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Liddle syndrome is a rare hereditary disorder involving increased activity of the epithelial Na channel (ENaC) which causes the kidneys to excrete K but retain too much Na and water, leading to hypertension. Symptoms are of hypertension, fluid retention, and metabolic alkalosis. Diagnosis is through measurement of urinary electrolytes. K-sparing diuretics provide the best treatment.
Liddle syndrome is a rare autosomal dominant disorder of renal epithelial transport that clinically resembles primary aldosteronism (see Adrenal Disorders: Primary Aldosteronism), with hypertension and hypokalemic metabolic alkalosis but without elevated plasma renin or aldosterone levels. The syndrome results from an inherently increased activity of the epithelial Na channels (ENaC), located on the luminal membrane, which accelerates Na resorption and K secretion in the collecting tubule (underactivity of ENaC causes Na excretion and K retention, see Renal Transport Abnormalities: Pseudohypoaldosteronism Type I).
Patients with Liddle syndrome present at age < 35 yr. Hypertension and symptoms and signs of hypokalemia (see Electrolyte Disorders: Hypokalemia) and metabolic alkalosis occur.
Diagnosis
Diagnosis is suggested by the presence of hypertension in a young patient, particularly one with a positive family history. Low urine Na (< 20 mEq), normal 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).
Treatment
Triamterene 100 to 200 mg po bid and amiloride 5 to 20 mg po once/day are both effective because they close Na channels. Spironolactone is ineffective.
Last full review/revision April 2013 by James I. McMillan, MD
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