery stenosis, renin tumor, HF/cirrhosis)	↑	↑	Renin-driven; often vascular/volume clues
Liddle syndrome	↓	↓	ENaC gain-of-function; low aldosterone
Apparent mineralocorticoid excess / licorice	↓	↓	11 $\beta$ -HSD2 inhibited/defective

Tip 2: Use the “Screen → Confirm → Localize” workflow

This is a common Step 2-style setup: pick the next best step.

Step A — Screen with ARR

Best screening test: Plasma aldosterone-to-renin ratio (ARR)
Screen especially in:
- Resistant HTN (≥3 meds)
- HTN + hypokalemia
- HTN with adrenal incidentaloma
- Early-onset HTN or family history of early strokes

Step B — Confirm with suppression testing

If screening suggests Conn, confirm inappropriate aldosterone secretion:

Saline infusion test (classic): aldosterone should suppress in normal physiology
Other options you may see: oral salt loading, fludrocortisone suppression, captopril challenge (institution-dependent)

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One-liner: If aldosterone stays high despite salt/volume, it’s acting autonomously → primary hyperaldosteronism.

Step C — Localize with imaging + adrenal venous sampling (AVS)

CT adrenal helps find masses but can be misleading (incidentalomas are common)
Adrenal venous sampling (AVS) is the gold standard for lateralization in many surgical candidates:
- Distinguishes unilateral adenoma vs bilateral hyperplasia

USMLE pearl: A visible adrenal nodule on CT does not guarantee it’s the source of aldosterone.

Tip 3: Treat based on laterality — Unilateral = cut it out; bilateral = block it

Management is straightforward once you know if it’s one-sided or both sides.

Unilateral aldosterone-producing adenoma

Treatment: Laparoscopic adrenalectomy
Expect:
- Improved BP (sometimes cured)
- Improved potassium and alkalosis

Bilateral adrenal hyperplasia

Treatment: Mineralocorticoid receptor antagonists
- Spironolactone (watch for gynecomastia, decreased libido, menstrual irregularities)
- Eplerenone (more selective; fewer sex-hormone side effects)

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One-liner: Unilateral = surgery; bilateral = spironolactone/eplerenone.

A quick visual mnemonic: “Conn = C.O.N.N.”

Picture aldosterone as a “salt-hungry boss” giving orders in the collecting duct:

C — Cardiovascular: HTN from Na $^+$ and water retention
O — Output: K $^+$ Out (hypokalemia)
N — pH: Net alkalosis (H $^+$ secretion → metabolic alkalosis)
N — Negative renin: renin low (feedback suppression)

Memory hook: “Conn keeps the Circulation pressured, pushes Out potassium, makes pH Not acidic, and renin goes Negative.”

Rapid-fire USMLE pitfalls (don’t miss these)

Normal K $^+$ doesn’t exclude Conn (many patients are normokalemic).
Conn is a cause of secondary HTN—think about it when HTN is resistant or early onset.
Liddle syndrome can look similar clinically (HTN + hypokalemic alkalosis) but has low aldosterone → treat with amiloride/triamterene, not spironolactone.
Metabolic alkalosis in Conn is driven by aldosterone effects on the collecting duct:
- Principal cells: ↑ ENaC → lumen more negative → promotes K $^+$ secretion
- $\alpha$ -intercalated cells: ↑ H $^+$ secretion → alkalosis

Quick recap (shareable)

Screen: ARR (↑ aldosterone, ↓ renin)
Clue: HTN + hypokalemic metabolic alkalosis
Treat: Unilateral = adrenalectomy; bilateral = spironolactone/eplerenone