Hi,
Thanks for writing in.

Serotonin is a brain chemical secreted by nerve cells normally.
Serotonin levels are usually tested clinically only in case of tumors secreting serotonin. So the test is usually done to detect high levels in the blood. Different laboratories have their normal values that may vary slightly.

There is usually a high cut off above which the diagnosis of the abnormal level is done. It is not mentioned any where clearly but unmeasurable probably does indicate a low value.

Serotonin levels are rarely tested for depression outside a research background.

I would be glad if you could tell me about the exact nature of symptoms. Do the tremors and/ or memory loss occur continuously or episodic along with episodes of confusion.

Another important information I would like to have is if the serotonin levels test was done while you were taking Lexapro? if yes then for how long were you on Lexapro at the time of getting the test done?

Also important would be to know any investigations, CT scan brain, EEG done on you and if your depression has improved after taking Lexapro.

Further questions welcome.

Regards
Dr Vivek

---

Hi,

Thanks for writing in again.

From the history you have provided, of intermittent tremors or abnormal movements of the body with loss of memory and confusion may be a complex partial seizure. You also report that it has reduced mildly with primidone (which is an anticonvulsant). Seizure phenomena can be seen in varied forms depending on the involvement of specific parts of the brain. It is suspected especially when there are abnormal movements in specific muscle groups in the body because every muscle group has a specific representation in the brain, the involvement/irritation by a seizure focus of the part causes abnormal movements there. One of the hallmarks of seizures is amnesia or loss of memory for that episode followed by confusion (confusion may or may not be seen in all cases or all episodes). There is also a partial component that precedes this which most commonly involves abnormal movements of parts of the body (in this phase the patient is aware of the symptoms). Another feature of a seizure is the striking similarity between every episode.

The other possibility is that of a panic attack. Here there can be episodic symptoms which may involve any of the following – tremors (usually whole body tremors or involving limbs), palpitations, sweating, confusion, a feeling of impending doom as if one is about to die or have a heart attack and very rarely memory loss may occur owing to the anxiety the patient goes through.

A good EEG is quite sensitive to record any abnormal activities in the brain in order to diagnose a seizure. Higher the number of leads in the EEG machine, better the sensitivity of the recording. If the episode occurred during the recording, it would be easy to distinguish it from any other phenomenon. Otherwise it would be as good as any other inter-ictal recording done for few minutes. But a negative recording does not rule out the possibility of a seizure phenomenon.

None of these conditions would yield any findings in CT/MRI brain unless there is a lesion leading to the symptoms. In these cases the neurologist/psychiatrist will use his clinical judgment regarding treatment with anticonvulsants and whether the dose of lamotrigine needs to be optimized or an additional drug needs to be added.

A well known neurochemical cause of depression is low serotonin in the brain. Antidepressant drugs like escitalopram are given to increase the serotonin level. Sometimes, due to various reasons, these drugs may increase the serotonin level to such an extent that may lead to serotonin syndrome. But since the serotonin was not high it was ruled out. So a low or unmeasurable level of serotonin is not something unexpected in your case.

I hope this answers your question,
Wishing you good health.

Regards
Dr Vivek

---