I had a lobectomy and diagnosed with Hurthle Cell Carcinoma in 2022. I had a very large nodule, but never had any “thyroid issues” prior to this surgury. A short while after surgery, it was determined that I needed to go on medicine and I am still having a VERY difficult time getting regulated on the medications. Medication changes and dosage changes caused side effects that increased and decreased but were still hard to manage. I have not been able to get regulated….yet. (The side effects can be quite bad!)
Due to this situation, I have done a lot of research and spoken to pharmacists about medications. A pharmacist told me that the pharmaceutical company does not have to tell you if they change their product as long as they do not change the main ingredient…..they can change the fillers without any notification. She also told me that when a company changes their active ingredients they notify pharmacists however it is usually just a change in the leaflet that most patients don’t read.
A few months ago, Synthroid and another medication had a recall due to an error in the strength of their medication. I was told that if a persons medication was part of the recall, they would be contacted, however I never heard about the recall until I saw it on the news. If you get several months supply of your medication, maybe you should check on the recall.

Another possible issue could be where the medication for your prescription was from. My nephew takes medication for ADHD and after refilling his prescription he developed a very bad allergic reaction (I don’t recall what it was). When my sister called the doctor, they told her to check with the pharmacy to see if the distributor was the same from her previous prescriptions and they found out that it was different. The pharmacy gave him the same prescription with pills that came from the distributor that they had previously used and he was fine. My sister said that the pharmacy has his prescriptions flagged so that they only come from one specific distributor.

Although the issues “could” be something internal, it might be worth exploring the medication just in case it is causing changes in your blood tests.
Good Luck!