I wonder how many people have been asked to pay for extra tests when getting their partner medical in Bangkok.Particularly thyroid tests

Why do you ask ?

Generally extra tests are not asked for unless clarification is needed or unless there is something that has raised a concern for Immigration

I asked because I was asked for 13,000Baht for tests, I took wife to another DR who laughed and said no problem. after he did biopsy (?) for 1200Baht

I asked because I was asked for 13,000Baht for tests, I took wife to another DR who laughed and said no problem. after he did biopsy (?) for 1200Baht

A biopsy is not part of the normal tests, I take it that something came up in the original tests.

AFAIK, all tests including additionally requested tests must be done at one of the nominated hospitals, If you get it done outside of that then it may not be accepted.

Unfortunately you are feeding us only snippets at a time....pretty hard to give an answer without all the details.