Bartter Syndrome: A Systematic Review of Case Reports and Case Series.

Background and Objectives: Bartter syndrome (BS) is a rare group of autosomal-recessive disorders that usually presents with hypokalemic metabolic alkalosis, occasionally with hyponatremia and hypochloremia. The clinical presentation of BS is heterogeneous, with a wide variety of genetic variants. The aim of this systematic review was to examine the available literature and provide an overview of the case reports and case series on BS. Materials and Methods: Case reports/series published from April 2012 to April 2022 were searched through Pubmed, JSTOR, Cochrane, ScienceDirect, and DOAJ. Subsequently, the information was extracted in order to characterize the clinical presentation, laboratory results, treatment options, and follow-up of the patients with BS. Results: Overall, 118 patients, 48 case reports, and 9 case series (n = 70) were identified. Out of these, the majority of patients were male (n = 68). A total of 21 patients were born from consanguineous marriages. Most cases were reported from Asia (73.72%) and Europe (15.25%). In total, 100 BS patients displayed the genetic variants, with most of these being reported as Type III (n = 59), followed by Type II (n = 19), Type I (n = 14), Type IV (n = 7), and only 1 as Type V. The most common symptoms included polyuria, polydipsia, vomiting, and dehydration. Some of the commonly used treatments were indomethacin, potassium chloride supplements, and spironolactone. The length of the follow-up time varied from 1 month to 14 years. Conclusions: Our systematic review was able to summarize the clinical characteristics, presentation, and treatment plans of BS patients. The findings from this review can be effectively applied in the diagnosis and patient management of individuals with BS, rendering it a valuable resource for nephrologists in their routine clinical practice.

Genetic diagnosis and treatment of hereditary renal tubular disease with hypokalemia and alkalosis.

Renal tubules play an important role in maintaining water, electrolyte, and acid-base balance. Renal tubule dysfunction can cause electrolyte disorders and acid-base imbalance. Clinically, hypokalemic renal tubular disease is the most common tubule disorder. With the development of molecular genetics and gene sequencing technology, hereditary renal tubular diseases have attracted attention, and an increasing number of pathogenic genes related to renal tubular diseases have been discovered and reported. Inherited renal tubular diseases mainly occur due to mutations in genes encoding various specific transporters or ion channels expressed on the tubular epithelial membrane, leading to dysfunctional renal tubular reabsorption, secretion, and excretion. An in-depth understanding of the molecular genetic basis of hereditary renal tubular disease will help to understand the physiological function of renal tubules, the mechanism by which the kidney maintains water, electrolyte, and acid-base balance, and the relationship between the kidney and other systems in the body. Meanwhile, understanding these diseases also improves our understanding of the pathogenesis of hypokalemia, alkalosis and other related diseases and ultimately promotes accurate diagnostics and effective disease treatment. The present review summarizes the most common hereditary renal tubular diseases (Bartter syndrome, Gitelman syndrome, EAST syndrome and Liddle syndrome) characterized by hypokalemia and alkalosis. Further detailed explanations are provided for pathogenic genes and functional proteins, clinical manifestations, intrinsic relationship between genotype and clinical phenotype, diagnostic clues, differential diagnosis, and treatment strategies for these diseases.

Bartter and Gitelman syndromes.

Bartter and Gitelman syndromes belong to salt-losing tubulopathies. These rare diseases may be associated with severe electrolyte disorders. Early identification of tubulopathies is essential for appropriate management. Progress in molecular genetics enabled the identification of genes and pathophysiologic mechanisms associated with these diseases. Here, we review etiology and diagnostics of these disorders from the light of current knowledge. Additionally, we discuss contemporary therapeutic approaches.

Clinical Course of Patients with Bartter Syndrome.

