|Posted on November 20, 2011 at 3:37 PM||comments ()|
by Subhuti Dharmananda, Ph.D., Director, Institute for Traditional Medicine, Portland, Oregon
Idiopathic Thrombocytopenic Purpura (ITP) is a somewhat archaic term for a condition of low platelets (thrombocytes). Idiopathic means that the cause is unknown; with advances in modern technology, a substantial amount has been learned about the causes. While one may not be able to definitively point to all the causative factors and agents involved in any one patient, as is the case with many diseases, now it is often possible to describe much of the etiology and pathology of ITP quite accurately. Purpura refers to the splotches seen on the skin where capillaries have leaked blood to yield a bruise or many red or purple petechia (flat, pin-head sized spots). However, with careful monitoring of the platelet counts and appropriate treatment when the platelets approach a low level, people with this disease may rarely show any such symptom. Nonetheless the moniker ITP has stuck in the medical literature and will, as a result, continue to be used here.
The deficiency of platelets has two basic origins: autoimmune attack against platelets (primary ITP) and bone marrow disorder (usually: secondary ITP). In primary ITP, the bone marrow produces platelets as fast as usual (at least in the early stages of the disease), but even before they have a chance to mature, they are taken out of circulation. An antibody of the G series (the type involved in several autoimmune diseases), IgG, attaches to the platelets and marks them to be removed from circulation. It is likely that individuals who suffer this disease have a genetic propensity to get it, and that a viral disease triggers it. Many autoimmune disorders have this characteristic. In such cases, treatment is often aimed at inhibiting the immune system with corticosteroids (e.g., prednisone). If necessary, the spleen is removed (splenectomy) in order to both reduce the production of anti-platelet antibodies and to slow the clearance of the platelets from the system (the spleen filters out the platelet-immune complex). A suitable name for this disease is autoimmune thrombocytopenia.
Autoimmune thrombocytopenia occurs mostly in children and young adults (typically before age 30), though it can rarely occur later in life. Many times, it manifests as an acute disease, lasting a few weeks and then clearing up completely. It might recur again later after another viral infection or with reactivation of a chronic virus, but eventually it ceases to be a problem in the majority of children who experience it. The acute manifestation can usually be controlled by a course of therapy using steroids to inhibit the immune response for a period of several weeks. Chronic autoimmune thrombocytopenia develops in a small percentage of patients. In that case, steroid therapy eventually fails (due to the side effects from prolonged administration). Until recently, the main therapy for chronic autoimmune thrombocytopenia has been splenectomy, which is sometimes curative, but at least reduces the disease severity. More recently, intravenous (IV) infusion of normal IgG (hence the treatment initials: IVIG) to replace the body’s anti-platelet IgG has been tried with some success and may replace splenectomy for some patients. IVIG has also been proposed as an alternative to the initial therapy with prednisone. Other therapies are also being developed. Medical opinion appears to be leaning towards finding an alternative to splenectomy. read more