Liddle syndrome is a rare autosomal dominant disorder of renal epithelial transport Introduction to Renal Transport Abnormalities Many substances are secreted or reabsorbed in the renal tubule system, including electrolytes, protons, bicarbonate molecules, glucose, uric acid, amino acids, and free water. Dysfunction of... read more that clinically resembles primary aldosteronism Primary Aldosteronism Primary aldosteronism is aldosteronism caused by autonomous production of aldosterone by the adrenal cortex (due to hyperplasia, adenoma, or carcinoma). Symptoms and signs include episodic weakness... read more , 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 Pseudohypoaldosteronism Type I Pseudohypoaldosteronism type I is a group of rare hereditary disorders that cause the kidneys to retain too much potassium but excrete too much sodium and water, leading to hypotension. Symptoms... read more ).
Patients with Liddle syndrome present at age < 35 years. Hypertension and symptoms and signs of hypokalemia Hypokalemia Hypokalemia is serum potassium concentration < 3.5 mEq/L (< 3.5 mmol/L) caused by a deficit in total body potassium stores or abnormal movement of potassium into cells. The most common... read more and metabolic alkalosis Symptoms and Signs Metabolic alkalosis is primary increase in bicarbonate (HCO3−) with or without compensatory increase in carbon dioxide partial pressure (Pco2); pH may be high or nearly normal. Common... read more occur.
Diagnosis of Liddle Syndrome
Urine sodium level
Plasma renin and aldosterone levels
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) .
Treatment of Liddle Syndrome
Triamterene or amiloride
Triamterene 100 to 200 mg orally twice/day and amiloride 5 to 20 mg orally once/day are both effective because they close sodium channels. Spironolactone is ineffective.
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GTR: Genetic Testing Registry: This central location for genetic test data includes information on the purpose, validity, and usefulness of those tests, which are grouped by helpful search categories (eg, human tests, microbe tests, conditions/phenotypes).
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