Cardiovascular · Year 1 · from Cardiovascular
Case 2: Primary Aldosteronism - Secondary Hypertension
Clinical Image
Source: Radiopaedia - Adrenal adenoma - Educational use
Patient Presentation
A 38-year-old woman is referred to endocrinology for evaluation of resistant hypertension. Despite taking three antihypertensive medications at maximum doses (including a diuretic), her blood pressure remains elevated. She has been experiencing muscle cramps, weakness, and fatigue. Her primary care physician noted that her potassium has been persistently low despite potassium supplementation.
Demographics
- Age: 38 years
- Sex: Female
- Past Medical History: Hypertension diagnosed at age 32 (young-onset)
- Medications: Amlodipine 10 mg, lisinopril 40 mg, chlorthalidone 25 mg, potassium chloride 40 mEq daily
- Family History: No hypertension in immediate family
Chief Complaint
Resistant hypertension and recurrent hypokalemia despite supplementation
Physical Examination
- Blood pressure: 168/102 mmHg (despite three medications)
- Heart rate: 78 bpm
- BMI: 26 kg/m2
- General: Well-appearing
- Cardiovascular: Normal S1/S2, no murmurs
- Neurological: Proximal muscle weakness (difficulty rising from squat)
- No cushingoid features, no abdominal bruit
Workup
- Serum potassium: 2.9 mEq/L (low despite supplementation)
- Serum sodium: 144 mEq/L (high-normal)
- Plasma aldosterone concentration (PAC): 28 ng/dL (elevated)
- Plasma renin activity (PRA): 0.2 ng/mL/hr (suppressed)
- Aldosterone-to-renin ratio (ARR): 140 (elevated; >30 suggests primary aldosteronism)
- Confirmatory test: Oral sodium loading - aldosterone remains elevated (not suppressed)
- CT adrenal: 1.8 cm left adrenal adenoma, right adrenal normal
- Adrenal vein sampling: Lateralizes to left adrenal gland
Diagnosis
Primary Aldosteronism (Conn Syndrome) due to Left Adrenal Aldosterone-Producing Adenoma
Treatment
- Hold interfering medications before testing (MRA, diuretics if possible)
- Preoperative preparation:
- Spironolactone or eplerenone to control BP and correct hypokalemia
- Potassium supplementation
- Laparoscopic left adrenalectomy (curative for unilateral adenoma)
- Postoperative monitoring:
- BP typically normalizes or improves significantly
- Monitor for transient hypoaldosteronism
- Long-term: If bilateral disease or surgery not pursued, medical therapy with mineralocorticoid receptor antagonist
Physiological Principles Demonstrated
- Primary vs. secondary aldosteronism: In primary aldosteronism, the adrenal gland produces excess aldosterone autonomously. Renin is suppressed due to volume expansion and sodium retention. In secondary hyperaldosteronism (e.g., renal artery stenosis), renin is elevated.
- Aldosterone effects: Aldosterone acts on the distal nephron to promote sodium reabsorption and potassium/hydrogen secretion. Excess aldosterone causes hypertension (volume expansion) and hypokalemia.
- Resistant hypertension clues: Young onset, hypokalemia, and failure of multiple antihypertensives should raise suspicion for secondary causes.
- Aldosterone-to-renin ratio: The ARR exploits the expected reciprocal relationship between aldosterone and renin to screen for autonomous aldosterone production.