What's wrong with me???

  I am a 21 year female who only seems to have seizure when I am sleeping.
  I also always have them when I am on my period.  I was at a "not so good"
  hospital this last weekend, and I had had four seizures and they did a
  tegretol level (I am on 400mg XR in the morning and 500mg XR at night) and
  they said that it was zero.  I don't understand how it could be zero if I
  was taking my medication, which I was.  Then a few days later I had another
  one and I got a new level taken at a different location, and they said my level
  was 8.9.  I don't understand what is going on and I don't get to see my
  doctor until Jan. 7th.  My questions are:  What is the normal range on the
  tegretol XR levels?, Does my period have something to do with this?, and What
  could have caused my tegretol level to read zero?  I have only had seizures
  since I was 16 and there is no known cause.  I have had CT scan, MRI, and
  multiple sleeping tests.  No results were not normal.  Please help!

[CCF Neuro MD MJD]

The normal range of Carbamazepine levels depends on the laboratory but generally ranges from 6-12 ug/ml.  Keep in mind, however, that this is a rough guide for physicians.   Some people could have adequate control of their seizures at a level of 7 ug/ml. Others may still be seizing frequently at levels of 13 ug/ml.  Control is different for different people.  The same is true for side effects. So neurologists generally titrate medication doses upward until seizure control is reached or side effects occur.  It does seem strange that your level was zero and then a few days letter was therapeutic.  Even people taking suboptimal doses of medications will have low levels but not zero.  Remeber although your docot's appointment is in January, you can always call his office asking a question about your levels.
As for your period, many people report increase in their seizure frequency  around their menses (so called, "catamenial epilepsy").  Sometimes, it gets so severe that people have to take a benzodiazepine at this time along with their usual medications to try to prevent seizures.
Sometimes, epilepsy occurs without a known cause, but keep plugging away at a diagnosis, perhaps even coming to an Epilepsy Center at a large medical center.  Diagnostic imaging of the head an epilepsy monitoring has advancced a great deal, and may be able to characterize your epilepsy further.