I had my general practioner write up a blood test for me with the elisa test. I took it, and it came back low positive. I registered a .53, and was told that any reading above a .35 is considered positive. It was listed as a level one, which is the lowest, but I still have candida issues.
So yes, you can get a blood test and yes, it can show your level of candida. But a word of caution, I just spoke with a naturopath that said that you can have candida and it may not show up on a blood test.
My advice would be to get the elisa blood test (I've also heard the mona blood test is a good one) and see what that says. Then, see a naturopath and get his/her opinion.