hi. in Ontario, we have Gamma-Dynacare, CML, Alpha Labs, etc. I am not sure which blood labs you have there, but you can call their head offices and find out if they do certain tests. You may have to be persistent because they will likely ask you to tell your doctor to call them instead. You may be able to access the test menus online also.
Also, hospital labs often do specialized tests. You can call the blood lab of a hospital and ask to speak to someone there about their test menu. They will probably also ask your doctor to call but sometimes, you get lucky.
You can also send blood to some of the American labs if your doctor is willing to help; I have been doing this for many years. It would help if your doctor is willing to open an account with the lab, which is sometimes necessary. This is free, but many doctors refuse (not sure why).
xoxo