Snapshot A 12-year-old girl is brought to the emergency department due to nausea and vomiting over the course of a few days. Her blood pressure is 140/103 mmHg. Laboratory testing is significant for hypokalemia, metabolic alkalosis, and undetectable levels of renin and aldosterone. Introduction Clinical definition a renal tubular disorder affecting the collecting tubules characterized by hypertension hypokalemia metabolic alkalosis also known as pseudohyperaldosteronism Epidemiology Incidence rare Demographics young children suspected if there is early onset hypertension may not be detected until adulthood Risk factors family history of early onset hypertension or hypokalemia may suggest Liddle’s Etiology Pathogenesis gain of function mutation involving the epithelial Na+ channel (ENaC) resulting in increased Na+ reabsorption in the collecting tubules this causes the lumen to be electronegative and causes a gradient that favors secretion of K+ into the lumen this results in decreased K+ mimics hyperaldosteronism (recall that aldosterone increases the number of open luminal Na+ channels) Genetics inheritance pattern autosomal dominant mutations chromosome 16p12 Presentation Symptoms triad presenting at a young age hypertension hypokalemia metabolic alkalosis Physical exam hypertension Studies Labs hypokalemia metabolic alkalosis ↓ aldosterone ↓ renin genetic testing most definitive diagnosis Differential Primary hyperaldosteronism Congenital adrenal hyperplasia Renal Tubular DefectsCategoryFanconi SyndromeBartter SyndromeGitelman SyndromeLiddle SyndromeDefect localizationProximal tubuleThick ascending loop of HenleDistal convoluted tubuleCollecting tubuleEtiologyWilson diseaseTyrosinemiaCystinosisMultiple myelomaGalactosemiaMitochondrial myopathiesMedicationsaminoglycosidescisplatinifosfamidevalproic acidHeavy metalsmercuryleadAutosomal recessive mutation involving the NKCC2 cotransporterAutosomal recessive mutationinvolving the NaCl cotransporterAutosomal dominant mutation leading to increased activity of ENaCFindingsHypophosphatemiaAminoaciduriaRenal glucosuriaTubular proteinuriaProximal renal tubular acidosisHypokalemiaHypochloremiaMetabolic alkalosisNormotensionElevated plasma renin levelHypokalemiaHypochloremiaMetabolic alkalosisHypomagnesemiaHypocalciuriaNormotensionHypertensionHypokalemiaMetabolic alkalosis Treatment Medical potassium-sparing diuretics indication for all with Liddle syndrome recall that both drugs directly blocks Na+ channels in the collecting tubules drugs amiloride triamterene Complications Cardiac arrhythmia due to hypokalemia Prognosis Very good with treatment