Can wait gain or loss impact thyroid levels on blood test? i have never had an abnormal thyroid reading until now, but i also have lost almost 40 pounds. does that make a difference? waiting to see usual doctor in a week?

It is the opposite of your question. Thyroid problem can make you lose or gain weight but not the other around, i.e. weight gain or weight loss does not change thyroid hormone levels.

Agree with Dr. Le. It would have helped had you provided the before and after lab results to ascertain in the difference is clinically meaningful. Your doctor is in the best position to interpret your lab results as s/he knows more about your health! Wish you good health!