Bartter syndrome

Background

  • Bartter syndrome is a group of rare autosomal recessive renal tubular disorders causing salt wasting from the thick ascending limb of the loop of Henle, resulting in hypokalemic hypochloremic metabolic alkalosis with normal or low blood pressure[1] It mimics chronic loop diuretic use
  • The EM physician encounters Bartter syndrome as a severely dehydrated infant with refractory hypokalemia, a child with failure to thrive and electrolyte derangements, or a known patient in crisis from intercurrent illness
  • The critical EM task is to recognize the electrolyte pattern, correct life-threatening hypokalemia, and avoid attributing the findings to vomiting or diuretic abuse.
  • Incidence ~1 in 1,000,000; much rarer than Gitelman syndrome (~1 in 25,000)
  • Neonatal/antenatal Bartter: severe; presents in utero with polyhydramnios → premature birth → massive polyuria, dehydration, nephrocalcinosis within first weeks of life
  • Classic Bartter: presents in infancy to school age with polyuria, polydipsia, failure to thrive, growth retardation
  • Biochemically mimics chronic furosemide use — the transporter affected (NKCC2) is the same target as loop diuretics[1]
  • Pseudo-Bartter syndrome can occur in cystic fibrosis (salt loss in sweat), chronic vomiting, or diuretic abuse — must be excluded

Clinical Features

  • Polyuria and polydipsia (often severe; neonates may lose >10% body weight in first days)
  • Dehydration — may be profound, especially with intercurrent illness (vomiting, diarrhea, fever)
  • Failure to thrive, growth retardation
  • Muscle weakness, cramps, fatigue (from hypokalemia)
  • Constipation (from hypokalemia)
  • Cardiac arrhythmias — potentially fatal; from severe hypokalemia ± hypomagnesemia; cardiac arrest has been reported[2]
  • Normal or low blood pressure despite high renin/aldosterone (distinguishes from other causes of hyperaldosteronism)
  • Neonatal Bartter: history of polyhydramnios and premature birth
  • Some subtypes: sensorineural deafness (type IV)
  • Dysmorphic facies in some neonatal cases: triangular face, protruding ears, large eyes

Differential Diagnosis

  • Gitelman syndrome: the most important differential — milder, presents later (adolescence/adulthood), has hypocalciuria and hypomagnesemia (Bartter has hypercalciuria and usually normal magnesium); mimics thiazide diuretic use rather than loop diuretic use
Feature Bartter syndrome Gitelman syndrome
Mimics Loop diuretic (furosemide) Thiazide diuretic (HCTZ)
Onset Infancy/childhood (often neonatal) Adolescence/adulthood
Severity More severe; life-threatening dehydration Milder; often incidental finding
Urine calcium High (hypercalciuria → nephrocalcinosis) Low (hypocalciuria)
Magnesium Usually normal Low (hypomagnesemia)
  • Surreptitious vomiting / bulimia: urine chloride <25 mEq/L (Bartter: urine chloride >35 mEq/L) — this is the key distinguishing test
  • Diuretic abuse: screen urine for diuretics
  • Congenital adrenal hyperplasia (neonatal salt-wasting form) — hyperkalemia with salt wasting (opposite potassium direction from Bartter)
  • Cystic fibrosis (pseudo-Bartter from sweat salt loss) — sweat chloride test
  • Chronic laxative abuse
  • Primary hyperaldosteronism — hypertension present (Bartter is normotensive/hypotensive)

Hypokalemia

Metabolic alkalosis

Renal tubular disorders

  • Salt-wasting tubulopathies
    • Gitelman syndrome — distal convoluted tubule (NCC defect); hypokalemia, hypomagnesemia, hypocalciuria, metabolic alkalosis
    • Bartter syndrome — thick ascending limb (NKCC2/ROMK/ClC-Kb defect); hypokalemia, hypercalciuria, metabolic alkalosis
    • Liddle syndrome — collecting duct (ENaC gain-of-function); hypokalemia, hypertension, metabolic alkalosis
  • Renal tubular acidosis
  • Inherited disorders of tubular transport
    • Cystinuria — proximal tubule amino acid transport defect; recurrent cystine stones
    • Fanconi syndrome — proximal tubule generalized dysfunction; glucosuria, aminoaciduria, phosphaturia
    • Nephrogenic diabetes insipidus — collecting duct (aquaporin/V2R defect); polyuria, hypernatremia
    • Dent disease — proximal tubule (ClC-5 defect); low molecular weight proteinuria, nephrocalcinosis
  • Acquired tubulopathies

