Abstract
Gitelman syndrome （GS） is a genetic disorder caused by mutations in the gene, which codes for the Na-Cl cotransporter on the distal convoluted tubule. GS leads to hypokalemia, metabolic acidosis, hyperreninemia, hyperaldosteronemia, short stature, seizure, and tetany. We describe two siblings in whom incidental hypokalemia detection was a clue towards GS diagnosis. 【Patient 1 （elder brother）】 A generally healthy 10-year-old boy presented to his primary care physician with a cough, which subsequently worsened, necessitating admission to our hospital. Examination revealed pneumonia, hypokalemia, and long QT. His blood pressure was normal; however, plasma renin activity and aldosterone concentrations were increased. Oral potassium was administered, which improved his hypokalemia and long QT. 【Patient 2 （younger brother）】 A generally healthy 9-year-old boy presented with fever and cough. Antibiotics were administered for Mycoplasma pneumonia, and blood tests revealed hypokalemia. The patient’s condition did not improve with the aforementioned treatment, and he was admitted to our hospital. He received oral potassium therapy and improved thereafter. The patients described in this report were siblings and both presented with hypokalemia, suggesting GS. Genetic analysis of revealed two heterozygous mutations （c.179C＞T and c.781C＞T） in both patients. Incidentally detected blood test abnormalities may provide useful clues to diagnose GS. Clinicians should consider GS in the differential diagnosis of patients presenting with hypokalemia.
