@tinaesims Hi Tina. If you are on Rifampin or Rifabutin -- as part of your NTM treatment -- your thyroid counts can go low, sometimes very low. This does happen to some people. Some other people don't have much problem.
Rifampin particularly interferes with Levothyroxine meds, reducing their effectivesness, so you can become low thyroid. (Technical info: Rifampin can be a moderately strong to strong CYP3A4 Inducer in interactions with Levothyroxine, and with Rosuvastati,n etc. Doctor could check Drugbank.com for more information about these interactions).
This certainly happened to me. Rifampin reduced the effectiveness of the Levothyroxine I take, so I ended up with low thyroid T4 and high TSH. It also flattened the Statins I was taking, so I ended up with high cholesterol (high lipids) all of the time.
In the end the Pulmonologist took me off Rifampin and replaced it with Clofazimine instead.
All the best, Annie