Chronic Primary autoimmune platelet disorders
Causes and risk factors
The estimated incidence in adults is between 1.6 and 3.9 per 100,000 population per year. The average age of the population with ITP is quite advanced (56 years) with a marked tendency for the prevalence to increase after 60 years of age, while in the younger age group there is a ratio of 1.7 in favor of females, the female-to-male ratio is 1.3:1. Although ITP can occur at any age, the incidence shows a bimodal age-specific distribution in men, with two peaks in incidence: in boys under 18 and in elderly people.
Which are the symptoms?
In autoimmune thrombocytopenia, hemorrhagic manifestations are the most recognizable symptoms with a prevalence of petechiae and ecchymoses (bruises) on the skin, together with bleeding from the nose (epistaxis) or from the gums (gingivorragia). Other frequent symptoms are hemorrhagic blisters in correspondence of the mucous membranes, bleeding of the gastro-intestinal and genito-urinary system (presence of blood in the urine) and, in women, more abundant bleeding during the menstrual cycle. Spontaneous hemorrhagic symptoms generally occur at platelet levels lower than 20-30 x 109/l, while in case of minor traumas or in subjects with concomitant coagulation defects they can occur even with higher platelet levels (> 50-60 x 109/l). Some patients are almost asymptomatic, even in the presence of reduced platelet levels, and the detection of the disease is completely accidental during routine examinations (CBC).
How is it diagnosed?
The diagnosis remains essentially clinical and is based on morphological examination of the peripheral blood, the objective examination of the patient, the collection of anamnestic information to exclude other possible causes of thrombocytopenia, especially those of infectious type or exposure to drugs or toxic substances. However, particularly in children unresponsive to corticosteroids or with chronic ITP and in adults unresponsive to intravenous infusion of immunoglobulins, a bone marrow evaluation is recommended to exclude the presence of primary malignant hemopathies. In the absence of clinical or laboratory parameters for defining the duration of the disease, "newly diagnosed ITP" is defined as all those cases that are present at the first time to observation. On the other hand, "persistent ITP" are those forms that in the interval between 3 and 12 months after diagnosis do not obtain a spontaneous remission or do not maintain a response to therapy when this is suspended. The term "chronic ITP" is reserved for those patients in whom ITP persists for a period longer than 12 months.
How is it treated?
All guidelines, both traditional and more recent, agree that the purpose of treatment is to prevent bleeding. A platelet level higher than 20-30 x 109/l is considered an acceptable safety limit for a subject who does not carry out particularly risky activities or does not suffer from concomitant congenital or acquired (antithrombotic therapies) coagulation disorders. American Society of Hematology (ASH) guidelines suggest initiating treatment in newly diagnosed adult patients with platelet counts less than 30 x 109/l. First-line treatment involves the use of corticosteroids (prednisone, dexamethasone). The use of high-dose intravenous immunoglobulins is indicated to patients with muco-cutaneous hemorrhagic diathesis. In cases that do not respond to first-line therapies or that relapse after an initial response, second-line therapy is proposed with splenectomy (elective surgical removal of the spleen), the use of monoclonal antibodies (Rituximab), immunosuppressive drugs and thrombopoietin receptor agonists (TPO-ra).