Can you tell me how i could tell my parent that i have dysthymia?

Talk to them: Tell them how you have been feeling and that you think you need some help. Let them know that you need their support and do not blame them for the depression. I am assuming that you are a minor and not in your 40's you can also speak to a school guidance counselor or psychologist. They will help you speak to your parent. Let me know if you have additional questions.

Just be candid: Tell your parents about your mood, energy level, concentration, memory, self esteem, motivation levels, sex drive, sleep & appetite. Crying spells, feelings of helplessness or hopelessness are pertinent as well as your capacity to feel joy. Let them know immediately if you have suicidal thoughts.

Boundaries: Ask yourself, what benefit does it serve to tell your parents? Do they need to know? How will they react? You certainly do have a right to privacy, and just because they are your parents doesn't mean they automatically need to know everything that's going on.