A case of leptospirosis presenting as TTP
Authors: Daire K. Quinn, John Quinn, Peter J. Conlon, Philip T. Murphy
Journal: American Journal of Hematology (2013)

In their recent article, Booth et al. describe a number of cases of systemic infection with reduced a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) activity, whose presenting clinical features mimicked thrombotic thrombocytopenic purpura (TTP) 1. In the past, a small number of cases of leptospirosis have been reported to be associated with TTP 2-4. We describe a further such case of leptospirosis, with presenting features suggestive of TTP and report, for the first time, an associated reduction in ADAMTS activity. A previously well 49-year-old Caucasian male was hospitalized with 11-day history of general malaise and 5 days of increasingly severe lower limb muscle pain. On physical examination, he was jaundiced and had generalized tenderness of his legs. He had low grade fevers with a maximum temperature of 37.8°C. There was no history of headache or rigors. Complete blood count (CBC) revealed hemoglobin of 12.9 g/dl with a white cell count of 9.8 × 109/l and platelets 21 × 109/l. Both kidney and liver functions were shown to be deranged, with urea of 35.5 mmol/l, creatinine of 698 µmol/l, bilirubin of 198 µmol/l, alanine aminotransferase of 244 IU/l, and alkaline phosphatase of 180 IU/l, and hypoalbuminemia of 30 g/l. Serum lactate dehydrogenase was 1,677 IU/l. Blood film examination showed severe thrombocytopenia and fragmented red cells. In light of this patient's acute kidney injury, thrombocytopenia, and anemia, a working diagnosis of TTP was made and subsequently daily therapeutic plasma exchange (TPE) and high dose intravenous corticosteroids were commenced. Due to worsening renal function, with a serum creatinine of 759 µmol/l, and the onset of oliguria on day 2 of admission, hemodialysis was initiated. On day 3 of TPE and high dose IV corticosteroid treatment, a CBC revealed no improvement in the thrombocytopenia, with a platelet count of 8 ×109/l. There was still a marked transaminitis which had not improved since admission. Closer questioning revealed that the patient had potentially been exposed to vermin three weeks previously while working outdoors. In light of this new information, leptospirosis serology was undertaken and antibiotic treatment for the possible leptospiral infection was commenced with a course of intravenous (IV) ceftriaxone. Within the following 24 hr, the patient's clinical condition and abnormal blood test results began to improve, with CBC and renal indices returning to normal values and markedly improved liver blood tests by day 16 of admission. Serological testing showed a positive microscopic agglutination test for leptospira and ELISA-testing demonstrated the presence of anti-leptospira IgM. Subsequently, a 14-day course of IV antibiotic treatment was completed, hemodialysis was discontinued, and TPE was stopped after 5 days. ADAMTS13 activity, sent on admission, was reduced at 43% (60–123%). This patient presented with features suggestive of TTP but failed to respond to plasma exchange. Once a diagnosis of leptospirosis was suspected and appropriate antibiotics started, the patient made a rapid and complete recovery. In retrospect, the disproportionally abnormal liver blood tests at presentation were atypical for TTP and might have triggered a more prompt introduction of antibiotics for suspected leptospirosis. We certainly agree with the conclusions of Booth et al. that, patients with systemic infection who present with clinical features suggestive of TTP, timely detection and treatment of such infections may avoid inappropriate continuation of plasma exchange. Daire K. Quinn,1 John Quinn,1 Peter J. Conlon,2 Philip T. Murphy1 1Department of Haematology/Oncology, Beaumont Hospital, Dublin 9, Ireland 2Department of Renal Medicine, Beaumont Hospital, Dublin 9, Ireland