Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the symptoms of Thrombocytopenia ?
    ### Response:
    Mild to serious bleeding causes the main signs and symptoms of thrombocytopenia. Bleeding can occur inside your body (internal bleeding) or underneath your skin or from the surface of your skin (external bleeding).
                
Signs and symptoms can appear suddenly or over time.
    