Liddle syndrome is a rare autosomal dominant disorder of renal epithelial transport that clinically resembles primary aldosteronism, with hypertension and hypokalemic metabolic alkalosis and with low plasma renin and aldosterone levels. The syndrome results from an inherently increased activity of the epithelial sodium channels (ENaC), located on the luminal membrane in the collecting tubule, which accelerates sodium resorption and potassium secretion (underactivity of ENaC causes sodium excretion and potassium retention—see Pseudohypoaldosteronism Type I).
Diagnosis is suggested by the presence of hypertension in a young patient, particularly one with a positive family history. Low urine sodium (< 20 mEq, or 20 mmol/L), low plasma renin and aldosterone levels, and response to empiric treatment usually are considered sufficient to confirm the diagnosis. Definitive diagnosis can be achieved through genetic testing (see GeneTests for more information).