elevated liver enzymes

Hi, not being familiar with how this works, I submitted the following issue in the  liver disorder community.  I just thought it might be a good idea to post it here too.

About three months ago, during a routine blood test, my liver enzymes were elevated in the 700 and 800 range.  I went to a specialist, and he ordered tests, blood tests, and a sonogram, and a fecal test.  All of my tests came back normal, and all types of hepatitis were ruled out.  After subsequent blood tests, my enzyme count went down to just under 300, but in the latest test, they were back up to 500.  I had been taking milk thistle,  and a detox product, which I stopped, and I didn't take the milk thistle as conscientiously as I had previously done, but am still taking it. (Could some of the other supplements I take be causing a problem.  I checked and found that all of the ingredients are supposed to be helpful to the liver.)

I would also like to add, that a year ago, my enzyme count was in the two hundreds, I researched and found that co-enzyme Q10 might cause such a reaction, and when I stopped taking it, and began milk thistle, and a detox, my count went to normal.

I would like to know what else could be wrong, since all my tests came back normal, I have absolutely no symptoms at all, I am very healthy 72 year old female, 130 cholesterol, 120/60 BP, and slightly overweight, and exercise 3 or four times a week. I take the lowest dose of Estraderm twice a week for several years,   and 112MCG Synthroid daily.  I am very puzzled about this, and what can I expect my doctor to do next.  

Any input will be greatly appreciated.
Thank you very much.