Idiopathic Thrombocytopenic Purpura (ITP)
- Adult Chronic Immune Thrombocytopenic Purpura

Once the antibodies attach to the platelet, the platelet is tagged as abnormal. Once tagged as abnormal the platelet is trapped in the spleen causing the blood platelet count to drop. This function of the spleen is normal. The abnormality in ITP is the body's immune system that is incorrectly reacting to the normal platelets.

Initial treatments are medical and involve administration of various medications to suppress the immune system and/or reduce the spleen's ability to remove platelets from the blood. If the platelet count can be supported a portion of patients can go into remission. (43% - Blood 99:1922, 2002)

For patients who do not have an adequate sustained response to medical treatment, or seem unlikely to attain remission after prolonged medical treatments (12 months?), or who have adverse effects from medical therapy, splenectomy (removal of the spleen) is usually recommended.

Splenectomy gives the highest cure rate of all treatments. When the results of several large studies were combined, splenectomy resulted in a permanent complete response (normal platelet count on no treatment) in 59.9% of 667 patients; 12.3% of these patients achieved a stable partial response (safe platelet counts on no treatment). Therefore, 72.2% of the patients required no additional treatment for their ITP after splenectomy. There are other studies, however, that show a poorer long term response rate in the 40-50% range.

At present, there is no way to predict, prior to surgery, who will respond to splenectomy. One article suggested that patients, whose platelet count increases after treatment with intravenous gammaglobulin, are more likely to respond to splenectomy (Law C, Marcaccio M, Tam P et al. New England Journal of Medicine 336:1494, 1997). However, other groups could not confirm this result.

After surgery the platelet count increases rapidly with normal counts appearing within 2 weeks in most responding patients. Recurrent thrombocytopenia, after an initial response, occurred in 12.3% of the above patients, usually within a few months after surgery. Youth, a short disease duration and an increase in the platelet count to greater than 400-600,000 after surgery are good prognostic signs.

Some ITP patients who relapse at a later time after surgery have an accessory spleen (small amounts of splenic tissue that are not connected to the main organ which may not have been removed at the time of surgery). All patients who relapse after surgery should be evaluated for an accessory spleen. If present, these should be removed unless there is some medical reason that prevents surgery.

Platelet Disorder Support Association - Very comprehensive site, patients newsletter and discussion group.
The Scripps Research Institute - Chronic ITP site - A bit more technical and directed more towards health care professionals.