THROMBOTIC THROMBOCYTOPENIC PURPURA-HEMOLYTIC UREMIC SYNDROME (TTP-HUS) AFTER A SINGLE DOSE OF QUININE. J. Lee 1 , M. Krasnoff 1 ; 1 Dartmouth Hitchcock Medical Center, Lebanon, NH (Tracking ID #74449) LEARNING OBJECTIVES: 1. Identify a potentially fatal complication of a commonly prescribed therapy for nocturnal leg cramps. 2. Recognize quinine as the most common cause of drug-associated TTP-HUS. CASE INFORMATION: The patient is a 66 year old previously healthy female who presented to the emergency department with the acute onset of nausea, vomiting, abdominal pain, diarrhea, and disorientation 2.5 hours after taking a single dose of 260 mg of quinine for nocturnal leg cramps. Over the next few hours, she developed severe hypotension, requiring pressors. Labs were notable for WBC 3.6 Plt 123,000 Bun 25 Cr 1.9 T bili 1.7 PTT 75 PT > 100. A CT scan of the abdomen and pelvis was unremarkable. The patient was admitted to the ICU with a presumed diagnosis of sepsis of unclear etiology; she was started empirically on IV ampicillin/sulbactam. Over the next few days, the patient developed microangiopathic hemolytic anemia, severe thrombocytopenia (Plt 12,000), and acute renal failure (Cr 8.4). Cultures of sputum, urine and blood showed no growth. Her clinical diagnosis was felt to be TTP-HUS; her antibiotics were stopped and she was begun on daily plasmapheresis. Dialysis was instituted. After two weeks of therapy, the patient's anemia, thrombocytopenia, renal failure, disorientation, and coagulopathy were all improving or resolved. An adverse event report was sent to FDA MedWatch. IMPLICATIONS/DISCUSSION: Nocturnal leg cramping is a common complaint encountered in the primary care setting. Despite quinine being frequently prescribed, its potential for severe adverse reactions is largely underrecognized. Quinine is the most common cause of drug-associated TTP-HUS. Common presenting symptoms include the acute onset of abdominal pain, nausea, vomiting, diarrhea, fevers and chills. The symptoms usually begin abruptly, several hours after the ingestion of quinine. A single tablet is sufficient to cause TTP-HUS. In addition to the expected findings of TTP-HUS, low-grade DIC and leukopenia can also be seen. The mechanism of quinine-associated TTP-HUS is presumed to be caused by drug-dependent antibodies. Treatment involves avoidance of quinine exposure, plasmapheresis and supportive therapy. While available by prescription, quinine is also found in beverages, such as quinine water, tonic water, and gin and tonic. In addition, there is an extensive list of herbal remedies containing quinine including cinchona tree, peruvian bark, and china bark. Physicians should carefully question any patient with TTP-HUS for quinine exposure, especially since patients may not report it among their medications. In addition, physicians need to counsel patients regarding future avoidance of all quinine-containing compounds, since repeat ingestion of quinine may cause relapse of TTP-HUS.