A high LDH to AST ratio helps to differentiate pregnancy-associated thrombotic thrombocytopenic purpura (TTP) from HELLP syndrome

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. Study design: 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 = 8...