BARTTER SYNDROME

✓ Medically ReviewedDISEASEID: MDBT0255🚨 TRIAGE: URGENTICD-10: E26.8

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Definition

CLINICAL DEFINITION

Bartter syndrome is a rare, autosomal recessive renal tubular disorder characterised by impaired salt reabsorption in the thick ascending limb of the loop of Henle, leading to hypokalaemic, hypochloraemic metabolic alkalosis with secondary hyperaldosteronism and normal to low blood pressure. It encompasses a group of genetically heterogeneous tubulopathies typically presenting with polyuria, polydipsia, and varying degrees of salt wasting, growth retardation, and hypercalciuria.

IN PLAIN ENGLISH

Bartter syndrome is a rare inherited kidney condition where the kidneys cannot properly reabsorb salt and other minerals, causing the body to lose too much sodium, potassium, and chloride in the urine. This leads to low blood pressure, dehydration, and muscle weakness, requiring lifelong salt and mineral supplements to manage.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

Bartter syndrome is NOT Gitelman syndrome; although both cause hypokalaemic metabolic alkalosis, Bartter syndrome primarily affects the thick ascending limb of the loop of Henle (often with hypercalciuria and early onset), whereas Gitelman syndrome affects the distal convoluted tubule (typically presenting with hypocalciuria, hypomagnesaemia, and later onset). It is also NOT primary hyperaldosteronism (Conn's syndrome), as Bartter syndrome features normal or low blood pressure and secondary, rather than primary, aldosterone elevation.

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Word Breakdown

Bartter

=Named after Frederic Bartter (1920–1989), an American endocrinologist who first described the condition in 1962

syndrome

=a group of symptoms and signs that occur together and characterise a particular abnormality (from Greek 'syndrome', the concurrence of symptoms)

Literal Meaning: A collection of symptoms and signs associated with Frederic Bartter's description

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Synonyms & Variants

Bartter's Syndrome›Juxtaglomerular Hyperplasia›Antenatal Bartter Syndrome›Classic Bartter Syndrome›

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Category-Specific Context

As a genetic disease, Bartter syndrome represents a spectrum of autosomal recessive salt-wasting tubulopathies classified by the specific defective ion transporter in the thick ascending limb of the loop of Henle. Clinically, it is divided into antenatal (types 1, 2, and 5) and classic (type 3) forms based on the age of onset, severity of polyuria, and presence of nephrocalcinosis.

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Clinical Context & Usage

CLINICAL SETTINGS

Paediatric Nephrology ClinicNeonatal Intensive Care UnitEndocrinology WardGeneral Paediatrics WardAdult Nephrology Clinic

USAGE & DOCUMENTATION NOTES

In clinical documentation, it is frequently abbreviated as BS, though this can be confused with 'bowel sounds' or 'breath sounds' in other contexts, so 'Bartter syndrome' is preferred in formal notes. Clinicians often document the specific subtype (e.g., 'Classic Bartter syndrome type III') once genetic testing confirms the mutated gene (e.g., CLCNKB). Notes typically track serial electrolytes, urinary calcium-to-creatinine ratios, and growth percentiles.

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Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

Bartter syndrome arises from loss-of-function mutations in genes encoding ion transporters or channels in the thick ascending limb (TAL) of the loop of Henle, such as the Na-K-2Cl cotransporter (NKCC2), the ROMK potassium channel, or the ClC-Kb chloride channel. This defect impairs sodium, potassium, and chloride reabsorption, leading to profound salt wasting, extracellular fluid volume depletion, and activation of the renin-angiotensin-aldosterone system (RAAS). The resulting secondary hyperaldosteronism drives excessive potassium and hydrogen ion secretion in the collecting duct, producing hypokalaemic metabolic alkalosis. Furthermore, the impaired positive transepithelial voltage in the TAL reduces paracellular calcium and magnesium reabsorption, leading to hypercalciuria, which frequently causes nephrocalcinosis in antenatal forms. Elevated prostaglandin E2 (PGE2) production is a secondary consequence of the salt wasting and volume depletion, further exacerbating polyuria and renin release.

PRIMARY CAUSES

SLC12A1 gene mutation (Type I)

Loss-of-function mutation in the gene encoding the apical Na-K-2Cl cotransporter (NKCC2) in the thick ascending limb, causing severe antenatal salt wasting.

KCNJ1 gene mutation (Type II)

Mutation in the gene encoding the renal outer medullary potassium (ROMK) channel, preventing potassium recycling necessary for NKCC2 function, leading to severe antenatal Bartter syndrome.

CLCNKB gene mutation (Type III / Classic)

Loss-of-function mutation in the basolateral ClC-Kb chloride channel, impairing chloride exit from the TAL cell; presents with a more variable, often milder 'classic' phenotype.

