I am on 50mcg of levoxythyrine and my tsh level went from 1.28 to 3.40 in 4 months. what would cause this change ? it is usually around 1.2-1.4.

TSHLevel: Tsh levels vary considerably from hours to hour over the 24 hour day period. Highest at 8-9 am and decease after. Other variables are involved , using antibiotics, straying oral contraceptive , timing in relation to food and vitamins.

Generic: Often switching from generic to brand, TSH can pop up. Get doctor to increase synthroid (thyroxine) if repeat TSH is higher.