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Liddle Syndrome

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Topic updated on 08/31/17 10:39pm

Snapshot
  • A 12-year-old girl is brought to the emergency department due to nausea and vomiting over the course of a few days. Her blood pressure is 140/103 mmHg. Laboratory testing is significant for hypokalemia, metabolic alkalosis, and undetectable levels of renin and aldosterone.
Introduction
 

 
  • Clinical definition
    • a renal tubular disorder affecting the collecting tubules characterized by
      • hypertension
      • hypokalemia
      • metabolic alkalosis
    • also known as pseudohyperaldosteronism
  • Epidemiology
    • incidence
      • rare
    • demographics
      • young children
        • suspected if there is early onset hypertension
      • may not be detected until adulthood
    • risk factors
      • family history of early onset hypertension or hypokalemia may suggest Liddle’s
  • Pathogenesis
    • gain of function mutation involving the epithelial Na+ channel (ENaC) resulting in
      • increased Na+ reabsorption in the collecting tubules
        • this causes the lumen to be electronegative and causes a gradient that favors secretion of K+ into the lumen
          • this results in decreased K+
      • mimics hyperaldosteronism (recall that aldosterone increases the number of open luminal Na+ channels)
  • Genetics
    • inheritance pattern
      • autosomal dominant
    • mutations
      • chromosome 16p12
  • Prognosis
    • very good with treatment
Presentation
  • Symptoms
    • triad presenting at a young age
      • hypertension
      • hypokalemia
      • metabolic alkalosis
  • Physical exam
    • hypertension
Studies
  • Labs
    • hypokalemia
    • metabolic alkalosis
    • ↓ aldosterone
    • ↓ renin
    • genetic testing
      • most definitive diagnosis
Differential
  • Primary hyperaldosteronism
  • Congenital adrenal hyperplasia
 
Renal Tubular Defects
Category
Fanconi Syndrome
Bartter Syndrome Gitelman Syndrome Liddle Syndrome
Defect localization
  • Proximal tubule
  • Thick ascending loop of Henle
  • Distal convoluted tubule   
  • Collecting tubule      
Etiology
  • Wilson disease
  • Tyrosinemia
  • Cystinosis
  • Multiple myeloma
  • Galactosemia
  • Mitochondrial myopathies
  • Medications
    • aminoglycosides
    • cisplatin
    • ifosfamide
    • valproic acid
  • Heavy metals
    • mercury
    • lead
  • Autosomal recessive mutation involving the NKCC2 cotransporter
  • Autosomal recessive mutation involving the NaCl cotransporter
  • Autosomal dominant mutation leading to increased activity of ENaC
Findings
  • Hypophosphatemia
  • Aminoaciduria
  • Renal glucosuria
  • Tubular proteinuria
  • Proximal renal tubular acidosis
  • Hypokalemia
  • Hypochloremia
  • Metabolic alkalosis
  • Normotension
  • Elevated plasma renin level
  • Hypokalemia
  • Hypochloremia
  • Metabolic alkalosis
  • Hypomagnesemia
  • Hypocalciuria
  • Normotension
  • Hypertension
  • Hypokalemia
  • Metabolic alkalosis
 
Treatment
  • Medical
    • potassium-sparing diuretics
      • indication
        • for all with Liddle syndrome
        • recall that both drugs directly blocks Na+ channels in the collecting tubules
      • drugs
        • amiloride
        • triamterene
Complications
  • Cardiac arrhythmia due to hypokalemia  


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