Increased platelet activation in renal transplant patients

Backgroun d: Patients with functioning renal transplants are at risk of graft thrombosis in the postoperative period, an d of fistula thrombosis and other thrombotic events thereafter. Investigation and therapeutic m anipulation of haemostasis in these patients offers a means to counter this throm botic tendency. M ethods: Platelet aggregation in whole blood, plasma von W illebrand factor and plasma fibrinogen levels were m easured in 32 stable renal transplant patients (creatinine 4 m onths) an d in 32 age, sex and sm oking-habit m atched norm al controls. Results: In both patient and control groups, seven patients were sm okers and the rem aining 25 were non-sm okers. There was no significant difference in age between patients and controls [patients, m edian: 39 (20 ± 64) years; controls: 38 (24 ± 60) years]. Sponta neous platelet aggregation was significantly higher in the patients at all tim e points studied [30 s ± 6 min; at 4 m in: patients m edian (interquartile range) 19.4 (11.3 ± 27.3)% ; controls, 8.0 (5.1± 15.0)% , P < 0.0005]. ADP-induced aggregation was also increased at a concentration range of 0.1± 3 m M (at 1 m M , 1 min, patients median (interquartile range) was 52.4 (30.5 ± 70.0)% ; controls was 16.5 (1.4 ± 31.4)% , P < 0.0001). Transplant patients had significantly higher von W illebrand factor and fibrinogen levels com pared with the controls (von W illebrand factor, patients median (range): 158 (13 ± 269)% ; controls: 85 (43 ± 223)% , P < 0.00001; fibrinogen, patients: 3.29 (2.12 ± 7.39) g/litre; controls: 2.81 (1.84 ± 4.65) g/litre, P < 0.0002) . C onclusion: Patients with stable renal transplants have in vitro evidence of enhan ced platelet activation, and increased plasm a von W illebrand factor and fibrinogen levels.