Can a patient with thyroid disease use Glucagon-like peptide-1 (GLP-1) receptor agonists, such as liraglutide (Victoza) or semaglutide (Ozempic)?

GLP-1 Receptor Agonists in Patients with Thyroid Disease

GLP-1 receptor agonists are absolutely contraindicated only in patients with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2), but can be used with appropriate monitoring in patients with other thyroid conditions including hypothyroidism, hyperthyroidism, and non-medullary thyroid cancers. 1, 2

Absolute Contraindications

The FDA Black Box Warning establishes clear contraindications based on rodent studies showing dose-dependent thyroid C-cell tumors:

• Personal or family history of medullary thyroid carcinoma (MTC) - This is an absolute contraindication per FDA labeling and all major guideline societies 1, 2
• Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) - Absolute contraindication due to increased MTC risk 1, 2

Non-Medullary Thyroid Conditions: Safe with Monitoring

For patients with other thyroid diseases, GLP-1 receptor agonists can be used:

Hypothyroidism and Levothyroxine Use

• Patients on levothyroxine replacement can use GLP-1 RAs but require closer monitoring of thyroid function tests 3
• GLP-1 RAs may alter levothyroxine absorption through delayed gastric emptying, potentially requiring dose adjustments of 25% or more 3
• Monitor TSH levels more frequently during GLP-1 RA initiation and dose titration, as suppressed TSH has been documented in post-thyroidectomy patients 3

Non-Medullary Thyroid Cancer History

• For patients with history of papillary, follicular, or other non-MTC thyroid cancers in complete remission, GLP-1 RAs may be considered after evaluating the risk/benefit ratio 1
• The American College of Cardiology recommends considering time since complete remission and implementing close monitoring with regular thyroid function tests 1
• Randomized controlled trials show thyroid cancer as a rare event without conclusive evidence of increased risk, though observational data are inconsistent 4, 5

Hyperthyroidism, Goiter, and Thyroid Nodules

• No contraindication exists for these conditions - meta-analysis of 45 RCTs showed no significant effect on hyperthyroidism (RR 1.19,95% CI 0.61-2.35), goiter (RR 1.17,95% CI 0.74-1.86), or thyroid mass (RR 1.17,95% CI 0.43-3.20) 5

Critical Monitoring Requirements

When prescribing GLP-1 RAs to patients with thyroid conditions:

• Counsel all patients about thyroid tumor symptoms including neck mass, dysphagia, dyspnea, and persistent hoarseness 2
• Routine serum calcitonin monitoring is NOT recommended due to low test specificity and high background thyroid disease incidence, which increases unnecessary procedures 2
• If calcitonin is measured and >50 ng/L, further evaluation is warranted as this may indicate MTC 2
• For patients on levothyroxine, check TSH at baseline, 4-6 weeks after GLP-1 RA initiation, and after each dose escalation 3

Evidence Quality and Nuances

The thyroid cancer risk data present important nuances:

• Rodent data show clear C-cell tumor risk, but human relevance remains undetermined 2, 4
• Recent 2025 comparative effectiveness study found increased thyroid cancer diagnoses within the first year of GLP-1 RA initiation (HR 1.85,95% CI 1.11-3.08), but this likely represents surveillance bias rather than causation, as cases were predominantly small papillary microcarcinomas 6
• Meta-analysis of RCTs shows no significant increase in overall thyroid cancer risk (RR 1.30,95% CI 0.86-1.97) 5
• The 2021 liraglutide study found 67% of thyroid cancers in the liraglutide group were microcarcinomas versus 43% in comparators, with shorter time-to-diagnosis, strongly suggesting detection bias 7

Alternative Medications When GLP-1 RAs Are Contraindicated

For patients with MTC/MEN2 history requiring glucose or weight management:

• SGLT-2 inhibitors provide cardiovascular and renal protection 1
• Metformin remains first-line therapy 1
• DPP-4 inhibitors are safe alternatives 1
• Insulin therapy when needed 1

Common Pitfalls to Avoid

• Do not withhold GLP-1 RAs from patients with non-MTC thyroid disease based on unwarranted concerns - the evidence does not support this restriction 4, 5
• Do not order routine calcitonin screening - this creates more harm through false positives and unnecessary procedures 2
• Do not assume new thyroid nodules found after GLP-1 RA initiation are caused by the medication - these likely represent detection bias from increased surveillance 6, 7
• Do not forget to adjust levothyroxine doses when initiating GLP-1 RAs in hypothyroid patients 3