If depression and anxiety are a neurochemical imbalance, how can doctors measure or examine that?

There's no test for neurotransmitter balance or anything like that is there? How do they know the neurotransmiiters are off? Any medical expert advice?

There is no direct test of neurotransmitters as the cause. There is inference from animal studies (lab research that includes dissecting brains). There also is the efficacy of antidepressants which are known to block reuptake of neurotransmitters. As for biochochemical cause/effect, there are studies of human cadavers which show smaller hippocampal volume, some loss of grey matter, and other brain changes. Additionially, there are spect scans which still are a bit controversial. These latter studies don't get to specifics of neurotransmitter involvement. In fact, there is a line of thinking that the neurotransmitters are the start of a chain of reactions and not the cause itself. (This actually makes a lot of sense, IMO, but I'm not an expert.) They do, however, confirm physiological changes in the brain from chronic major depression (not short lived situational depression). So..... diagnoses are based on a process of elimination (other medical causes), behavior, self-report, and reporting by others.

99% of the ime, it's a psychiatrist's knowlege and experience that make a diagnosis. That's why it's important to be totally honest. They have found that the neurotrnsmitters in the brain fail to pass enough (seratonin, dopamine, etc) across the synapses, but they can't x-ray your head to see what you're suffering from. The meds can supress the chemical transfers and help you feel better.

Believe me, these doctors are looking at more than what you tell them when they talk to you. They read your body language, tics, hand movements, panic in the eyes, sadness, etc. If you're a typical case (and hope you are, I'm not) they can diagnose with a high degree of certainty. Lack of seratonin causes depression; lack of vitamin C causes rickets. It's the same principle.

They are neurochemical imbalances, and doctors (neurologists) can measure it by doing tests and brain examinations.
However in most cases they won't - they'll use experiance to determine what is wrong with you by your behaviour and putting two and two together.
This is less accurate which is why it can be difficult to know what exactly will help a patient and why sometimes they are no help at all.

There is no blood test for mental illness.

Nobody knows the cause of mental illness.

There is no cure .

You will have it all your life.

The drugs are a nightmare to take.

The doctors can not even cure shyness.

Most doctors have a mental illness that

they are looking for a cure.

There is a lot more art in mental health then science. They are only taking their best guess and don't know.