The diagnosis is suggested by the finding of hypokalemia; the serum potassium
Level is usually less than 2.5 meq/L. Supportive findings include normal blood
Pressure; defective platelet aggregation; hypochloremia; metabolic alkalosis;
Elevated plasma levels of renin, aldosterone, and prostaglandin E2 ; and high
Urinary levels of potassium and chloride. Some patients may also have
Hypercalciuria, hyperuricemia, hypomagnesemia, and urinary sodium wasting. The
Diagnosis may be confirmed by the histologic demonstration of hyperplasia of the
Juxtaglomerular apparatus, but this abnormality is not found in all patients and
Is frequently absent in young children.
Bartter syndrome must be differentiated from licorice abuse, laxative or
Diuretic use, persistent vomiting or diarrhea, pyelonephritis, and diabetes
Insipidus. Several of these (laxative use, vomiting, diarrhea, diabetes
Insipidus) are associated with hypovolemia, which results in a low urinary
Chloride level, whereas Bartter syndrome is associated with an elevated level.
Bartter syndrome may be confused with Gitelman syndrome. Both disorders are
Associated with hypokalemia, renal potassium wasting, activation of the
Renin-angiotensin-aldosterone axis, and normal blood pressure. Gitelman syndrome
Commonly presents in older children and young adults with muscle weakness,
Carpopedal spasms, or tetany. Patients with Bartter syndrome have normal to
Decreased serum magnesium levels, normal urinary magnesium excretion, and normal
To increased calcium excretion; patients with Gitelman syndrome have
Hypomagnesemia, increased urinary magnesium, and decreased calcium excretion.
Gitelman syndrome results from a mutation of the gene for the thiazide-sensitive
Sodium-chloride co-transporter of the distal tubule located on chromosome 16.