Management of HIV Associated Thrombotic Thrombocytopenic Purpura.

Abstract

Thrombotic thrombocytopenic purpura (TTP) is a life threatening disorder characterised by thrombocytopenia and microangiopathic haemolytic anaemia associated with a deficiency in ADAMTS 13. Human Immunodeficiency Virus (HIV) remains an important infectious cause of TTP. We report the characteristics and treatment of patients presenting over a 6.5 year period to a tertiary referral centre. Cases: 9 patients, 8 female, 1 male, all heterosexual Africans. In 5 of the patients, TTP presentation was associated with the initial diagnosis of HIV. Only 1 patient was on highly active anti-retroviral therapy (HAART) at diagnosis. Median haemoglobin on admission was 6.4 (range 4.6–7.2) g/dl, platelet count-12 (range 5–53) X 109/L, lactate dehydrogenase (LDH) 1401 (range 914-2532) IU/L. In 6 patients there were neurological features at presentation, from headache, to transient ischaemic attacks and coma<INS cite=mailto:HCOHEN dateTime=2005-07-29T11:48>;</INS>6 patients had renal impairment, median creatinine 127 (range 63–418) μmol/L. Notably, HIV associated TTP was not a late onset disorder associated with poor CD 4 counts and poor prognosis. Median CD 4 counts were 170 (range 70–400) cells/μl, with a median viral load 74,400 copies/ml. ADAMTS 13 activity ranged from <5%–50% (normal range 66–126%) with no evidence of inhibitor by mixing studies using collagen binding assay. All patients received single volume plasma exchange<INS cite=mailto:HCOHEN dateTime=2005-07-29T11:50> </INS>(PEX) with cryosupernatant, median 8 (range 3-16) until remission and started HAART as soon as the diagnosis was made. Two patients received fresh frozen plasma (FFP) replacement for PEX for refractory TTP: one had coma and suboptimal treatment pre-referral, the second patient had an initial speedy recovery, but developed septicaemia. Two patients stopped their anti-retroviral therapy and had a TTP relapse with<INS cite=mailto:HCOHEN dateTime=2005-07-29T11:51>in</INS> 3 months. However, recommencement of HAART plus 3 and 6 PEX's respectively was associated with remission. Six of the patients remain in remission from TTP at 6–74 months; 2 were lost to follow-up and 1 died 18 months later from renal failure, unrelated to TTP. These data suggest HIV status should be checked in all patients presenting with acute TTP as it accounted for 12.5% of all acute TTP admissions in our cohort. All HIV associated TTP patients were black African heterosexual<INS cite=mailto:HCOHEN dateTime=2005-07-29T11:56>s</INS>. Treatment with PEX and HAART was associated with speedy remission of TTP. In patients who stopped HAART, TTP relapsed within 3 months. The abscence of antibody to ADAMTS 13 suggests a possible direct effect of the retrovirus on endothelium. With HAART and a decrease in viral load, ADAMTS 13 activity increases as patients achieve remission.