In addition to hemoglobin Köln, there have been cases of hereditary spherocytosis in which the hemoglobin concentration became exceptionally elevated after splenectomy.1 Such change is an immediate consequence of the procedure and not a late result. It is difficult to believe that the development of polycythemia vera two, three, and 11 years after splenectomy could be construed as "splenic hypofunction." It is under this topic that the authors of The Spleen include polycythemia as a late result of splenectomy, and it was on this point that my credulity foundered.
William H Crosby. Postsplenectomy Erythrocytosis, if not Polycythemia-Reply. Arch Intern Med. 1975;135(11):1524. doi:10.1001/archinte.1975.00330110114018