Approximately 7 weeks before the current evaluation, he was seen in the outpatientclinic at this hospital. The vital signs were normal. Urticarial lesions werepresent on the arms, trunk, and hips, and petechial lesions were present on the legs.The serum level of sodium was 131 mmol per liter (reference range, 135 to 146),and the level of chloride was 96 mmol per liter (reference range, 99 to 111). Measurementsof other electrolytes, calcium, glucose, iron, total iron-binding capacity,thyrotropin, and cortisol (measured in the afternoon) were normal. Testing for antibodiesto Borrelia burgdorferi was negative; other laboratory-test results are shownin Table 1. Blood cultures were sterile.