Conn’s Syndrome


Primary hyperaldosteronism /Conn’s Syndrome is an adrenal gland disorder which is characterized by overproduction of aldosterone resulting in sodium along with water retention as well as hypokalemia and metabolic alkalosis. HTN is seen in Coon’s Syndrome. Here plasma renin activity is suppressed.

Primary hyperaldosteronism /Conn's Syndrome

Etiology of Conn’s Syndrome

hyperaldosteronism mostly caused by adrenocortical adenoma or maybe other cause such as  hyperplasia of the adrenal gland, Aldosterone-producing adenomas, Aldosterone-producing renin-responsive adenomas, Bilateral idiopathic adrenal  hyperplasia, Familial forms of primary aldosteronism, Ectopic secretion of aldosterone


In the pathology of the adrenal cortex, there is present adenoma which is more commonly unilateral in nature and more commonly in the left side and more commonly solitary encapsulated lesion and this is usually less than 2 cm and this adenoma composed of uniform cortical cells filled with lipid-containing vesicles that provide appearance bright yellow tumor.

On microscopic examination, spironolactone bodies might found which are esonophililic laminated cytoplasmic inclusions which are seen after treatment with spironolactone.
In the pathology of adrenal hyperplasia, there is presence of hyperplasia of cells of  zonaglomerulosa. In 20-40 % of cases, bilateral micronodular hyperplasia is present.

Somatic mutations at the KCNJ5 been coding for potassium channel kir3.4 are present in aldosterone-producing adenomas and a germline KCNJ5 mutation can cause a very rare Autosomal Dominant and early onset from primary hyperaldosteronism in bilateral adrenal hyperplasia.

Primary hyperaldosteronism vs secondary hyperaldosteronism


Clinical features of Conn’s Syndrome

• Hypertension (HTN)

• Non-specific symptoms such as headache, muscle weakness sometimes with tetany, cramps, neurological events, polyuria, polydipsia, renal potassium wasting as well as nocturia.
Note:- No edema with Conn syndrome unlike in secondary hyperaldosteronism that is known as escape effect.

In primary aldosteronism  Diastolic HTN present and decrease renin secretion but in secondary aldosteronism diastolic HTN is absent and renin secretion is increased. This is how we can differentiate between primary and secondary hyperaldosteronism.

Diagnosis of Conn’s Syndrome

  • Assessment of the aldosterone to plasma renin activity ratio.
  • Blood test 
  • Captopril suppression test 
  • 24 hours urinary excretion of aldosterone test.
  • Saline suppression test 

Confirmatory (second-tier) include:

  • Serum aldosterone level
  • 24-hour urinary aldosterone excretion test
  • Salt-loading test

Tests for determining the primary aldosteronism subtype (Third -tier):

  • Postural stimulation test
  • Furosemide (Lasix) stimulation test
  • Diurnal rhythm of aldosterone

A. Laboratory findings 
Metabolic alkalosis which is mainly due to excessive aldosterone secretion decreases serum potassium in spite of reducing renin level.
B. Radiological findings
Once the biochemical diagnosis is confirmed, MRI or CT should be done in order to distinguish unilateral from bilateral disease. Conn’s adenomas mostly measure 1-2 cm and detected by CT with a sensitivity of 80-90%. Selective adrenal vein catheterization is done before a decision on non-surgical or surgical treatment is made in case of undiagnosed micronodular changes. During selective adrenal vein catheterization, samples are obtained from vena cava and from both adrenal veins, and then aldosterone to cortisol ratio is determined in each sample.

Treatment of Conn’s Syndrome

Pharmacological therapy include

  • Calcium channel blockers
  • Mineralocorticoid antagonists
  • Glucocorticoids

Preoperative management 
• HTN should be corrected

• Hypokalemia should be corrected with a potassium supplement or a mineralocorticoid receptor antagonist before the patient going for the operation.
First-line therapy for primary hyperaldosteronism with bilateral hyperplasia is medical treatment with spironolactone and in some cases supplemental anti – HTN medication (Calcium channel blockers) used to reduce or control high blood pressure.

Laparoscopy adrenalectomy used for patients with unilateral disease (adenoma or hyperplasia) so unilateral adrenalectomy induces a significant reduction in aldosterone secretion and correction of the hypokalemia. A subtotal adrenal resection can be done in case of a typical single Conn’s adenoma.

Surgery is the treatment of choice for the generalizable variants of primary aldosteronism, including typical aldosteronomas, renin-responsive adenomas (RRAs), and primary adrenal hyperplasia (PAH).

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