What are the diagnostic criteria for Bartter syndrome?

From the Guidelines

Diagnosing Bartter syndrome requires a comprehensive approach combining clinical evaluation, laboratory tests, and genetic analysis, with a focus on identifying characteristic symptoms and confirming the diagnosis through genetic testing whenever possible 1. To diagnose Bartter syndrome, the following steps should be taken:

• Evaluate the medical history, including polyhydramnios, premature birth, growth failure, and family history 1
• Conduct biochemical parameter tests, including serum electrolytes, acid-base status, renin, aldosterone, creatinine, fractional excretion of chloride, and urinary calcium-creatinine ratio 1
• Perform a renal ultrasound to detect medullary nephrocalcinosis and/or kidney stones 1
• Confirm the clinical diagnosis of BS by means of genetic analysis whenever possible, as recommended by the European Rare Kidney Disease Reference Network Working Group for Tubular Disorders 1 Key laboratory tests include:
• Serum electrolytes to show hypokalemia, metabolic alkalosis, and normal or low blood pressure
• Urinary electrolytes to reveal increased potassium, sodium, and chloride excretion
• Plasma renin and aldosterone levels, which are typically elevated It is essential to exclude conditions with similar presentations, such as diuretic abuse, laxative abuse, vomiting, and Gitelman syndrome, and to consider genetic counseling for families with probands with confirmed clinical and/or genetic diagnosis of BS 1. Genetic testing is crucial in confirming the diagnosis and determining the specific type of Bartter syndrome, and it is recommended to prioritize genetic analysis over tubular function tests with furosemide or thiazides whenever possible 1.

From the Research

Diagnosis of Bartter Syndrome

To diagnose Bartter syndrome, the following steps can be taken:

• Identify the clinical presentation, which typically includes salt wasting, hypokalemia, and metabolic alkalosis 2
• Perform genetic testing to identify mutations in the genes encoding the transporters and channels involved in salt reabsorption in the thick ascending limb of the loop of Henle 2
• Conduct phenotypic identification, which remains the first step to guide the suspicion of Bartter syndrome 2
• Consider the interaction with other cotransporters and different degrees of compensation through alternative pathways, which can affect the phenotype-genotype relationship 2

Challenges in Diagnosis

• The rarity of the syndrome and the lack of genetic characterization in most cases can make diagnosis challenging 2
• Limited clinical evidence for treatment is available, and therapy is often based on the physician's personal experience and comprehension of renal physiology 2