A low platelet count is termed thrombocytopenia. As the platelet count falls, bruising, tiny red bleeding points in the skin called petechiae (especially on the lower legs), nosebleeds, or other bleeding may occur. Although there are many possible causes of thrombocytopenia, in lupus it is almost always due to antibodies. A low platelet count may briefly be aggravated by infection. Whereas thrombocytopenia is common in lupus, only occasionally does serious bleeding result. On rare occasions, a person with lupus may have antibodies against both red blood cells and platelets.
When excess blood loss is combined with thrombocytopenia (a low platelet count), this can result in a condition named thrombotic thrombocytopenic purpura (TTP).