I feel that you need to understand first of all what is availible here in Thailand. For you guys coming here as tourists/short-timers like you, you need really to check things up, just like you do now.....
Healthcare for me is based on the public hospitals here i.e. Chaiyaphum. Their prices are many
hundred percent cheaper than the expensive private ones that you seems to be in love with. I paid as an example for removal of my gallbladder, including 3 days after-care at the hosital... totally 33.000 baht... BKK hospital in Khorat as well as St Mary´s in Khorat offered me 100.000 baht PLUS aftercare 3 days on top of that...... (30-40.000B)
And when it comes to bloodtests, it is really NOT a good idea to use BKK hospital for bloodtests.... Why not do like I do, google up private labs, they are all over the place and go there, they are really cheap in comparizon.....
good luck....