Thrombin generation in morbid obesity: significant reduction after weight loss

Summary. Background: Patients with morbid obesity (MO; body mass index > 40 kg m^?2) suffer from an increased risk of cardiovascular disease, stroke, venous thromboembolism and all‐cause mortality. Objectives: Because weight loss by bariatric surgery reduces cardiovascular and all‐cause mortality, we hypothesized that the plasmatic clotting system might be involved in cardiovascular risk. Patients/Methods: Thirty‐six MO patients [mean age 42 (±13) years; 29 female) were investigated before and 2 years after bariatric surgery. Thrombin generation was measured with a commercially available assay (Technothrombin‐TGA,Technoclone). Metabolic parameters and parameters of the hemostatic system, such as tissue factor (TF), TF pathway inhibitor (TFPI), plasminogen activator inhibitor‐1 (PAI‐1) and prothrombinfragment 1.2 (F1.2), were determined. To investigate associations of changing parameters, deltas were calculated. Results: Metabolic parameters improved with a mean weight loss of 41 (±19) kg. Postoperatively, the lag phase was significantly extended compared with preoperative values [median (25th–75th percentile), 7 (4–12) vs. 12 (7–19) min, P = 0.005]. Peak thrombin decreased after weight loss from 345 (232–455) to 282 (111–388) nm (P = 0.015) and the area under the curve from 3962 (3432–5023) to 3227 (2202–4030) nm thrombin (P < 0.001). TF, PAI‐1 and F1.2 significantly decreased after weight loss. Analyses of the deltas showed a significant correlation between peak thrombin and total cholesterol (r = 0.50), triglycerides (r = 0.46) and HbA1c (r = 0.55). Moreover, an inverse correlation was found between insulin resistance and the lag phase (r = ?0.46). Conclusion: Thrombin generation, a marker of the overall coagulation potential, decreased significantly with weight reduction. This might, at least in part, explain the decreased risk of cardiovascular disease after bariatric surgery.