Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes What I need to know about Erectile Dysfunction ?
    ### Response:
    To find the cause of your ED, your doctor may
                
- take your medical and sexual history  - ask you questions about your mental health  - give you a physical exam  - test your blood  - give you a nighttime erection test  - perform an injection test  - perform a Doppler penile ultrasound

    