Insurance requests TSH

I have hypothyroid. Very mild case of it but he medicated me anyway due to my weight. MY insurance requested a TSH today. Exactly how does this have anything to do with surgery. Does anyone know? As a nurse I do understand what TSH is but hypothyroid only contributes to obesity it does not make you super morbidly obese. Anyway I was curious if anyone knows about this or why they would request a TSH?

Only thing I can think of is maybe they think I have not kept up with my levels and kept my meds where they need to be and might deny if I am above the range.