Dr. Arthur Schneider, Junior Assistant Resident in Medicine, the Jewish Hospital of St. Louis, and Assistant in Medicine, Washington University School of Medicine: A 66-year-old white woman was admitted to Jewish Hospital with a two-day history of abdominal pain, vomiting of bilious material, and diarrhea. There was no previous history of weight gain, cold intolerance, or constipation. In the past few months she had had some drowsiness and a gradual decrease in mental acuity. On admission, the blood pressure was 130/ 80 mm Hg, pulse rate was 76 beats per minute, and temperature was 98 F (35.0 C). The voice was deeply pitched and hoarse, the skin was dry, and the scalp hair was coarse. Rales were heard at the bases of both lungs. Examination of the abdomen revealed diffuse involuntary rigidity, rebound tenderness, and high-pitched, rushing bowel sounds. Deep tendon reflexes were abnormally delayed and symmetrical in response.