Psychiatrists: how can we determine whether a particular person produces enough seratonin to keep said person in good health? Is there a blood test?
I am not a psychiatrist, but a retired mental health nurse with some knowledge of the subject.
Levels of free or attached Serotonin in the blood stream would indicate nothing in particular; the important fact is the true availability at the synapse.
Blood tests can be used to check whether the Serotonin is at therapeutically effective levels in the blood during treatment, but IIRC this is a crude measurement- mostly it tells you if they are taking it or not; I don’t know of any generally accepted levels for therapeutic effectiveness.
Hope that helps.
Serotonin is used both as a neurotransmitter, by the brain, and as a vasoconstrictor, in the circulatory system. Circulating serotonin does not cross the blood brain barrier, so the serum level has very little to do with the amount found in nervous tissue.