Legit anavar shouldn't have an effect on the thyroid.
I'm wondering if it's the opposite due to extensive research done on Oxandrolone/Anavar's effect on thyroid (TBG).
"Anavar is a unique anabolic steroid in relation to fat loss, due to it having a stimulative effect on Triiodothyronine (T3) levels (1). T3 is the active thyroid hormone that significantly increases lipolysis (fat loss).
Anavar increases T3 by inhibiting TBG (thyroid-binding globulin) and elevating TBP (thyroxine-binding prealbumin). This process effectively increases the conversion of T4 to T3. This is good news for bodybuilders, as T4 (Thyroxine) is the inactive thyroid hormone, and T3 is the hormone that stimulates fat loss."