Bartter's Syndrome - the Case for a Primary Potassium-Losing Tubulopathy: Discussion Paper

Exogenous prostaglandin administration and pseudo-Bartter syndrome

Biological abnormalities simulating Bartter syndrome were observed in a preterm neonate with complex cyanotic congenital heart disease, for which ductus arteriosus was maintained open by high doses of prostaglandin (PG) until a Blalock shunt could be performed. These abnormalities spontaneously disappeared after cessation of PG administration. We postulate that the natriuretic effect of exogenous administered PG could further increase sodium wasting already induced by the cardiopathy thus leading to pseudo-Bartter syndrome.

Hypokalemia with nephrocalcinosis: a variant of Bartter's syndrome

A 28-year-old male presented with profound hypokalemia and was found to have a variant of Bartter's syndrome with nephrocalcinosis, hypercalciuria, normal distal fractional reabsorption of chloride and normal sodium delivery to the distal tubule.

Correction of hypokalemia in Bartter's syndrome by enalapril

Seven patients with Bartter's syndrome were investigated before and after 3 months' treatment by enalapril. Serum potassium rose from 2.4 +/- 0.5 to 3.9 +/- 0.6 mmol/L. In all patients, serum magnesium rose and bicarbonate fell. Hormonal changes were as suspected: a further stimulation of renin and a decline in aldosterone. The BP sensitivity to angiotensin II normalized in the five patients in whom the test was performed. Clearance studies during maximal water diuresis, performed in four patients, were compatible with a high proximal fractional tubular sodium reabsorption and a relatively low distal fractional sodium reabsorption. Fractional free water excretion after furosemide was also low, confirming the concept of a primary sodium reabsorption defect in the furosemide-insensitive part of the nephron in Bartter's syndrome. The only consistent change after enalapril was a further decline in distal fractional sodium reabsorption. Initiation of therapy produced a BP fall in each subject. Clinical important hypotension associated with oliguria was seen twice, but these reactions were short-lasting. The BP rose to pretreatment values within 72 hours, despite continuation of converting-enzyme inhibition. Renal function recovered, though a moderate fall in function persisted. No other side effects were noticed. We conclude that converting-enzyme inhibition improves the potassium metabolism of patients with Bartter's syndrome, without ameliorating the abnormal renal sodium handling.

Hypokalaemia: Bartter's Syndrome or Pseudo-Bartter's Syndrome?

The difficulties in the diagnosis of hypokalaemia are often considerable. This paper reports three patients who presented with hypokalaemia. Investigations are described which may help to distinguish Bartter's syndrome from pseudo-Bartter's syndrome.