INTRODUCTION: Bartter syndrome (BS) is a salt losing tubulopathy due to impairment of the transport mechanisms at the thick ascending limb of the Henle's loop. The aim of this study was to report the clinical course of patients with BS. METHODS: Patients with BS were followed from 1996 to 2020 and enrolled to a systematic protocol to confirm primary BS by evaluating the metabolic derangements, nephrolithiasis and nephrocalcinosis. Treatment was based on standard guidelines. Comparisons were made between data at baseline and at the last visit. RESULTS: A total of 13 patients (7 males) with primary BS were analyzed. Two patients had a mutation of the KCNJ1 gene. Age at diagnosis was 3 ± 4.5 years and the follow-up period was 11.19 ± 6.76 years. Metabolic alkalosis was initially detected in 76.92% and remained stable at the last visit (P > .05). Hypokalemia was present in 61.5% of patients at diagnosis, but sustained in 38.46% at the last visit (P < .05). Urine calcium level was 13.3 ± 9.6 mg/ kg/d at the first visit, and significantly reduced to 3.7 ± 2.0 mg/ kg/d at the last visit (P < .05). Nephrocalcinosis was detected by first kidney ultrasonography in 53.8% of patients. Kidney function was preserved, with a glomerular filtration rate of 120.1 ± 28.7 mL/min/ 1.73m2 at last visit. Growth was completely recovered in 71.42% and partially improved in 14.28% of patients after treatment, respectively. All patients received indomethacin and potassium chloride salts. CONCLUSIONS: Long-term follow-up of this cohort of BS showed favorable outcomes after treatment resulting in metabolic normalization and growth catch-up in most patients.  DOI: 10.52547/ijkd.6657.

Molecular Basis, Diagnostic Challenges and Therapeutic Approaches of Bartter and Gitelman Syndromes: A Primer for Clinicians.

Gitelman and Bartter syndromes are rare inherited diseases that belong to the category of renal tubulopathies. The genes associated with these pathologies encode electrolyte transport proteins located in the nephron, particularly in the Distal Convoluted Tubule and Ascending Loop of Henle. Therefore, both syndromes are characterized by alterations in the secretion and reabsorption processes that occur in these regions. Patients suffer from deficiencies in the concentration of electrolytes in the blood and urine, which leads to different systemic consequences related to these salt-wasting processes. The main clinical features of both syndromes are hypokalemia, hypochloremia, metabolic alkalosis, hyperreninemia and hyperaldosteronism. Despite having a different molecular etiology, Gitelman and Bartter syndromes share a relevant number of clinical symptoms, and they have similar therapeutic approaches. The main basis of their treatment consists of electrolytes supplements accompanied by dietary changes. Specifically for Bartter syndrome, the use of non-steroidal anti-inflammatory drugs is also strongly supported. This review aims to address the latest diagnostic challenges and therapeutic approaches, as well as relevant recent research on the biology of the proteins involved in disease. Finally, we highlight several objectives to continue advancing in the characterization of both etiologies.

Diagnosis and management of Bartter syndrome: executive summary of the consensus and recommendations from the European Rare Kidney Disease Reference Network Working Group for Tubular Disorders.

Bartter syndrome is a rare inherited salt-losing renal tubular disorder characterized by secondary hyperaldosteronism with hypokalemic and hypochloremic metabolic alkalosis and low to normal blood pressure. The primary pathogenic mechanism is defective salt reabsorption predominantly in the thick ascending limb of the loop of Henle. There is significant variability in the clinical expression of the disease, which is genetically heterogenous with 5 different genes described to date. Despite considerable phenotypic overlap, correlations of specific clinical characteristics with the underlying molecular defects have been demonstrated, generating gene-specific phenotypes. As with many other rare disease conditions, there is a paucity of clinical studies that could guide diagnosis and therapeutic interventions. In this expert consensus document, the authors have summarized the currently available knowledge and propose clinical indicators to assess and improve quality of care.

Bartter's syndrome: clinical findings, genetic causes and therapeutic approach.

BACKGOUND: Bartter's syndrome (BS) is a rare group of salt losing tubulopathies due to the impairment of transport mechanisms at the thick ascending limb of the Henle's loop. DATA SOURCES: Literature reviews and original research articles were collected from database, including PubMed and Scopus. RESULTS: According to the time of onset and symptoms, BS can be classified into antenatal and classic BS. Molecular studies have identified different subtypes of BS. BS types I, II and III are caused by mutations on genes encoding the luminal Na+-K+-2Cl- co-transporter, the luminal K+ channel ROMK, and the basolateral chloride channel ClC-Kb (CLCNKB), respectively. Loss-of-function mutations of Barttin CLCNK type accessory beta subunit cause BS type IVa. Simultaneous mutations of CLCNKB and CLCNKA cause BS type IVb. BS type V consists in a novel transient form characterized by antenatal presentation due to mutations in the MAGE family member D2. Severe gain-of-function mutations of the extracellular calcium sensing receptor gene can result in an autosomal dominant condition of BS. Main clinical and biochemical alterations in BS include polyuria, dehydration, hypokalemia, hypochloremic metabolic alkalosis, hyperreninemia, high levels of prostaglandins, normal or low blood pressure, hypercalciuria and failure to thrive. Treatment focuses mainly at correcting dehydration and electrolyte disturbances and in measures to reduce polyuria, including the use of nonsteroidal anti-inflammatory medications to control excessive renal prostaglandin E2 production. CONCLUSIONS: Early diagnosis and treatment of BS may prevent long-term consequences such as growth failure, nephrocalcinosis and end-stage renal disease.

