Cathy Lazarus, MD, Resident in Medicine, Jewish Hospital of St Louis: An obese, 54-year-old woman had an intestinal bypass procedure in 1975. An appendectomy and cholecystectomy were also performed at that time. Preoperatively, her weight stabilized to 155 kg. During the next four years she passed two to four diarrheal stools per day and lost 45 kg. In 1979 she noticed monthly episodes of "euphoria" and "drunkenness" during intervals when neither alcohol nor drugs were taken. Although the spells were disconcerting, they were short lived, and she failed to notify her physician. She was hospitalized at another institution in April 1980 because of an episode of ataxia and slurred speech. At that time, the blood pH was 7.34; Pco2, 27 mm Hg; Po2, 102 mm Hg; and bicarbonate ion levels, 14 mEq/L. Blood vitamin B12 levels were also low. She was subsequently treated with monthly vitamin B