BSND gene mutation (Type IV)

Mutation in barttin, an essential beta-subunit for ClC-Ka and ClC-Kb channels; causes Bartter syndrome with sensorineural deafness due to channel dysfunction in both the kidney and inner ear.

CASR gene gain-of-function mutation (Type V)

Activating mutation of the calcium-sensing receptor inhibiting ROMK and NKCC2 channels, causing hypocalcaemic hypercalciuria with Bartter-like features and hypoparathyroidism.

MAGED2 gene mutation (Transient Antenatal)

X-linked mutation impairing cAMP-mediated trafficking of TAL transporters, causing severe polyhydramnios and salt wasting that typically resolves spontaneously postnatally.

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Epidemiology

Prevalence:The estimated prevalence of Bartter syndrome is approximately 1 in 1,000,000 individuals globally, making it significantly rarer than Gitelman syndrome. Annual incidence in European populations is estimated at 1.2 per million live births.

Age Group:Antenatal and neonatal periods (Types I, II, IV, V present with polyhydramnios, premature birth, and severe failure to thrive); infancy and early childhood (Type III / Classic Bartter syndrome often presents later with milder symptoms, sometimes remaining undiagnosed until adulthood).

Sex Predilection:Equal

Geographic Distribution:Globally distributed with no specific ethnic predilection, though higher incidences of specific founder mutations have been reported in isolated populations, such as specific CLCNKB mutations in certain European cohorts and SLC12A1 mutations in specific consanguineous communities.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 URGENT

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Unexplained hypokalaemic metabolic alkalosis in a normotensive child — raises strong suspicion for Bartter or Gitelman syndrome; requires urgent electrolyte correction and urine chloride measurement to differentiate from vomiting or diuretic abuse
Polyhydramnios with premature delivery and neonatal polyuria — suggests antenatal Bartter syndrome; requires immediate neonatal fluid and electrolyte resuscitation to prevent fatal dehydration

URGENT EVALUATION TRIGGERS

Severe symptomatic hypokalaemia (< 2.5 mmol/L) or cardiac arrhythmias — requires immediate intravenous potassium replacement with cardiac monitoring
Profound dehydration with haemodynamic instability or acute kidney injury — requires urgent intravenous isotonic fluid resuscitation
New-onset sensorineural hearing loss or visual changes — requires urgent audiology and ophthalmology evaluation to assess for syndromic tubulopathies

Contraindications & Precautions

CONTRAINDICATIONS

Potassium-sparing diuretics without monitoring — while sometimes used
they must be carefully titrated to avoid severe hyperkalaemia if renal function declines
ACE inhibitors or ARBs in pregnancy — contraindicated due to fetal renal toxicity
despite their theoretical use in blocking secondary hyperaldosteronism
High-dose loop or thiazide diuretics — strictly contraindicated as they exacerbate the underlying tubular salt-wasting defect and worsen volume depletion

SPECIAL PRECAUTIONS

NSAID use requires monitoring of renal function and gastrointestinal tolerance
as chronic indometacin therapy can cause nephrotoxicity or peptic ulcer disease
Pregnancy in Bartter syndrome patients requires multidisciplinary high-risk obstetric care due to risks of severe polyhydramnios
premature labour
and maternal electrolyte derangement
Regular audiometry is required for patients with Type IV Bartter syndrome or those on long-term aminoglycosides to monitor for sensorineural hearing loss

Complications

DOWNSTREAM CLINICAL COMPLICATIONS

Nephrocalcinosis and nephrolithiasis — chronic hypercalciuria leads to calcium phosphate deposition in the renal parenchyma
particularly in antenatal types
Growth retardation and short stature — chronic volume depletion
electrolyte imbalances
and high metabolic demand from secondary hyperaldosteronism
Sensorineural deafness — specific to Type IV Bartter syndrome due to barttin (BSND) mutation affecting inner ear chloride channels
Chronic kidney disease — progressive renal impairment can occur due to prolonged nephrocalcinosis
chronic hypokalaemia
and recurrent dehydration

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Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

Gitelman Syndrome

Both are inherited salt-wasting tubulopathies causing hypokalaemic metabolic alkalosis; however, Gitelman affects the distal convoluted tubule and features hypocalciuria, whereas Bartter affects the loop of Henle and typically features hypercalciuria.

Pseudo-Bartter Syndrome

Mimics Bartter syndrome clinically and biochemically but is acquired through surreptitious loop diuretic abuse, chronic vomiting, or laxative abuse rather than a genetic tubular defect.

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Gitelman Syndrome

Key Distinguishing Feature: Typically presents in late childhood or adulthood with hypomagnesaemia and hypocalciuria, whereas Bartter syndrome usually presents earlier with hypercalciuria and normal magnesium.

