I´m going to Adana at the end of October.From Helsinki, through Istanbul to Adana. I need to know. Do i have to take care of my suitcase in Istanbul airport. Or will they be transferred by the Airport people to Adana plane If anyone can understand what i just tried to say.

No worries, problem yok. Have done the same thing before
If you fly with THY from Helsinki to Istanbul and from there to Adana - you don`t have to worry about the luggage. You will get in Adana.

Good luck. There`s nothing to worry about. Although i was very nervous the first time myself. But it went perfectly well.

Thanks for the answer Maria/mesut
I´m sure i will be nervous too. But i know everything will be just fine

If Adana has a customs office because it is an international airport, you don't have to worry, THY will transfer your luggage. But if Adana has only domestic flights you have to pick up your luggage on the international lounge of Ataturk Airport, check it in again (it's a piece of cake) at the domestic part of the airport. That was the procedure THY told me when I flew this year from Amsterdam via Ankara to Elazığ. THY is not allowed to handle your luggage if there is no customs at your final destination.

Trudy, that sounds strange. I have gone to different domestic airports and last time i went to Diyarbakir, which definately is only a domestic airport

I always get my luggage at my final destination and have been given the option wether i want it in Istanbul or not while changing plane...

Just take care. If you are NOT flying THY - you MUST go through customs with your luggage and clear everything at Istanbul. I fly Emirates and the first occasion came close to loosing my luggage following someones advice that was incorrect. Its ONLY THY that offer this service.