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Gitelman Syndrome

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Topic updated on 08/31/17 10:40pm

Snapshot
  • An 8-year-old girl is brought to the pediatrician for evaluation of increased urinary frequency. She has muscle cramps and fatigue. She is found to be normotensive. Laboratory exam reveals hypomagnesemia, hypokalemia, and a mild metabolic alkalosis.
Introduction

  • Clinical definition
    • a renal tubular defect affecting the distal convoluted tubules characterized by
      • mild hypokalemia
      • mild metabolic alkalosis
      • significant hypomagnesemia
      • normal blood pressure
  • Epidemiology
    • incidence
      • rare
      • 1:40,000
    • demographics
      • detected in young children but can be detected in adulthood
    • risk factors
      • consanguinity
  • Pathogenesis
    • mutation involving NaCl cotransporter (NCTT) which results in
      • impaired Na+ reabsorption in distal convoluted tubule
  • Genetics
    • inheritance pattern
      • autosomal recessive
    • mutations
      • chromosome
      • SLC12A3 gene
Presentation
  • Symptoms
    • polyuria
    • polydipsia
    • muscle weakness or cramp
    • fatigue
    • paresthesias
    • abdominal pain
    • vomiting
  • Physical exam
    • growth is often normal but can be delayed
Studies
  • Labs
    • hypokalemia (lower than in Bartter’s)
    • hypomagnesemia
    • metabolic alkalosis
    • genetic testing
      • most definitive diagnosis
  • Urine studies
    • ↓ Ca2+
Differential
  • Bartter’s syndrome
    • normal serum magnesium
 
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 epithelial Na+ channel (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
  • Conservative
    • optimize electrolytes with diet or supplements
      • indications
        • those with hypokalemia or hypomagnesemia
  • Medical
    • nonsteroidal anti-inflammatory drugs (NSAIDs)
      • indications
        • for patients who require medical therapy beyond dietary supplements
      • drugs
        • indomethacin
        • celecoxib
    • potassium-sparing diuretics
      • indications
        • to treat hypokalemia and metabolic alkalosis
      • drugs
        • amiloride
        • eplerenone
Complications
  • Cardiac arrhythmia due to hypomagnesemia and hypokalemia
  • Chondrocalcinosis


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