Absence of a Spleen
A splenectomy is the surgical removal of the spleen. It is one of the major causes [10] of reactive thrombocytosis. The spleen plays a huge role in the production, removal and storage of blood cells. It also helps in fighting infections. Some amount of platelets is always stored in the spleen. If the spleen is removed, thrombocytosis usually happens after.
Thrombocytosis immediately following spleen removal may be quite severe and result in the formation of blood clots. This only happens in a small number of cases. Most cases of thrombocytosis caused by spleen removal are harmless and get better on their own after a while.