CHANGES IN COAGULATION AND FIBRINOLYSIS IN PATIENTS WITH SICKLE-CELL DISEASE COMPARED WITH HEALTHY BLACK CONTROLS

Seventeen parameters of coagulation and fibrinolysis were measured in 33 patients with sickle cell disease; 30 were tested in steady state (SS) and 19 in crisis (Cr). There were 16 patients in both groups. The same parameters were measured in 16 controls of similar ethnic origin (Black controls; BC) and 20 Caucasian controls (CC), all with HbA only. Highly significant differences (P < 0.001) between Black and Caucasian control groups were noted for: fibrinogen, fibrinopeptide-A (FPA), beta-thromboglobulin (beta TG) and D-dimer. Significant differences (P < 0.03) in plasminogen activator inhibitor (PAI) and functional antithrombin III levels were also noted. Results of the sickle cell patients were therefore compared with those of the Black controls. Sickle cell patients in SS had raised vWf compared with BC, which increased further during Cr (P = 0.001), but showed no significant increase in fibrinogen. Functional protein C was reduced in SS (P = 0.004) but with no further fall in Cr, while free protein S was normal in SS but reduced in Cr (P = 0.02). Total protein S and ATIII were normal in SS and Cr. FPA and beta TG were not significantly raised in SS or Cr compared with BC. There were, however, highly significant increases in D-dimer and thrombin-antithrombin complexes (TAT) in both SS and Cr compared with BC (P < 0.001 for SS and Cr vs BC). Thus significant activation of coagulation with consequent increase in fibrinolysis occurs during both the sickle cell crisis and in the steady state. Significantly lower levels of functional protein C and free protein S were also observed in the sickle cell patients. No obvious differences were observed in steady state values for any of the measured parameters between patients who had frequent crises and those who had crises only rarely. It is important to use controls of appropriate ethnic origin.