Platelet count profiles major versus minor procedures and platelet count range of all patients with major surgical procedures in relation to the platelet count profile of the 5 HIT patients. (A) Platelet count profiles in patients after major versus minor procedures. Solid line indicates major surgery, platelet count mean ± SD (hatched area). Dotted lines indicate minor surgery, platelet count mean (bold line) ± SD. Platelet count nadir (P < .001) as well as profiles from on day 5 (P < .001) differ significantly between the 2 groups. Platelet count decrease was greater after major surgery versus minor surgery (nadir day 3; 193 000/mm³, mean ± 65.1 vs 210 500/mm³ mean ± 56.1; P < .001) with a greater reactive platelet count increase (P < .001): > 50% (48.3% vs 15.6%); > 30% to 49% (18.4% vs 14.3%); and < 30% (33.3% vs 72.6%). (B) Platelet count range of all patients with major procedures (platelet count mean [bold line] ± SD [hatched area]) in relation to the platelet count profile of the 5 HIT patients (black, gray, and dotted lines). *Time of diagnosis of thrombosis.