[Bartter-Gitelman syndromes]. / Syndromes de Bartter­Gitelman.

Bartter-Gitelman syndromes are rare inherited autosomal recessive salt-losing tubulopathies characterized by severe and chronic hypokalemia associated with metabolic alkalosis and secondary hyperaldosteronism. Bartter syndrome results from a furosemide-like defect in sodium reabsorption in the Henle's loop leading to hypercalciuria and defect in urinary concentration capacity. The antenatal Bartter syndrome is defined by polyhydramnios and an infantile polyuria with severe dehydration whereas classic Bartter syndrome appears during childhood or adulthood. Gitelman syndrome is a thiazide-like salt-losing tubulopathy. It is associated with hypomagnesemia, hypocalciuria without defect in urinary concentration capacity. The diagnosis is most often made in adolescents or adults. Clinical symptoms include tetany, delay in the height-weight growth curves, chronic tiredness, muscle weakness, myalgia and vertigo. Nephrocalcinosis in Bartter syndrome could lead to chronic kidney disease. Antenatal Bartter syndrome requires hospitalization in intensive care unit to manage the severe newborn dehydration. Chondrocalcinosis is the major complication in the Gitelman syndrome. The corner stones of treatment is the fluid and electrolyte management Bartter and Gitelman syndromes need lifelong oral supplementations of potassium, salt (Bartter) and magnesium (Gitelman). Indomethacin is efficient to reduce water and electrolyte loss in Bartter. In Gitelman, potassium-sparing diuretics may be helping for severe hypokaliemia but they will reinforce hypovolemia.

Inherited salt-losing tubulopathy: An old condition but a new category of tubulopathy.

Bartter syndrome (BS) and Gitelman syndrome (GS) are syndromes associated with congenital tubular dysfunction, characterized by hypokalemia and metabolic alkalosis. Clinically, BS is classified into two types: the severe antenatal/neonatal type, which develops during the fetal period with polyhydramnios and preterm delivery; and the relatively mild classic type, which is usually found during infancy with failure to thrive. GS can be clinically differentiated from BS by its age at onset, usually after school age, or laboratory findings of hypomagnesemia and hypocalciuria. Recent advances in molecular biology have shown that these diseases can be genetically classified into type 1 to 5 BS and GS. As a result, it has become clear that the clinical classification of antenatal/neonatal BS, classic BS, and GS does not always correspond to the clinical symptoms associated with the genotypes in a one-to-one manner; and there is clinically no clear differential border between type 3 BS and GS. This has caused confusion among clinicians in the diagnosis of these diseases. It has been proposed that the disease name "inherited salt-losing tubulopathy" can be used for cases of tubulopathies accompanied by hypokalemia and metabolic alkalosis. It is reasonable to use this term prior to genetic typing into type 1-5 BS or GS, to avoid confusion in a clinical setting. In this article, we review causative genes and phenotypic correlations, diagnosis, and treatment strategies for salt-losing tubulopathy as well as the clinical characteristics of pseudo-BS/GS, which can also be called a "salt-losing disorder".

Bartter syndrome: An infrequent tubulopathy of prenatal onset. / Síndrome de Bartter: Una tubulopatía infrecuente de inicio antenatal.

INTRODUCTION: Bartter syndrome (BS) is a rare inherited tubulopathy that has two presentation forms, the first one is a severe form of antenatal onset (neonatal Bartter) and the second one is a later on set form during the first years of life (classic Bartter). In the antenatal form, it manifests with fetal polyuria, polyhydramnios of early and severe onset, premature delivery, and intrauterine growth restriction. In the postnatal stage, it presents recurrent episodes of dehydration and electrolyte im balance that can compromise the survival of the patient. OBJECTIVE: To report a clinical case of neo natal BS and a review of the literature. CLINICAL CASE: Premature newborn of 35 weeks of gestation with history of severe polyhydramnios diagnosed at 27 weeks of gestation, without apparent cause. From birth, the patient presented polyuria and hypokalemic metabolic alkalosis making a diagnosis of Neonatal Bartter Syndrome in the first week of life. Laboratory tests confirmed urinary electrolyte losses. The patient was treated with strict water balance and sodium and potassium supplementa tion, achieving weight and electrolyte imbalance stabilization. The patient remains in control in the nephrology unit, with potassium gluconate and sodium chloride supplementation. At the fourth month, ibuprofen was added as part of treatment. At the seventh month of life, renal ultrasound showed nephrocalcinosis. At one year of life, profound sensorineural hearing loss was observed re quiring a cochlear implant. CONCLUSION: The presence of severe polyhydramnios of early onset with no identified cause should lead to suspicion of neonatal BS which even when infrequent determines severe hydroelectrolytic alterations and should be treated early.

