Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Thrombocythemia and Thrombocytosis ?
    ### Response:
    Primary Thrombocythemia
                
In this condition, faulty stem cells in the bone marrow make too many platelets. What causes this to happen usually isn't known. When this process occurs without other blood cell disorders, it's called essential thrombocythemia.
    