Evaluation

Workup

  • BMP: hypokalemia (may be severe, <2.5 mEq/L), hypochloremia, metabolic alkalosis (elevated bicarbonate), normal or low sodium
  • Magnesium: normal in most Bartter (low suggests Gitelman or type III Bartter)
  • ABG/VBG: metabolic alkalosis
  • Urine electrolytes:
    • Urine chloride >35 mEq/L — confirms renal salt wasting (NOT vomiting)
    • Urine potassium elevated — inappropriate renal potassium wasting
    • Urine calcium:creatinine ratio elevated — hypercalciuria (classic Bartter); LOW in Gitelman
  • Renin and aldosterone: both elevated (secondary hyperaldosteronism) — but blood pressure is not elevated
  • ECG: assess for hypokalemia changes (flattened T waves, U waves, ST depression, prolonged QT, arrhythmias)
  • Renal ultrasound: nephrocalcinosis (especially neonatal Bartter types I and II)

Diagnosis

  • Hypokalemic hypochloremic metabolic alkalosis + elevated urine chloride (>35) + normal/low blood pressure + elevated renin/aldosterone = Bartter syndrome pattern
  • Exclude vomiting (urine Cl <25), diuretic abuse (urine drug screen), and laxative abuse
  • Genetic testing (SLC12A1, KCNJ1, CLCNKB, BSND, CASR) confirms subtype — not an ED test
  • The diagnosis is clinical and biochemical — genetic confirmation follows

Management

  • Correct hypokalemia — this is the EM priority
    • IV potassium chloride for severe hypokalemia (K <2.5 mEq/L) or ECG changes or arrhythmias — use KCl, not other potassium salts (the chloride is needed to correct the concurrent hypochloremia and alkalosis)
    • Oral potassium supplementation for mild-moderate hypokalemia
    • Potassium replacement may be massive — these patients have ongoing renal losses; expect to give more than typical and monitor closely
    • Correct hypomagnesemia if present (magnesium deficiency causes refractory hypokalemia)
  • Aggressive IV fluid resuscitation with normal saline for dehydration — these patients are volume-depleted from renal salt wasting
  • Cardiac monitoring — continuous telemetry if K <3.0 mEq/L or any ECG changes
  • Continue home medications if the patient takes indomethacin, potassium supplements, or spironolactone — do NOT discontinue these
  • Treat precipitating illness: intercurrent infection, GI illness, or any condition that worsens salt/water losses can precipitate acute crisis
  • Do NOT use loop diuretics (furosemide) — this worsens the underlying defect
  • Perioperative alert: patients with Bartter syndrome require careful electrolyte monitoring and IV potassium during surgery/anesthesia; alert anesthesia team if the patient presents for a procedure

Disposition

  • Admit:
    • Severe hypokalemia (K <2.5 mEq/L) or ECG changes/arrhythmias
    • Severe dehydration requiring IV resuscitation
    • Neonatal presentation (needs NICU; nephrology consultation)
    • Unable to tolerate oral fluids and medications
  • Discharge with close follow-up:
    • Mild-moderate hypokalemia corrected with oral supplementation
    • Tolerating PO fluids and home medications
    • Stable hemodynamics
    • Pediatric nephrology follow-up within days
  • New diagnosis suspected (unexplained hypokalemic metabolic alkalosis in a young patient with renal potassium/chloride wasting and normal BP): arrange nephrology referral for confirmatory workup
  • Counsel families: aggressive oral hydration is critical (especially during illness, hot weather, exercise); report symptoms of hypokalemia (weakness, cramps, palpitations, fainting) immediately

See Also

External Links

References

  1. ↑ 1.0 1.1 Bartter Syndrome. StatPearls
    • NCBI. 2026.
  2. ↑ Konrad M, et al. Diagnosis and management of Bartter syndrome: consensus from ERKNet. Kidney Int. 2021;99(2):324-338.
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