Síndrome de Bartter: una tubulopatía infrecuente de inicio antenatal / Bartter syndrome: an infrequent tubulopathy of prenatal onset

INTRODUCCIÓN: Síndrome de Bartter (SB) es una tubulopatía hereditaria, poco frecuente que tiene dos formas de presentación, forma grave de inicio antenatal (Bartter neonatal) y forma de aparición más tardía (Bartter clásico). En su forma antenatal se manifiesta con poliuria fetal, polihidroamnios de inicio precoz y severo, parto prematuro secundario y restricción de crecimiento intrauterino. La etapa postnatal presenta episodios recurrentes de deshidratación y desbalance electrolítico que pue den comprometer la sobrevida del paciente. OBJETIVO: Comunicar un caso de SB neonatal y presentar una revisión de la literatura en esta patología. CASO CLÍNICO: Prematuro 35 semanas, con antecedente de severo polihidroamnios diagnosticado a las 27 semanas de gestación, sin causa aparente. Desde su nacimiento evolucionó con poliuria y alcalosis metabólica hipokalémica haciendo plantear, en primera semana de vida, diagnóstico de Síndrome de Bartter neonatal. El laboratorio confirmó per didas urinarias de electrólitos. Fue manejado con balance hídrico estricto y suplementación de sodio y potasio, logrando estabilizar peso y desbalance electrolítico. Se mantiene en control nefrológico, con suplementación de gluconato de potasio y cloruro de sodio. Se agregó ibuprofeno al cuarto mes como parte del tratamiento. Al séptimo mes de vida, ecografía renal demostró nefrocalcinosis. Al año de vida se evidenció hipoacusia sensorioneural profunda requiriendo implante coclear. CONCLUSIÓN: Presencia de polihidroamnios severo de aparición temprana sin causa identificada debe hacer sospechar SB, que aun siendo infrecuente determina graves alteraciones hidroelectrolíticas y debe ser iniciado su tratamiento precozmente.

INTRODUCTION: Bartter syndrome (BS) is a rare inherited tubulopathy that has two presentation forms, the first one is a severe form of antenatal onset (neonatal Bartter) and the second one is a later on set form during the first years of life (classic Bartter). In the antenatal form, it manifests with fetal polyuria, polyhydramnios of early and severe onset, premature delivery, and intrauterine growth restriction. In the postnatal stage, it presents recurrent episodes of dehydration and electrolyte im balance that can compromise the survival of the patient. OBJECTIVE: To report a clinical case of neo natal BS and a review of the literature. CLINICAL CASE: Premature newborn of 35 weeks of gestation with history of severe polyhydramnios diagnosed at 27 weeks of gestation, without apparent cause. From birth, the patient presented polyuria and hypokalemic metabolic alkalosis making a diagnosis of Neonatal Bartter Syndrome in the first week of life. Laboratory tests confirmed urinary electrolyte losses. The patient was treated with strict water balance and sodium and potassium supplementa tion, achieving weight and electrolyte imbalance stabilization. The patient remains in control in the nephrology unit, with potassium gluconate and sodium chloride supplementation. At the fourth month, ibuprofen was added as part of treatment. At the seventh month of life, renal ultrasound showed nephrocalcinosis. At one year of life, profound sensorineural hearing loss was observed re quiring a cochlear implant. CONCLUSION: The presence of severe polyhydramnios of early onset with no identified cause should lead to suspicion of neonatal BS which even when infrequent determines severe hydroelectrolytic alterations and should be treated early.

Bartter Syndrome and Gitelman Syndrome.

Bartter and Gitelman syndromes are conditions characterized by renal salt-wasting. Clinical presentations range from severe antenatal disease to asymptomatic with incidental diagnosis. Hypokalemic hypochloremic metabolic alkalosis is the common feature. Bartter variants may be associated with polyuria and weakness. Gitelman syndrome is often subtle, and typically diagnosed later life with incidental hypokalemia and hypomagnesemia. Treatment may involve fluid and electrolyte replenishment, prostaglandin inhibition, and renin-angiotensin-aldosterone system axis disruption. Investigators have identified causative mutations but genotypic-phenotypic correlations are still being characterized. Collaborative registries will allow improved classification schema and development of effective treatments.

