Hyperaldosteronism 

(Conn’s syndrome – both hyper-secretions are “C” diseases – cf. Cushing’s)

• Caused by Inappropriate Aldosterone Hypersecretion
• Represents under 6% of Hypertension Causes
• Most common cause of drug Resistant Hypertension
• Peak age 30-50 years
• More common in women
• carry a higher risk of cardiovascular complications including stroke, atrial fibrillation, coronary artery disease and heart failure when compared with patients with blood pressure–matched essential hypertension (due to the deleterious effects of aldosterone)

Causes: 

• Primary Hyperaldosteronism (Conn’s Disease)
  • Solitary Adrenal Adenomas (80-90%)
  • Bilateral adrenal hyperplasia (10-20%)
    • Idiopathic Hyperaldosteronism
    • Accounts for 50% of cases at some referral centers
  • Adrenal Carcinoma (rare)
  • Unilateral Adrenal Hyperplasia (very rare)

• Secondary Hyperaldosteronism
  • Hypertensive States
    • Primary Reninism (rare renin producing tumor)
    • Secondary reninism due to decreased renal perfusion
  • Edematous States
    • Cirrhosis
    • Nephrotic Syndrome
  • Excessive Growth Hormone (Acromegaly)

• Primary Hyperaldosteronism 🡪 Increased Aldosterone is initiating event
  • Results in Sodium retention and volume increase
  • Renin decreases
• Secondary Hyperaldosteronism 🡪 Decreased circulating volume is initiating event
  • Results in increased renin and Aldosterone
  • Results in Sodium retention
• first described by Conn in 1954

clinical features:

• Often Asymptomatic
• Hypertension
  • May be severe
  • Rarely malignant
• Frontal Headache
• Muscle Weakness to Flaccid Paralysis (Hypokalemia)
• Polyuria and Polydipsia (Carbohydrate intolerance)

Differentials for Hypertension with Hypokalemia

• Cushing’s Disease: Low Aldosterone and Low Plasma Renin
• Renal Artery Stenosis or other renal cause: High Aldosterone and High Plasma Renin

Labs

• Hypokalemia
  • is the most prominent feature of Hyperaldosteronism
  • However, Potassium is normal in 50% of Hyperaldosteronism causes
• Serum Sodium increased (Mild)
• Metabolic Alkalosis
• Morning Aldosterone to aldosterone-to-renin ratio (ARR)
  • ARR is a screening rather than diagnostic test and can be affected by many commonly used antihpertensive medications, so patients should ideally cease medication or switched to non-interfering antihypertensives prior to testing
  • Ratio over 20-25 (esp if >100) suggests Hyperaldosteronism
  • Aldosterone >15 ng/dl and plasma renin low
    • Serum Aldosterone alone may be normal in 25% of Hyperaldosteronism patients

Factors affecting the aldosterone-to-renin ratio (ARR)
Causes of false-positive ARR	Beta-blocker Central agonists (clonidine, α-methyldopa) Nonsteroidal anti-inflammatory drugs Licorice Renal impairment Oral oestrogens
Causes of false-negative ARR	Diuretics Dihydropyridine calcium channel blockers Angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers Hypokalaemia Dietary salt restriction Renovascular disease Pregnancy
Antihypertensive medications that are less likely to interfere with ARR	Sustained-release verapamil Moxonidine Prazosin Hydralazine

Treatment:

• Adrenal Adenoma: Surgical excision
• Adrenal Hyperplasia
  • Spironolactone (S/E: Gynecomastia