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Primary Hyperaldosteronism             

Title               

Ñ    Primary Hyperaldosteronism        

Definition

Ñ    Excess production of aldosterone

Ñ    Independent of the renin-angiotensin axis

Pathogenesis

Ñ    Adrenal adenoma:

Conn’s syndrome

Ñ    Bilateral adrenal hyperplasia

Ñ    Adrenal carcinoma:

Rare

Ñ    Glucocorticoid-remediable aldosteronism (GRA):

Condition where aldosterone production is under the control of ACTH

Pathophysiology

Ñ    Increased physiological effects of aldosterone

Clinical Features

History

Ñ    Adenoma:

More common in young females

Ñ    Bilateral adrenal hyperplasia:

Rare under the age of 40 years

More common in males

KUS

Ñ    Nocturia

CNS

Ñ    Muscle weakness

Ñ    Tetany

Examination

CVS

Ñ    Hypertension

Investigations

The objectives of investigation are:

Ñ    Establish diagnosis

Ñ    Differentiate cause

Establish Diagnosis

Fluids

Blood

Biochemistry

Ñ    Hypokalaemic alkalosis

Ñ    Increased aldosterone: plasma renin activity ratio

Urine

Ñ    Potassium loss:

> 30 mmol/day in the presence of hypokalaemia

Differentiate cause

Adenoma or hyperplasia:

Fluids

Blood

Biochemistry

Ñ    Selective venous catheterisation for aldosterone levels

Ñ    18-OH cortisol:

Increased in adenoma

Ñ    0800 supine, 1200 erect blood levels of aldosterone, cortisol:

·          In normal people aldosterone levels rise when they are erect and the 1200 level is approximately twice 0800 level

·          This response is seen in adrenal hyperplasia

·          In adenoma and GRA aldosterone is under the control of ACTH and hence levels fall:

Rare exception is angiotensin II sensitive adenoma

Ñ    Overnight dexamethasone suppression test:

Suppresses aldosterone production in GRA

Imaging

CT or MRI

Ñ    May miss small tumours

Nuclear Medicine

Adrenal scintigraphy

Ñ    Unilateral or bilateral uptake

Management

Control

Drugs

Ñ    Spironolactone

Ñ    Amiloride

Ñ    Dexamethasone:

For GRA

Surgery

Ñ    Adenoma

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