A case report of a young boy with low renin and high aldosterone levels induced by Liddle syndrome who was previously misdiagnosed with primary aldosteronism.

OBJECTIVES: Liddle syndrome is an autosomal dominant hereditary disease caused by a single gene mutation. Typical clinical manifestations are early-onset hypertension and hypokalemia.

CASE PRESENTATION: This report describes a 17-year-old male with hypertension and hypokalemia. We performed Captopril inhibition and postural stimulation test to diagnose and type primary aldosteronism. The plasma renin activity was consistently low, and aldosterone levels were high, hence the patient was initially diagnosed with primary aldosteronism. After genetic analysis, a diagnosis of Liddle syndrome was made due to the presence of a p. Pro617Ser mutation in the SCNN1B gene. After diagnosis, the patient was prescribed one tablet of amiloride twice a day. The patient's blood pressure (average in 120-135/70-80 mmHg) and serum potassium levels (3.6-4.0 mmol/L) returned to normal and was well-controlled after treatment.

CONCLUSIONS: Adolescent hypertension may be secondary to underlying medical conditions affecting the heart, kidneys, or endocrine system or primary with no known underlying disease process. Although in an adolescent with hypertension, hyperaldosteronism, and low plasma renin activity, the initial diagnosis suggested primary hyperaldosteronism, the failure of aldosterone receptor antagonist's therapy led to the diagnosis of Liddle syndrome. Increased aldosterone levels should always be evaluated with caution before a definitive diagnosis to prevent misdiagnosis. Genetic testing is the gold standard for the diagnosis of Liddle syndrome. Early diagnosis and early precise treatment can restore normal blood pressure and prevent severe sequelae of chronic hypertension in patients.