Bartter syndrome type 1

Bartter syndrome type 1 (also known as antenatal Bartter syndrome type 1 or neonatal Bartter syndrome type 1) is a rare inherited kidney disorder caused by mutations in the SLC12A1 gene, which encodes the sodium-potassium-chloride cotransporter (NKCC2) located in the thick ascending limb of the loop of Henle. This transporter plays a critical role in reabsorbing sodium, potassium, and chloride from the urine back into the body. When it is dysfunctional, excessive amounts of these electrolytes are lost in the urine, leading to severe salt wasting, hypokalemia (low potassium), hypochloremic metabolic alkalosis, and elevated levels of renin and aldosterone (hyperreninemic hyperaldosteronism) without high blood pressure. Bartter syndrome type 1 is one of the most severe forms of Bartter syndrome and typically presents before birth or in the neonatal period. During pregnancy, affected fetuses produce excessive urine, leading to polyhydramnios (excess amniotic fluid), which can cause premature birth. After birth, affected infants exhibit polyuria (excessive urination), polydipsia (excessive thirst), failure to thrive, dehydration, and electrolyte imbalances. Hypercalciuria (excessive calcium in the urine) is a prominent feature and can lead to nephrocalcinosis (calcium deposits in the kidneys), which may progressively impair kidney function over time. Some patients may also develop fever episodes related to dehydration. Treatment for Bartter syndrome type 1 is supportive and aimed at correcting electrolyte imbalances and preventing complications. This includes aggressive fluid and electrolyte replacement, particularly potassium and sodium chloride supplementation. Nonsteroidal anti-inflammatory drugs (NSAIDs), most commonly indomethacin, are frequently used to reduce renal prostaglandin production, which helps decrease urinary salt and water losses. Potassium-sparing diuretics such as spironolactone or amiloride may also be used. With early diagnosis and consistent management, many patients can achieve improved growth and quality of life, though lifelong treatment and monitoring of kidney function are required.

Common questions about Bartter syndrome type 1