Abnormal renal excretion, leading to low potassium.

Presents in early childhood with failure to thrive. Could also be constipation, muscle cramps and weakness (potassium needed for membrane potential, so these are all neuromuscular) and non-specific dizziness and fatigue.

Characteristic hypokalemic, hypochloremic metabolic alkalosis. High plasma renin activity and high aldosterone concentration seen.

Gitelman syndrome is similar, less severe (distal tubule, rather than ascending limb of loop of Henle) – less failure to thrive, in fact often asymptomatic detected incidentally. Might present with nocturia/polyuria.

Urinary calcium excretion distinguishes the two syndromes. Bartter’s waste calcium (more severe, after all), Gitelman retain.

Treatment is with supplementation.

Decompensation can be precipitated by diarrhoea or vomiting. Acute treatment can include potassium-sparing diuretics (spironolactone), cyclo-oxygenase inhibitors and renin-angiotensin blockers.

Pseudo-Bartter’s is due to CF.