Blood Drug Testing

Why don't Psych Doctors run blood tests before prescribing meds?

I understand that having blood level ran on Serotonin, Norepinephrine, Dopamine etc., would not diagnose the actually problem. Still, wouldn't it give them a better idea of where the patients levels were to begin with? For instance, there are some people that would have an abnormally high level of serotonin. People with Chronic Fatigue Syndrome frequently have higher levels than normal, yet they are frequently given SSRI's. You certainly wouldn't want to give them anything that would increase this level. But besides all that.....That's what Psychiatrists are dealing with. Brain chemistry. Why wouldn't it be standard practice just to run these tests, just like any other doctor would have labs done for any other illness? It makes ZERO sense to me!!!!!!! First of all, I am assuming nothing. If you read the question, I am simply asking why it wouldn't be common practice, just like any other doctor would run labs..very simple. Secondly, if you read the question, I stated that I am aware that a blood test would not show what the problem was. But it would give the doctor an idea of what the persons levels were to begin, which may in fact indicate another issue that should be addresses. So I guess what a few of you are saying is that the entire process is subjective. "Attempt" to treat the symptoms, not possibley cure the problem. There is absolutley NO objectivity with some of your responses. Trial and mostly error is the goal. This is exactly why so many people have issues with psychology. The errogance level to sit in front of someone who is desperately seeking medical attention, is very impressive. Don't get me wrong, I'm all for therapy. I just don't understand why there is very little "medical" testing involved.

Public Comments

1. Asking about drugs or anawering about them will get you suspended
2. Because the amount of these substances in the blood has absolutely no bearing on their behavior in the brain. Outside the brain for instance, dopamine is involved in the regulation of blood pressure and certain other body processes, norepinephrine and epinephrine are the primary neurotransmitters involved in controlling heart rate, blood pressure, smooth muscle tone and an enormous number of other sympathetic nervous systems. Serotonin is involved in regulation of certain digestive processes in the GI tract. There's something called the blood-brain barrier that isolates the chemistry going on in the central nervous system from the rest of the body. For the most part, substances inside the CNS cannot exit, and substances outside cannot enter - unless specifically transported across it. The only way to determine the amount in the brain would be to go in and take a chunk of it out to examine - obviously not something you want to do unless you've got no other option. That said, there -are- developments in certain kinds of imaging, based off of SPECT (a technology related to CT scans) and functional MRI that are able to measure the metabolic behavior of neurons in the brain, and to do so non-intrusively. However, these are still in research stages, fabulously expensive, and many years away from clinical use. EDIT: There is little laboratory testing, because there are few to no useful laboratory tests in existence. That simple enough?
3. Because they might discover another problem.
4. Why would they do that? Neurotransmitters DO NOT show up in blood, they are only in the central nervous system. As such, they can not be measured.
5. Psychiatrists do order blood tests on occasion. They just aren't often useful. And why would you assume that disordered chemistry at some site in the brain has anything at all to do with blood or serum levels? That's a huge, huge difference.