Bartter's syndrome is a rare disease that most often presents in the neonatal period or early childhood with polyuria, polydipsia, salt craving, and growth retardation. Blood pressure is normal or low. Metabolic abnormalities include hypokalemia, hypochloremic metabolic alkalosis, decreased urinary concentrating and diluting ability, hypercalciuria with nephrocalcinosis, mild hypomagnesemia, and increased urinary prostaglandin excretion. 

Bartter's syndrome is a condition in which there appears to be a primary defect in the loop of Henle salt absorption. This leads to chronic increases in distal delivery and a chronic state of mild volume contraction. Patients are hypokalemic, with very high renin and aldosterone levels.

The diagnosis is usually made based on clinical presentation and laboratory findings. The diagnosis in the neonatal infant is suggested by severe hypokalemia, usually <2.5 mmol/L, with metabolic alkalosis. Hypercalciuria is typical; hypomagnesemia is seen in a minority of patients but is more common in Gitelman syndrome. Because features of Bartter syndrome resemble chronic loop diuretic use, diuretic abuse should be considered in the differential diagnosis, even in young children. Chronic vomiting may also give a similar clinical picture but can be distinguished by measurement of urinary chloride, which is elevated in Bartter syndrome and low in patients with chronic vomiting. Histologically, kidneys demonstrate hyperplasia of the juxtaglomerular apparatus. Renal biopsy samples are rarely performed to diagnose this condition.

Gitelman syndrome (often called a Bartter syndrome variant) is also a rare autosomal recessive cause of hypokalemic metabolic alkalosis, with distinct features of hypocalciuria and hypomagnesemia. Patients with Gitelman syndrome typically present later in childhood or early adulthood.

References:

1. Bartter FC, Pronove P, Gill JR, MacCardle RC. Hyperplasia of the juxtaglomerular complex with hyperaldosteronism and hypokalemic alkalosis. A new syndrome. Am J Med1962; 33:811–28. [Medline]
2. Amirlak I, Dawson KP. Bartter syndrome: an overview. QJM. 2000 Apr;93(4):207-15. [Medline]

Created: Nov 13, 2009