Thyroid Issues (Cancer Risk, Nodules, Storm, etc.)
Users on Reddit discuss a range of topics concerning thyroid issues and GLP-1 medications, including cancer risks (particularly Medullary Thyroid Carcinoma), the development or discovery of nodules, and impacts on existing thyroid conditions like Hashimoto's and Graves' disease. There's also discussion around recent studies and the interpretation of warnings associated with these drugs.
Thyroid Cancer Risk & Concerns:
Studies and Interpretations: A post shared new medical information suggesting GLP-1s are not linked to thyroid cancer in a large study with a relatively short follow-up (1. 8 to 3. 0 years). [1] However, some users remain cautious. One user mentioned, "Jury is still out on if this occurs in people, but it was linked in rodents- have a patient with metastatic medullary thyroid cancer who had started a GLP-1 about six months earlier. Also could just be a bad coincidence, but 🤷♂️"[4] Another user cited a BMJ study concluding no substantially increased risk over a mean follow-up of 3. 9 years, but a commenter noted the comparison to DPP4 inhibitors wasn't entirely convincing. [10]
Anecdotal Cancer Mentions: One user anecdotally reported, "I’ve known several people on it. All ended up with cancer. Many ended up with pancreatic cancer, one with thyroid cancer... " but also stated, "I can’t prove these are the cause or if there were other circumstances that influenced these outcomes, but it seems too consistent to be entirely coincidence. "[9]
Doctor's Advice on Risk: A user with Hashimoto's was told by their doctor they weren't a good candidate for GLP-1s because "the side effects include thyroid tumors. "[16] However, another user with Hashimoto's was told by their endocrinologist that the risk isn't higher for Hashimoto's patients for MTC because it's not the more common papillary form that has seen an increase in rodent studies. [17]
Thyroid Nodules and Goiter:
Another user reported that GLP-1 use "led me to getting diagnosed with thyroid cancer. I lost enough weight that large lymph node was really noticeable. It did not cause my cancer because there was evidence of cancer years before. "[8]
Impact on Existing Thyroid Conditions (Graves', Hashimoto's, Hypothyroidism):
Hashimoto's Thyroiditis: A user with Hashimoto's taking Ozempic noted, "One side effect that happened to me was due to the Ozempic slowing my digestion, my body started absorbing my meds better, and I have had to repeatedly lower my synthriod dose over the past 2 years. My TSH levels bottomed out, and I began having symptoms of hyperthyroidism. "[18] Another user with Hashimoto's reported that microdosing semaglutide has been shown to reduce TPO antibodies. [12]
Hypothyroidism: A medical professional commented, "I do occasionally see my already hypothyroid patients actually need higher doses of levothyroxine on GLP-1 even with weight loss which I mostly to lowered absorption due to decreased gastric emptying time. "[3] Another user mentioned their thyroid meds would need adjustment after weight loss on GLP-1s as their "TSH went too low and I had to reduce T4 dose. "[11]
A user with Crohn's and Hashimoto's Thyroiditis experienced out-of-control nausea on tirzepatide. [15]
Thyroid Storm/Hyperthyroidism:
Remedies and Preventions Recommended:
Monitoring Thyroid Levels: For those with existing thyroid conditions, regular monitoring of thyroid levels (TSH, FT3, FT4) is advised, especially when starting or adjusting GLP-1 medication, as thyroid medication dosages may need to be changed. [5, 11, 18] One user with Graves' and Hashimoto's planned to have levels checked every few weeks. [5]
Consultation with Doctors: Users consistently recommend discussing concerns with endocrinologists or primary care physicians. [1, 5, 16, 18]
Awareness of Medication Interactions: Users highlight that GLP-1s can affect the absorption of other medications, including thyroid medication like levothyroxine, necessitating monitoring and potential dose adjustments. [18, 19]
It's important to note that many users distinguish the thyroid cancer risk as specifically related to MTC, which is rare, and that rodent studies may not directly translate to human risk. [1, 17, 20] Some recent studies are also cited as providing reassurance regarding the short-term safety concerning general thyroid cancer risk.
Thyroid Cancer Risk & Concerns:
- Medullary Thyroid Carcinoma (MTC) as a Primary Concern: Many users and some medical professionals in the threads highlight that the main contraindication regarding thyroid cancer is a personal or family history of Medullary Thyroid Carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN2).
Thyroid Nodules and Goiter:
- One user on Mounjaro for about two years developed a "giant fluid filled cyst" and a "multi-nodule goiter" leading to a total thyroidectomy.
Impact on Existing Thyroid Conditions (Graves', Hashimoto's, Hypothyroidism):
- Graves' Disease: One user with Graves' in remission since 2022 reported coming out of remission in 2024 after taking Tirzepatide 2.
Thyroid Storm/Hyperthyroidism:
- One severe case mentioned involved a Type 1 Diabetic patient who developed pancreatitis, DKA, and subsequently, previously undiagnosed hyperthyroidism among other complications.
Remedies and Preventions Recommended:
- Discontinuation/Caution with MTC History: The primary prevention discussed is avoiding GLP-1s if there's a personal or family history of Medullary Thyroid Carcinoma or MEN2.
It's important to note that many users distinguish the thyroid cancer risk as specifically related to MTC, which is rare, and that rodent studies may not directly translate to human risk. [1, 17, 20] Some recent studies are also cited as providing reassurance regarding the short-term safety concerning general thyroid cancer risk.