Surreptitious Diuretic Abuse

Key Distinguishing Feature: Urine diuretic screen is positive for loop diuretics (e.g., furosemide), and urine chloride is high, but genetic testing for Bartter mutations is negative.

Cystic Fibrosis (Pseudo-Bartter presentation)

Key Distinguishing Feature: Infants with CF can present with hypokalaemic, hypochloraemic metabolic alkalosis due to excessive sweat chloride loss, but will have positive sweat chloride testing and respiratory/GI symptoms.

Primary Hyperaldosteronism (Conn's Syndrome)

Key Distinguishing Feature: Presents with hypertension and suppressed renin levels, whereas Bartter syndrome features normotension/hypotension and markedly elevated renin.

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Clinical Pearls

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Urine chloride is the critical first step in evaluating unexplained metabolic alkalosis; a high urine chloride (> 20 mmol/L) in a normotensive patient points to a renal salt-wasting state like Bartter syndrome, whereas a low urine chloride suggests extrarenal losses like vomiting.

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Hypercalciuria is a hallmark of most Bartter syndrome subtypes (especially antenatal forms) and frequently leads to nephrocalcinosis; routine renal ultrasounds are mandatory for monitoring.

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Indometacin and other NSAIDs are mainstays of therapy because they inhibit the excessive renal prostaglandin E2 production that drives renin release and polyuria in Bartter syndrome.

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Type IV Bartter syndrome is uniquely associated with sensorineural deafness due to the role of the barttin protein in both the thick ascending limb and the stria vascularis of the inner ear; always ask about hearing deficits in these patients.

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Example Usage & SOAP

CLINICAL SENTENCE

"A 4-year-old boy with a history of failure to thrive and recurrent dehydration presented with severe hypokalaemic, hypochloraemic metabolic alkalosis, hypercalciuria, and markedly elevated renin and aldosterone levels, consistent with classic Bartter syndrome."

IN A SOAP NOTE

S: Mother reports the 6-month-old infant is constantly thirsty, has frequent wet nappies, and is failing to gain weight along the growth curve. O: Vitals: BP 85/50 mmHg, HR 135 bpm. Weight < 3rd percentile. Mucous membranes dry. Labs: Na 136 mmol/L, K 2.4 mmol/L, Cl 88 mmol/L, HCO3 32 mmol/L, Mg 0.8 mmol/L. Urine Cl 45 mmol/L, Urine Ca/Cr ratio elevated. Renal US shows early medullary echogenicity. A: Hypokalaemic metabolic alkalosis with renal salt wasting and hypercalciuria, highly suspicious for Bartter syndrome (likely Type I or II given early onset and nephrocalcinosis risk). P: Admit for IV fluid and electrolyte correction. Start oral potassium chloride and indometacin. Send tubulopathy genetic panel. Consult Paediatric Nephrology.

DIFFERENTIAL DIAGNOSIS CONTEXT

Differential for hypokalaemic metabolic alkalosis with normal/low blood pressure: (1) Bartter syndrome — look for hypercalciuria, early onset, and elevated urine prostaglandins; (2) Gitelman syndrome — look for hypomagnesaemia and hypocalciuria, usually later onset; (3) Surreptitious loop diuretic abuse — check urine toxicology for diuretics; (4) Cystic fibrosis — check sweat chloride, as excessive sweat electrolyte loss can mimic Bartter biochemically; (5) Severe vomiting (e.g., pyloric stenosis) — urine chloride will be low (< 20 mmol/L).

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Prognosis

SHORT-TERM OUTCOME

With aggressive electrolyte replacement and NSAID therapy, acute salt-wasting crises and severe dehydration can be stabilised within days to weeks, though polyuria and hypokalaemia require continuous daily management.

LONG-TERM PROGNOSIS

Long-term prognosis depends on the subtype and adherence to therapy; many patients with classic Type III Bartter syndrome achieve normal adult height and renal function, whereas severe antenatal forms carry a higher risk of chronic kidney disease, persistent growth restriction, and complications from nephrocalcinosis.

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References & Coding

ICD-10 DIAGNOSTIC CODE

E26.8

LITERATURE CITATIONS & GUIDELINES

[1]Konrad M et al. Diagnosis and management of Bartter syndrome: executive summary of a consensus and guidance from an international expert panel. Kidney Int. 2021;99(2):308-316.

[2]Blanchard A et al. Gitelman syndrome: consensus and guidance from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference. Kidney Int. 2017;91(6):1293-1305.

[3]Seyberth HW, Schlingmann KP. Bartter- and Gitelman-tubular disorders. Best Pract Res Clin Endocrinol Metab. 2011;25(5):739-750.

[4]Bokhari SRA et al. Bartter Syndrome. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023.

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.