On their website https://chulalongkornhospital.go.th/kcmh/en/dept/checkup-center/ it states
1. Individual health checkup.
Pre- appointment 2 days in advance ( Not including Saturday and Sunday) via Email : checkup.chula-email removed
For more information, please call 02 256 4863 ,02 256 4843
I sent an email to the email address on this website but after i sent the email i get email back saying the following
Address not found
Your message wasn't delivered to checkup.chula-email removed because the address couldn't be found, or is unable to receive mail. Looks like the email address they have on their website is incorrect
Tried to call the phone number they provided before 3pm a few times but no answer on the phone.