Liddle syndrome in a newborn infant

A 10-week-old female infant developed hypertension. The elevated blood pressure was associated with metabolic alkalosis and urinary chloride wastage. The family history was unremarkable. Her urinalysis, blood urea nitrogen (BUN), and serum creatinine concentrations were all normal. A renal ultrasound was normal. A technetium-99m diethylenetriaminopentoacetic acid (DTPA) renal scan with captopril showed normal blood flow bilaterally. The head ultrasound and echocardiogram were normal. Blood epinephrine, norepinephrine, catecholamines, thyroxine, and steroid levels were also normal. Treatment with various combinations of labetalol, hydralazine, captopril, methyldopa, nifedipine, and spironolactone, all at high doses, failed to control the elevated blood pressure. Serum aldosterone level and peripheral plasma renin activity were low. The lack of therapeutic response to spironolactone, with a good response to amiloride and recurrence of hypertension and metabolic alkalosis after amiloride cessation that was subsequently treated with amiloride, established the diagnosis of Liddle syndrome. To our knowledge, this is the youngest patient with Liddle syndrome that has been reported in the literature.