I'm sorry to say that there is no scientific basis for this sort of testing. There is no useful information to be obtained in saliva, urine (or blood, for that matter), with respect to neurotransmitter status. If there was, surely your regular doctor would start there.

I'll give you an example. In urine, the tryptophan/serotonin metabolite indoleacetic acid is often used as a marker for what they are calling the "serotonin level" in the body. The fact is, there are a number of different pathways from tryptophan to indoleacetic acid, some of which bypass serotonin altogether. Moreover, less than 10% of the body's total serotonin content is in the brain. There is no way to know whether indoleacetic acid in the urine arose in the brain, or from serotonin breakdown. Studies which sought to correlate urinary indoleacetic acid content with cerebro-spinal fluid (the plasma-like substance that washes the brain and spinal canal) found no correlation whatsoever. Moreover, mood status was not correlated with either measure.

In the end, this sort of testing is useful only in transferring your money to the bank accounts of the laboratory and/or the practitioner ordering the tests.

Far better to consider your own symptoms, and do trials of nutrients which might enhance your own body's ability to generate neurotransmitters. In the end, that's all the tests would accomplish. You'd still end up at the same decision point. You don't need tests to know what your symptoms are.

Lar