With the widespread use of automated cell counters, clinicians in any field of medicine may encounter thrombocytopenia. The symptomatology may vary greatly and the underlying cause may be either inconsequential (pseudothrombocytopenia) or life threatening. It is important to be aware of common conditions leading to thrombocytopenia and have a systematic approach to evaluation and management of these patients. In this review we highlight common etiologies seen in adult patients with thrombocytopenia. A brief description and management approach to common conditions, as well as to conditions that may be less frequent but require emergent intervention, is provided. Often the clinician is called upon to make a decision about platelet transfusions. The review also discusses the various types of platelet products available for transfusion and gives guidance regarding selection of the appropriate product, indications and contraindications, and suggested target platelet counts for various clinical situations.
* Thrombocytopenia may confront any physician who orders blood counts, in any field of medicine.
* An evaluation algorithm and a listing of common causes will help clinicians diagnose thrombocytopenia and be able to triage life-threatening from less serious causes.
* In vitro platelet clumping (pseudothrombocytopenia) is common and must be differentiated from true thrombocytopenia.
* Physicians should be alert to the possibility of heparin-induced thrombocytopenia, as a delay in diagnosis can result in serious morbidity or mortality.
* A summary of indications and suggested thresholds for platelet transfusions in various clinical situations is included.
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