Adrenaline, Noradrenaline, Dopamine, Serotonine, Cortisol, GABA and many more...
Just google "lab test" for these.
The results all talk about tests that measure levels in the urine or blood, not the level in the brain, sorry if I'm being thick, but I don't see any actually measure brain levels.
Parent poster is responding to your question:
> What kind of things can they measure from urine and saliva?