Hyponatraemic-hypertensive syndrome in a 15-month-old child with renal artery stenosis.

In this report we present the case of a 15-month-old girl with hyponatraemic-hypertensive syndrome (HHS) caused by stenosis of the left renal artery. On sonographic examination the contralateral non-stenotic kidney appeared enlarged and with cortical hyperechogenicity mimicking a parenchymal lesion. After successful percutaneous transluminal angioplasty, when the girl became normotensive, her serum electrolyte and acid-base balance became normal within a few days. The contralateral non-stenotic kidney hyperechogenicity also disappeared, but only after a period of 6 months, suggesting parenchymal damage due to tubulointerstitial injury, even though reversible. Our case confirms that renovascular hypertension may rarely also be present with HHS in children and that metabolic and morphological alterations are reversible after the resolution of arterial stenosis.