Revascularização miocárdica com circulação extracorpórea; aspectos bioquímicos, hormonais e celularesOn-pump coronary artery bypass graft surgery: biochemical, hormonal and cellular features This study was carried out at Federal University of São Paulo, Discipline of Cardiovascular Surgery, São Paulo, SP, Brazil. Methods: Eighteen patients underwent on-pump CABG surgery. Mean time of CPB was 80.3 minutes. Hormonal, biochemical and cellular measurements were taken in some time points -preoperatively, immediately after coming off CPB, 24 and 48 hours postoperatively. Friedman and Wilcoxon tests were applied based on significance level of 5%.Results: There was activation and significant elevation of total leukocytes and neutrophils count over CPB, remaining this way up to 48 hours postoperatively. Total platelets count, in turn, was marked by relevant reduction immediately after coming off CPB as well as in two postoperative time points. Serum levels of total proteins and albumin, immediately after coming off CPB and also in two postoperative time points, were significantly decreased comparing with preoperative status. There was remarkable reduction of total T3, free T3 and total T4 particularly up to first 24 hours postoperatively.Conclusion: In on-pump CABG surgery, inflammatory effects encompass activation of total leukocytes, neutrophils and platelets, reduction of serum level of total proteins and albumin and decreased thyroid hormones levels, especially within first postoperative 24 hours.