I am sort of confused.

- my thyroid was functioning normally before Lithium
- eventually, on Lithium, I developed underactive thyroid
- I was put on synthetic thyroid hormone and was OK for a while
- then I became very sick and was taken to urgent care by a coworker. "Nothing nothing nothing wrong with you!" - sent home with no answer
- then they called me back late at night as they got the last test result in and knew the answer - severely under active thyroid
- my synthetic thyroid hormone dose was increased. I worked from home for a week or two before extra synthetic hormone kicked in because I literally had no physical strength to move my body. Sat at the computer though.
- in Feb of this year I went off Lithium and off the synthetic thyroid hormone, assuming that I did not need it while OFF Lithium
- I do not eat much (small appetite) but keep putting on weight, so Confused suggested a thyroid check, and, SURPRISE,
- I still have under active thyroid and need to be back on the synthetic hormone (at first, a low dose for two months and then re-check and follow-up).

Free T4 is normal.
TSH is High (==> low level of the thyroid hormone)
TSH 5.37 Normal range=(0.34 - 4.82) uIU/mL H

The endocrinologist does not know if Lithium can cause damage that lasts beyond the time Lithium is taken.

Has anybody had that experience?