Thyroid Stimulating Hormone Stability in Patients Prescribed Synthetic or Desiccated Thyroid Products: A Retrospective Study.

The purpose of this retrospective matched-cohort study was to evaluate the stability of thyroid stimulating hormone (TSH) in patients using synthetic compared with desiccated thyroid products. Patients using a thyroid product for the treatment of hypothyroidism were matched 1:1 on age, sex, race/ethnicity, and had a follow-up period of 3 years after the index date. The primary outcome was percent of in-range TSH values. Over 3 years, TSH values in both groups were in-range 79% of the time ( = 0.905). Our results showed no difference in longitudinal TSH stability between desiccated thyroid products and synthetic levothyroxine.