Changes in the natural anticoagulants following bone marrow transplantation.

The natural anticoagulants, protein C, protein S and antithrombin, were measured in 21 patients following bone marrow transplantation (BMT). The patients were divided into two groups, those with normal protein C concentration post-BMT and those with significantly reduced protein C concentrations; 12 cases fell into the second group. In addition there was an associated fall in protein S in this group of patients. In spite of the presumed hypercoagulable state only one patient developed overt veno-occlusive disease (VOD) of the liver and no other thrombotic events occurred. The fall in protein C and protein S was coincident with the peak incidence of VOD and is likely to be a contributing factor to the genesis of this condition. Only protein S measured pre-BMT was of predictive value in identifying patients likely to develop reduced levels of these anticoagulants post-BMT. Age, sex, diagnosis, type of conditioning and the pre-BMT measurement of protein C and antithrombin had no predictive value.