Hundreds of different ones. Granted you still need some level of medical expertise to be able to accurately interpret results on a lot of them but a smart enough layman could probably self diagnose some illnesses with enough homework.
We even need a prescription for repeat labs. So if my doctor is away for personal reasons for a month and I need to have my [thing that I get tested every month] checked, I can't without having to navigate the entire healthcare system to find a workaround.
I would be easy for me to interpret the results as my doctor is clear that [number] should not fall under [threshold]. It even comes back highlighted in red on the result sheet if it falls under that number. And I have clear instruction on what to do if that happens.
Hundreds of different ones. Granted you still need some level of medical expertise to be able to accurately interpret results on a lot of them but a smart enough layman could probably self diagnose some illnesses with enough homework.