Bartter syndrome

Lore & Background

Bartter syndrome is caused by mutations of genes encoding proteins that transport ions across renal cells in the thick ascending limb of the nephron. Specifically, mutations directly or indirectly involving the Na-K-2Cl cotransporter are key. Loss of function of this reabsorption system results in decreased sodium, potassium, and chloride reabsorption, as well as abolishment of the lumen-positive voltage, leading to decreased calcium and magnesium reabsorption. This also impairs water reabsorption, causing significant diuresis and potential volume depletion.

Reader's Guide

Bartter syndrome is significant as a model for understanding renal ion transport and the effects of loop diuretics, given that the syndrome mimics the action of drugs like furosemide. The condition highlights the critical role of the thick ascending limb in electrolyte and water balance. Early diagnosis and treatment can improve growth and intellectual development in children, while sustained hypokalemia and hyperreninemia can lead to progressive kidney disease. The syndrome also underscores the genetic heterogeneity of inherited tubulopathies, with multiple subtypes based on different gene mutations.

Did You Know?

• Neonatal Bartter syndrome is seen in 90% of cases between 24 and 30 weeks of gestation with excess amniotic fluid.
• About 85% of infants with neonatal Bartter syndrome dispose of excess calcium in the urine and may develop kidney stones.
• Bartter syndrome symptoms are identical to those of patients on loop diuretics like furosemide.
• Pseudo-Bartter's syndrome has been seen in cystic fibrosis and excessive use of laxatives.