[A case of Gitelman's syndrome presenting with the hypokalemic periodic paralysis]

We report a rare case of Gitelman's syndrome (GS) presenting with the hypokalemic periodic paralysis. A 27-year-old man was admitted to our hospital because of transient weakness of the limbs. Past history was unremarkable, including the delivery and early developmental milestones, except for a transient limb weakness 7 times since the age of 15 years. The blood pressure was 140/90 mmHg. The physical examinations were unremarkable. Neurologically, the patient was fully oriented. The cranial-nerve functions were intact. Manual muscle tests revealed 1/5 weakness in his neck and extremities. Sensation was normal in all modalities. The deep tendon reflexes were present but decreased mildly. Laboratory tests showed hypokalemia (1.9 mEq/l), hypomagnesemia (1.8 mEq/l), and hypocalciuria (40.0 mg/dl). Plasma rennin activity and aldosterone concentration were elevated. The molar ratio of urinary calcium/creatinine was 0.11 (< 0.2). Arterial blood gas showed mild metabolic alkalosis with respiratory compensation. Because of these data, the diagnosis of GS was made. Gene mutations in the renal thiazide sensitive Na-Cl cotransporter (TSC) have already been shown to cause GS. Although we searched for gene mutation of TSC, none of 25 mutations in 18 out of 26 exons which had been previously reported were found. This is the first report of Gitelman's syndrome presenting with the hypokalemic periodic paralysis in Japan.