Which of the following is a symptom of thrombocytopenia?

Thrombocytopenia refers to a low platelet count in the blood, which can lead to various symptoms related to bleeding and bruising. Headaches are a symptom often associated with thrombocytopenia, primarily due to the potential for bleeding in the brain if the condition is severe enough. Patients may experience recurring or severe headaches as a result of spontaneous bleeding or increased intracranial pressure.

While the other options listed can be related to different medical conditions, they are not typically symptoms of thrombocytopenia. Chest pain may stem from cardiovascular issues, polyuria relates more to diabetes or renal issues, and shortness of breath is often associated with respiratory or cardiac conditions. Thus, headaches stand out as more directly connected to the implications of thrombocytopenia and its potential complications.