Hyponatremic-hypertensive syndrome with extensive and reversible renal defects.

Two young children with renal artery stenosis and severe hypertension who presented with the so-called hyponatremic-hypertensive syndrome (HHS), with marked urine and solute loss during the acute phase, are described. Both children also presented with severe high molecular proteinuria, glycosuria, and hypercalciuria, only the first symptom having prompt remission after normalization of blood pressure. In children with renal artery stenosis, HHS is associated with severe proteinuria due to hyperfiltration and more extensive tubular functional alterations. Hyponatremia and acute tubulopathy may mask the presenting clinical picture of renal artery stenosis.