Updated: 6/22/2018

Syndrome of Apparent Mineralocorticoid Excess (SAME)

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Snapshot
  • A 1-year-old girl is brought to the pediatrician’s office for failure to thrive and muscle weakness. Her parents deny any problems with feeding. On physical exam, her blood pressure is elevated for her age. Laboratory tests reveal hypokalemia, metabolic alkalosis, and low serum aldosterone and renin.
Introduction
 

 
  • Clinical definition
    • Syndrome of Apparent Mineralocorticoid Excess (SAME) is a hereditary defect in 11β-hydroxysteroid dehydrogenase causing
      • hypertension
      • hypokalemia
      • metabolic alkalosis
    • these findings are similar to those in primary aldosteronism
  • Epidemiology
    • demographics
      • early childhood onset
    • risk factors
      • family history
  • Etiology
    • hereditary deficiency
    • acquired disorder
      • ingestion of glycyrrhetinic acid (licorice)
  • Pathogenesis
    • genetic loss-of-function mutation in 11β-hydroxysteroid dehydrogenase (kidney isoform)
      • 11β-hydroxysteroid dehydrogenase usually converts cortisOL to cortisONE
        • cortisOL can activate mineralocorticoid receptors (with similar affinity with aldosterone)
        • cortisone is inactive
      • deficiency results in excess cortisol
        • this will increase activation of mineralocorticoid receptor
    • glycyrrhetinic acid inhibits 11β-hydroxysteroid dehydrogenase and reduces gene expression
  • Genetics
    • inheritance pattern
      • autosomal recessive
    • mutations
      • chromosome 16
      • 11β-HSD2 gene
Presentation
  • Symptoms
    • infants
      • low birth weight
      • failure to thrive
  • Physical exam
    • muscle weakness due to hypokalemia
    • hypertension
Studies
  • Labs
    • hypokalemia
    • metabolic alkalosis
    • ↓ aldolsterone level
    • ↓ renin activity
    • may have ↑ creatinine
  • Urine
    • hypercalciuria
    • free cortisol to free cortisone ratio on 24-hour urine collection
Differential
  • Liddle syndrome
    • urine cortisol to cortisone ratio is normal
  • Primary aldosteronism
    • elevated aldosterone
Treatment
  • Conservative
    • remove licorice from diet
      • indications
        • for those with acquired SAME from licorice ingestion
  • Medical
    • mineralocorticoid receptor blockade
      • indications
        • for those with hereditary SAME
      • drugs
        • spironolactone
        • eplerenone
        • amiloride
        • triamterene
    • corticosteroids
      • indications
        • if mineralocorticoid blockade is not effective or tolerated
    • thiazides
      • indications
        • hypercalciuria
Complications
  • Cardiac arrhythmia from hypokalemia
  • Nephrocalcinosis

References

 

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