Apparent Mineralocorticoid Excess Syndrome :‎ Medical Notes & Mindmap

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Apparent mineralocorticoid excess (AME) syndrome is a rare genetic disorder characterised by excessive aldosterone production, a hormone that regulates electrolyte balance and blood pressure.

Excess aldosterone causes high sodium and low potassium levels in the blood, which can lead to a variety of health problems such as hypertension, hypokalemia, metabolic alkalosis, and heart arrhythmias.

Apparent Mineralocorticoid Excess Syndrome :‎ [MEDNOTES+MINDMAP]

 

  • Definition
    • A rare disorder caused by mutations in the gene for 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2)
    • Results in overproduction of the mineralocorticoid hormone, deoxycorticosterone (DOC)
    • Can lead to hypertension and hypokalemia, as well as other symptoms such as edema, headaches, and muscle weakness
  • Epidemiology
    • Estimated incidence of 1 in 1,000,000
    • More common in males than females
    • Can occur in all ethnicities
  • Natural history
    • Symptoms typically begin in early childhood
    • If left untreated, can lead to complications such as cardiovascular disease and end-organ damage (e.g. kidney damage)
    • Can be effectively treated with mineralocorticoid receptor antagonists, such as spironolactone
  • Classification
    • Classic AME: caused by mutations in the HSD11B2 gene, results in overproduction of DOC
    • Non-classic AME: caused by mutations in other genes, results in overproduction of other mineralocorticoids
    • Mild, moderate, or severe depending on the level of mineralocorticoid hormone production and symptoms

  • Risk Factors

    • Familial
    • Genetic mutations in enzymes involved in mineralocorticoid metabolism (11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), aldosterone synthase (CYP11B2), and mineralocorticoid receptor)
    • Drug-induced (licorice, carbenoxolone, metyrapone)

  • Etiology/Causes

    • Defect in 11beta-HSD2 enzyme, leading to increased conversion of cortisone to cortisol and increased mineralocorticoid activity
    • Mutations in CYP11B2 enzyme, leading to increased aldosterone production
    • Mutations in mineralocorticoid receptor, leading to increased sensitivity to mineralocorticoids

  • Signs

    • Hypertension
    • Hyperkalemia
    • Metabolic alkalosis
    • Hypokalemic alkalosis

  • Symptoms

    • Fatigue
    • Weakness
    • Muscle cramps
    • Nausea
    • Polyuria

  • Pathology/Pathogenesis

    • Excess mineralocorticoid activity leads to increased sodium retention and potassium excretion by the kidneys, leading to hypertension and hyperkalemia
    • Increased aldosterone production also leads to increased secretion of hydrogen ions in the distal tubules, leading to metabolic alkalosis.
    • Low potassium levels in the body lead to increased secretion of hydrogen ions by the kidneys, leading to hypokalemic alkalosis.
    • Progressive damage to the kidneys and other organs can occur due to chronic hypertension and electrolyte imbalances.
  • Diagnosis
    • Elevated levels of plasma renin activity (PRA) and aldosterone
    • Low serum potassium levels
    • High blood pressure
  • Tests Required
      • Plasma renin activity test
      • Aldosterone-to-renin ratio test
      • Serum potassium levels test
      • Blood pressure test
  • Associated with
        • 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) deficiency
        • Liddle’s syndrome
  • Similar diseases/syndromes
    • Conn’s syndrome
    • Bartter’s syndrome
    • Gitelman’s syndrome Treatment
    • Surgery (for Liddle’s syndrome)

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Dr. Arin Nandi

Passionate About Medical Science & Helping Future Doctors Achieve Top Ranks In Medical Exams. He is professionally a dentist as well as a public health expert from JIPMER working in govt.health department
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