What is Barth syndrome? Barth syndrome. It is a hypokalemic alkalosis with increased plasma renin and aldosterone but normal blood pressure, characterized by hyperplasia and hypertrophy of the paraglomerular apparatus. Early manifestations include polyuria, irritable thirst, constipation, anorexia and vomiting. It is commonly seen in children under 5 years of age and is a clinical syndrome due to mutations in ion channel genes. The clinical manifestations are also complex and varied. However, hypokalemia predominates, while differing by slow growth, muscle weakness, and wasting. In adults, it is also mainly characterized by muscle weakness, in fact, fatigue, twitching, abnormal sensation, polyuria and constipation. Some patients are diagnosed without these symptoms but with other symptoms when they visit the doctor.