Page 1
Typical examples are given for each mechanism. In ITP and DITP two mechanisms are involved. Abbreviations: DIC, disseminated intravascular coagulation; DITP, drug-induced immune thrombocytopenia; HIT, heparin-induced thrombocytopenia; ITP, immune thrombocytopenia; MDS, myelodysplastic syndrome; TTP, thrombotic thrombocytopenia purpura. Multiple mechanisms (increased destruction and decreased production) are involved in ITP, drug-induced thrombocytopenia and hepatitis C virus (HCV) and human immunodeficiency virus (HIV)-induced thrombocytopenia. When evaluating a patient with thrombocytopenia, it is important to exclude pseudothrombocytopenia, a falsely low platelet count, caused by in vitro agglutination of platelets occurring in approximately 2% of patients with thrombocytopenia, when the blood is collected in ethylene diamine tetra-acetic acid (EDTA) containing tubes. If true thrombocytopenia exists, stepwise evaluation is needed. In clinical practice, physicians are frequently faced by a patient presenting with a new onset severe thrombocytopenia, the cause of which is occult. The most challenging issue is to find the cause in the shortest time and to treat the patient accordingly. Ideally, the adequate treatment should be given in respect to etiology, but in the real world, especially if a patient presents with bleeding, it is not possible to gather all the necessary information that would allow the clinician to weigh all the pros and cons of different treatments, since treatment should be given immediately. In those cases, treatment that has a rapid onset of effect and is minimally harmful is reasonable. Thus, the treatments given in emergency situations, for example platelet transfusion, usually are not long-term therapeutic options. On the other hand, platelet transfusions may not be helpful in certain etiologies, for example in ITP, heparin-induced thrombocytopenia and thrombotic thrombocytopenic purpura (TTP). Therefore, it is very important to recognize the signs and symptoms of these entities. In this review we attempt to provide an algorithm through which the cause(s) of thrombocytopenia can be assessed.
Approach to the patient with thrombocytopenia Family history, medical history and concomitant medications A detailed history can provide important information regarding the etiology of thrombocytopenia and facilitate diagnosis. The most important aspects that should be investigated include the following: the presence of a family history of thrombocytopenia (it is surprisingly common to diagnose congenital thrombocytopenia not only in children but even in adults ); disease history, paying special attention to recent viral and bacterial infections; vaccinations [6]; malignancies; possibility of pregnancy; recent travels (e.g. exposure to malaria, rickettsiosis, dengue fever); recent transfusions; ingestion of alcohol; dietary habits; and risk factors for HIV and viral hepatitis. Particular points of interest are medications taken by the patients, especially those started 1-2 weeks prior to the development of thrombocytopenia.