Bartter syndrome-like phenotype in a patient with diabetes: a case report.

BACKGROUND: Bartter's syndrome is a rare genetic tubulopathy affecting the loop of Henle leading to salt wasting. It is commonly seen in utero or in early neonatal period. Rare cases of acquired Bartter's syndrome are reported in association with infections like tuberculosis, granulomatous conditions like sarcoidosis, autoimmune diseases, and drugs. The mainstay of management includes potassium, calcium, and magnesium supplementation. CASE PRESENTATION: We report the case of a 62-year-old Sri Lankan Sinhalese man with diabetes and hypertension presenting with generalized weakness with clinical evidence of proximal myopathy. He was severely hypokalemic with high urinary potassium excretion and hypochloremic metabolic alkalosis. He poorly responded to intravenously administered potassium supplements. A diagnosis of idiopathic Bartter-like phenotype was made. He responded well to spironolactone and indomethacin. CONCLUSIONS: Patients presenting with body weakness need serum potassium estimation. Acquired Bartter's syndrome although rare, should be ruled out in those with hypokalemia and metabolic alkalosis with increased urinary potassium loss with poor response to potassium replacement.

Neonatal bartter syndrome in an extremely low birth weight baby.

Early diagnosis of Bartter syndrome (BS) in the neonatal period is a clinical challenge, more so in an extremely low birth weight (ELBW) baby because of the inherent renal immaturity and the associated difficulty in fluid management. However, once a diagnosis is made, the disorder is known to respond well to fluid and electrolyte management, prostaglandin inhibitors, and potassium-sparing diuretics. Herein, we report a case of neonatal BS in a very premature ELBW infant.

[Poor weight gain, recurrent metabolic alkalosis and hypokalemia in a neonate].

The study reports a female neonate with a gestational age of 29+2 weeks and a birth weight of 1 210 g. Ten minutes after birth, the neonate was admitted to the hospital due to shortness of breath. Several days after birth, the neonate presented with hyperglycemia, polyuria, and poor weight gain, accompanied by azotemia, hypochloremic metabolic alkalosis, hypokalemia, and hyponatremia. Laboratory examinations showed elevated levels of aldosterone, renin, and angiotensin II. Gene detection revealed SLC12A1 gene mutation. Neonatal Bartter syndrome was thus confirmed. The neonate was treated with sodium and potassium supplements, and was followed up for 8 months. During the follow-up, the mental and neural development of the neonate was almost normal at the corrected age, and regular reexaminations showed slight metabolic alkalosis and almost normal electrolyte levels. For the neonates who have the symptoms of unexplainable polyurine and electrolyte disorders, it is important to examine the levels of aldosterone, renin and angiotensin. A definite diagnosis of neonatal Bartter syndrome can be made based on the presence of SLC12A1 gene mutation.

Bartter's and Gitelman's syndrome.

PURPOSE OF REVIEW: The clinical presentations of Bartter's syndrome and Gitelman's syndrome will be reviewed including two most recently described hypokalemic salt-losing tubulopathies. By taking the quite heterogeneous presentations and the apparently different pathophysiologies as the basis, the applicability of the physiologic classification has been tested. RECENT FINDINGS: According to the physiologic approach, salt-losing tubulopathies can be divided into two major groups (with completely different tubular defects): first, disorders of the thick ascending limb of Henle's loop (loop disorders); second, disorders of the distal convolute tubule (DCT disorders). A combination of these two groups with complety different tubular defects will finally lead to a third group: the combined loop/DCT disorders. On the basis of pharmacologic tests (pharmacotyping), it appears that the Bartter's syndrome V belongs to the DCT group, whereas the most recently described transient antenatal Bartter's syndrome best fits in the group with the loop and DCT combination.Besides secondary hyperaldosteronism, loop disorders present a whole spectrum of (secondary) pathophysiologic characteristics with significant diagnostic and therapeutic impact, such as polyhydramnios, hyperprostaglandinuria, nephrogenic diabetes insipidus, and nephrocalcinosis. Recent reports indicate that neonatal hyperparathyroidism has also to be added to the clinical presentation of isolated loop disorders. SUMMARY: As long as gene therapy is not available, the overall therapeutic management follows the clinical presentation, which leads to the underlying pathophysiology of renal salt wasting. Thus, when dealing with Bartter's syndrome and Gitelman's syndrome, the correct physiologic and pharmacologic characterization appears to be essential for a sound diagnostic and therapeutic patient management.