Treatment of a premenopausal woman with an isolated TSH >2.5 mIU/L

Does an isolated measurement of a thyroid-stimulating hormone (TSH) level >2.5 mIU/L in a premenopausal woman warrant treatment? Should the measurement be repeated or supplemented by other tests?

René Rodríguez-Gutiérrez: This is also a very good question, because there is a lot of controversy about the normal upper limit cutoff for TSH. There are some that advocate 2.5 mIU/L instead of 4 or 5 mIU/L that we have been used to. The reality is that we do not have good data to show that treating patients below 2.5 or between 2.5 and 4 or 4.5 mIU/L makes a difference. I will say that for now we cannot say with confidence that we should treat premenopausal women to below 2.5 mIU/L.

Personally, I believe there are 2 sets of particular populations that may benefit from this. These are people that are fighting with infertility, and the other [group] would be those that have mood disorders such as depression. Also, the evidence for that is not very robust, but I will say that maybe in those populations we have more consistency in the evidence of benefit.