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Symptoms and Treatment of Hyperaldosteronism and Conn Syndrome

Definition and Etiology

Hyperaldosteronism is a symptom complex triggered by an excess of aldosterone.

• Primary hyperaldosteronism: without activation of the renin-angiotensin-aldosterone system (RAAS).
  • Adrenal adenoma (Conn syndrome).
  • Adrenocortical carcinoma.
  • Bilateral hyperplasia of the zona glomerulosa
• Secondary hyperaldosteronism: with activation of the RAAS.
  • With hypertension: renal hypertension, reninsecreting tumor, pheochromocytoma, hypertension treated with diuretics.
  • Loss of extracellular volume: nephrotic syndrome, tubular nephropathies, Bartter syndrome, edema.
  • Reduced aldosterone metabolism in hepatic insufficiency.
  • Others: laxative abuse, estrogen therapy, anorexia nervosa.

Pathophysiology of Hyperaldosteronism

The excess of aldosterone leads to the upregulation and activation of the basolateral Na/K pump, which in turn leads to increased sodium reabsorption and potassium excretion in the distal tubule and collecting tube. The increased sodium reabsorption is compensated elsewhere in the nephron, preventing relevant hypernatremia (renal escape). No comparable mechanism exists for potassium secretion and hypokalemia and alkalosis results. Avoiding sodium (table salt) leads to a reduction in renal compensation and, thus, a decrease in potassium loss.

Signs and Symptoms of Hyperaldosteronism

• Arterial hypertension.
• Hypokalemia: paresthesias, muscle weakness, polyuria, nocturia, reversible paralysis.

Diagnosis

Before starting the diagnostic tests, recommend a high-salt diet and stop antihypertensives and spironolactone for two weeks.

Laboratory Tests

• Serum potassium: hypokalemia, serum concentrations >3.6 mmol/l make primary hyperaldosteronism unlikely.
• Serum aldosterone: elevated, normal value lying after two hours of strict bed rest (depending on laboratory): 25–450 pmol/l (20–100 ng/ml).
• 24-hour urine collection: aldosterone concentrations on a high salt diet are normally <10 μg, values above 25 μg are suspicious for hyperaldosteronism. In addition, increased potassium excretion is found.
• Aldosterone/renin ratio: both in ng/l: >20 indicates primary hyperaldosteronism.
• Saline infusion test: aldosterone is measured before and after infusion of 2 liter NaCl 0.9% over 4 hours; aldosterone values above 5 ng/dl after saline infusion indicate hyperaldosteronism.

Abdominal CT or MRI:

Imaging is indicated for patients with primary hyperaldosteronism to differentiate between adenoma, carcinoma, or bilateral adrenocortical hyperplasia.

Adrenal venous sampling:

For patients with primary hyperaldosteronism, blood samples are taken from both adrenal veins to determine the localization of the aldosterone production before surgery.

Treatment of Hyperaldosteronism

Spironolactone is an aldosterone receptor antagonist. Spironolactone is indicated in bilateral adrenocortical hyperplasia without lateralization. Otherwise, spironolactone is used in combination therapy for arterial hypertension.

Adrenalectomy is an option for patients with unilateral aldosterone secretion (adenoma or carcinoma) but also in cases of predominantly unilateral aldosterone secretion in bilateral adrenocortical hyperplasia. Arterial hypertension may persist in 30% despite surgery (Suurd et al., 2021).

References

Ganguly 1998 GANGULY, A.: Primary aldosteronism.
In: N Engl J Med
339 (1998), Nr. 25, S. 1828–34

  Deutsche Version: Conn-Syndrom und Hyperaldosteronismus