Yes, unfortunately this is true. You will get pay cut in *ALL* cases unless you check-in first at the airport and then report sick.
The recent memo from the chief pilot was merely asking pilots to give heads-up to the crew dispatch so that they have time to find a replacement for you without delaying a flight.
This, however does not relieve you from the requirement to check-in and then go to the company doctor.
This is certainly not nice and hopefully will change one day
By the way, for TK pilots there's a closed forum at
aerocrew.net
You need to either register with your THY e-mail (that you can change later on) or provide any other proof you work for Turkish in order to join TK Flight Crew group
Regards!