title: A high LDH to AST ratio helps to differentiate pregnancy-associated thrombotic thrombocytopenic purpura (TTP) from HELLP syndrome.
abstract: OBJECTIVE
  Differentiating between pre-eclampsia/HELLP syndrome and pregnancy-associated thrombotic thrombocytopenic purpura (TTP) is difficult but important in order to undertake timely and potentially life-saving plasma exchange (PEX) therapy for TTP recovery. We review our institutional experience with pregnancy-associated TTP and determine if the ratio of LDH to AST reliably distinguishes patients with TTP from those with HELLP syndrome.
  
  
  METHODS
  This is a retrospective case control study of all pregnant/puerperal patients with TTP from a single tertiary care center during 1986-2006. Laboratory findings in patients with TTP were compared to patients who met all criteria for class 1 or 2 HELLP syndrome within the first 24 hours of hospital admission during 2000-2007.
  
  
  RESULTS
  Thirteen pregnant (n = 10) or puerperal (n = 3) patients with TTP were identified; 11 cases were primary, 2 were recurrent. TTP laboratory findings included LDH to AST ratios of 77 ± 42.17; Patients with HELLP syndrome (N = 83) had significantly lower LDH to AST ratios of 20.04 ± 2.13. Based on an ROC analysis, an LDH/AST ratio ≥ 22.12 discriminates well between TTP and antenatal HELLP subjects (AUC = 0.99).
  
  
  CONCLUSIONS
  A high LDH to AST ratio >22.12 suggests that TTP is a more likely diagnosis than HELLP syndrome in the third trimester pregnant patient, presenting with findings that could be compatible with either diagnosis. In these circumstances, it is advisable to obtain hematology consultation and to consider PEX implementation.
authors: Department of Obstetrics & Gynecology, Division of Maternal-Fetal Medicine, University of Mississippi Medical Center, 2500 N State St., Jackson, MS 39216-4505, USA.
authors: Sharon D
authors: SD
authors: Keiser
authors: K W
authors: KW
authors: Boyd
authors: Jonathan F
authors: JF
authors: Rehberg
authors: Stephanie
authors: S
authors: Elkins
authors: Michelle Y
authors: MY
authors: Owens
authors: Imran
authors: I
authors: Sunesara
authors: James N
authors: JN
authors: Martin
mesh_terms: D000293:Adolescent; D000328:Adult; D001219:Aspartate Aminotransferases / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D003937:Diagnosis, Differential; D005260:Female; D017359:HELLP Syndrome / Q000175:diagnosis*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood*; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000175:diagnosis*; D011697:Purpura, Thrombotic Thrombocytopenic / Q000175:diagnosis*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007770:L-Lactate Dehydrogenase; D001219:Aspartate Aminotransferases