Effects of strenuous exercise on blood coagulation activity in sickle cell trait carriers.

We compared routine coagulation markers in six sickle cell trait carriers ((SCT, or AS hemoglobinopathy)--the heterozygous form of sickle cell anemia) and six subjects with normal hemoglobin before and after a prolonged and intense exercise. Blood was sampled at rest and at the end of the entire exercise test to measure coagulation markers (prothrombin time, activated partial thromboplastin time, plasma fibrinogen and antithrombin III activity), hematocrit (Hct) and yield stress (tau(y)). Results obtained at the end of exercise were corrected by the percent change in plasma volume. Blood coagulation markers, Hct and tau(y) were not different between the two groups at rest. Exercise did not change prothrombin time, antithrombin III activity and plasma fibrinogen, decreased activated partial thromboplastin time and increased Hct and tau(y) in the two groups. These parameters were not significantly different between the two groups at the end of exercise, except for plasma fibrinogen which was slightly higher in SCT carriers but in the normal range values. The results have been discussed in relation with some cases of exercise-related sudden death in SCT carriers, reported in several studies. Therefore our results show that the increased risk for clinical complications in certain SCT carriers during exercise seems to be unrelated to higher blood coagulation activity.