title: ADAMTS13 activity levels in patients with human immunodeficiency virus-associated thrombotic microangiopathy and profound CD4 deficiency.
abstract: BACKGROUND
  Thrombotic microangiopathy (TMA) encompasses a number of disorders with hemolytic anemia and thrombocytopenia, including thrombotic thrombocytopenic purpura (TTP). A deficiency in ADAMTS13 enzyme levels, along with an inhibitory antibody, is found in most patients with idiopathic TTP. Patients with human immunodeficiency virus (HIV) infection can have a TTP-like illness; however, it appears to have a different etiology.
  
  
  METHODS
  A retrospective review of patients who had an ADAMTS13 activity level performed from 2005 through 2007 was completed. Patients with a diagnosis of HIV infection with TMA were investigated.
  
  
  RESULTS
  Two patients were identified. Case 1: a 47-year-old man with HIV infection and a CD4 count <10/microL presented with altered mental status, pneumonia, acute renal failure, thrombocytopenia, and anemia. The ADAMTS13 level was 71%. He was treated with plasma infusion. Two days after admission, he expired because of respiratory distress syndrome and metabolic lactic acidosis. Case 2: a 39-year-old man with HIV infection and a CD4 count of 9/microL presented with chest pain, acute renal failure, thrombocytopenia, and anemia. The ADAMTS13 level was 65%. He received multiple units of fresh frozen plasma without significant improvement in his platelet count. Six days after admission, the patient began highly active antiretroviral therapy, which resulted in a rapid increase in his platelet count.
  
  
  CONCLUSIONS
  HIV-associated TMA is postulated to have a different pathophysiology than idiopathic TTP. This study supports that assumption because both patients exhibited many of the classic findings of TTP but did not have a deficiency of ADAMTS13.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of North Carolina Hospitals, Chapel Hill, North Carolina, USA. yapark@unch.unc.edu
authors.forename: Yara A
authors.initials: YA
authors.lastname: Park
authors.forename: Shauna N
authors.initials: SN
authors.lastname: Hay
authors.forename: Mark E
authors.initials: ME
authors.lastname: Brecher
mesh_terms: D051722:ADAM Proteins / Q000097:blood*; D000071120:ADAMTS13 Protein; D000328:Adult; D000743:Anemia, Hemolytic / Q000209:etiology / Q000821:virology*; D015704:CD4 Antigens; D003937:Diagnosis, Differential; D006678:HIV; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011697:Purpura, Thrombotic Thrombocytopenic / Q000175:diagnosis; D012189:Retrospective Studies; D013921:Thrombocytopenia / Q000175:diagnosis / Q000209:etiology / Q000821:virology*
chemical_list: D015704:CD4 Antigens; D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human