Platelet aggregation and physiological anticoagulants in sickle-cell disease.

During the period January 2002-December 2004, we assessed 30 sickle-cell anaemia patients admitted to hospital in Al Khobar with vaso-occlusive crisis for levels of antithrombin (AT) III, protein C (PC) and protein S (PS). We also did platelet aggregation studies. Steady state levels were assessed during follow-up and compared with 36 adult controls. Levels of PC, PS and AT III in the control group were significantly higher than in those in vaso-occlusive crisis and those in steady state (P < 0.001). There was a statistically significant difference between controls and patients for all platelet aggregation factors except adrenaline. There was no significant difference between the levels of PC, PS, AT III and platelet aggregation variables in patients in the steady state and in vaso-occlusive crisis.