Bartter Syndrome

Snapshot

A 3-year-old boy is brought to the pediatrician due poor growth and increased urinary frequency. According to the mother, the child appears to be very thirsty. He was born prematurely and the mother states she was found to have polyhydramnios on ultrasonograpahy while pregnant. Laboratory testing is significant for hypokalemia, hypochloremia, mild hypomagnesemia, and metabolic alkalosis.

Introduction

Clinical definition
- a renal tubular disorder characterized by
  - hypokalemia
  - hypochloremia
  - metabolic alkalosis
  - normotension
  - elevated plasma renin level
Epidemiology
- incidence
  - rare
  - precise incidence is unknown
- demographics
  - neonatal cases
    - can be suspected before birth and diagnosed soon after birth
  - classic cases
    - begins around 2 years of age or younger
  - no race or sex predilection
- risk factors
  - family history
Pathophysiology
- pathobiology
  - mutation involving the Na⁺/K⁺/Cl^– cotransporter (NKCC2) results in salt and water loss resulting in
    - activation of the renin-angiotensin-aldosterone system secondary to volume depletion
    - renal vasoconstriction due to angiotensin II and hypokalemia leads to an increase in prostaglandin E (PGE)
Genetics
- inheritance pattern
  - autosomal recessive
Prognosis
can slowly progress to interstitial fibrosis resulting in chronic renal failure

Presentation

Studies

Labs
- ↑ plasma renin and aldosterone
- ↓ serum potassium and chloride
- ↑ urine prostaglandin E
genetic testing

Differential

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 diseaseTyrosinemiaCystinosisMultiple myelomaGalactosemiaMitochondrial myopathiesMedicationsaminoglycosidescisplatinifosfamidevalproic acidHeavy metalsmercury lead	Autosomal recessive mutation involving the NKCC2 cotransporter	Autosomal recessive mutation involving the Na⁺Cl^– cotransporter	Autosomal dominant mutation leading to increased activity of epithelial sodium channel (ENaC)
Findings	HypophosphatemiaAminoaciduriaRenal glucosuriaTubular proteinuriaProximal renal tubular acidosis	HypokalemiaHypochloremiaMetabolic alkalosisNormotensionElevated plasma renin level	HypokalemiaHypochloremiaMetabolic alkalosisHypomagnesemiaHypocalciuriaNormotension	HypertensionHypokalemiaMetabolic alkalosis

Treatment

Complications

Complications