I Have Hypothyroidism And Have A Yearly Blood Test To

I have hypothyroidism and have a yearly blood test to check my levels. This July with my blood test my Dr noticed a higher level in my liver enzyme....I repeated the test the first of August and the level dropped..I will have another test in Sept. What causes the liver enzymes to increase? What do I need to be checking myself in the supplements I take for ingredients that can cause the liver to produce higher enzymes? I am a very healthy 62 yr old woman