A 51-year-old white male with history of osteoarthritis, hypertension, and insomnia presented to the hospital with a 1-month history of fatigue, as well as a 1-week history of back pain, nausea, and dark urine. The patient worked as a construction contractor and lived with his wife. His family history was limited to his mother having diabetes. He was taking scheduled hydrochlorothiazide and celecoxib and taking zolpidem as needed. In addition, he was also taking a wide variety of nonprescribed nutritional supplements. At presentation, the patient had a decreased hemoglobin concentration of 3.5 g/dL [reference interval (RI),4 13.5–17.5 g/dL, with a baseline hemoglobin value of 12 g/dL obtained 6 months previously], a reticulocyte count of 1.2% (RI, 0.7%–3.2%), a total bilirubin value of 17.6 mg/dL (RI, 0.2–1.2 mg/dL), a direct bilirubin value of 4.6 mg/dL (RI, 0–0.5 mg/dL), a lactate dehydrogenase activity of 693 U/L (RI, 0–248 U/L), and a positive result in a direct antiglobulin test for IgG. His haptoglobin concentration was <30 mg/dL (RI, 48–224 mg/dL). A peripheral blood smear from the patient had 1 or 2 schistocytes and 1 or 2 spherocytes per high-power field, a typical platelet morphology, and hyperlobated neutrophils. He was transferred to an intensive care unit 2 days after presentation. Treatment with intravenous immunoglobulin and methylprednisone was initiated for immune hemolytic anemia. A bone marrow biopsy showed erythroid hyperplasia. His values for red blood cell folate, serum vitamin B12, C3, C4, rheumatoid factor, and red blood cell glucose-6-phosphate dehydrogenase activity were within their respective RIs, and the results of serum tests for antinuclear antibodies, cold agglutinin, and Mycoplasma antibodies were negative. He sequentially received rituximab, cyclophosphamide, and then plasmapheresis, in addition to methylprednisolone and intravenous immunoglobulin to treat his ongoing anemia. The patient was given transfusions of packed red blood cells …