A 68-year-old woman was admitted to the hospital because of impaired renal function. One month earlier, she had had difficulty breathing and had felt as though she had a fever; she went to another hospital, where nebulizers were prescribed, and her dyspnea improved. Two weeks later, malaise and a sensation of chilliness developed, with diffuse pains in the arms and legs, which prompted her to take two or three tablets of ibuprofen every four to five hours for two weeks, although the medication was only minimally effective. Ten days before admission, pruritus developed. She consulted a physician, who found that her temperature was 37.8°C and prescribed cetirizine.Four days later, she consulted her customary physician. The urine was ++ for protein; the sediment contained 50 to 100 white cells and moderate numbers of tubular cells. The urea nitrogen level was 20 mg per deciliter (7.1 mmol per liter), and the creatinine level 1.5 mg per deciliter (132.6 µmol per liter), although previously, the creatinine level had been around 0.8 mg per deciliter (70.7 µmol per liter). She was advised to discontinue taking ibuprofen and to return for follow-up, but on the day of admission she vomited twice, felt extremely fatigued, continued to have malaise, and produced less urine than usual. She was admitted to the hospital.The patient had a history of hypertension. Six years before admission, she had had an abdominal hysterectomy with incidental appendectomy because of endometrial carcinoma. She had smoked one pack of cigarettes daily for 20 years but had stopped smoking 30 years before admission. She consumed wine with dinner. She resided with her husband and had several children, one of whom had multiple sclerosis. Her medications were hydrochlorothiazide, conjugated equine estrogens, aspirin, and a multivitamin tablet, as well as ibuprofen. She had no recurrence of dyspnea or fever, and she reported not having had frank chills, chest pain, abdominal pain, diarrhea, dysuria, polyuria, arthralgia, or rash or having recently traveled.The temperature was 37.3°C, the pulse 66 beats per minute, and the respiratory rate 20 breaths per minute. The blood pressure was 110/75 mm Hg. The oxygen saturation was 99 percent while the patient breathed ambient air. On physical examination, there was no rash or lymphadenopathy, and no petechiae were found. The jugular venous pressure was 7 cm of blood. The lungs were clear, and the heart sounds were normal. The abdomen was unremarkable. There was trace peripheral edema, and the pulses at the hands and feet were intact. case records of the massachusetts general hospital 2057 * To convert the values for phosphorus to millimoles per liter, multiply by 0.3229. To convert the values for cholesterol to millimoles per liter, multiply by 0.02586. To convert the value for triglycerides to millimoles per liter, multiply by 0.01129. To convert the value for magnesium to milliequivalents per liter, divide by 0.5. To convert the values for urea nitrogen to millimoles per liter, multiply by 0.357. To convert ...