From the Guidelines
GLP-1 receptor agonists can be safely used in patients with hypothyroidism, as they do not interfere with thyroid function or levothyroxine absorption when properly timed. These medications, which include semaglutide, liraglutide, dulaglutide, and tirzepatide, work by slowing gastric emptying, increasing satiety, and improving insulin sensitivity, which helps with weight management without negatively impacting thyroid hormone levels 1. For patients taking both levothyroxine and a GLP-1 agonist, it's recommended to separate the medications by at least 30-60 minutes to avoid potential absorption issues. Levothyroxine should be taken on an empty stomach in the morning, while GLP-1 agonists can be administered later in the day. Some patients with hypothyroidism may actually benefit from GLP-1 therapy, as both conditions often co-occur with obesity and metabolic disorders.
Key Considerations
- Regular monitoring of thyroid function tests remains important when starting any new medication regimen, but no specific dose adjustments of either medication are typically needed when used together.
- GLP-1 receptor agonists have been associated with thyroid C-cell tumors in rodents in a dose- and treatment duration-dependent fashion, but this risk is not well established in humans 1.
- Autoimmune thyroid disease is the most common autoimmune disorder associated with diabetes, occurring in 17–30% of patients with type 1 diabetes, and thyroid autoantibodies are predictive of thyroid dysfunction, most commonly hypothyroidism 1.
Clinical Implications
- GLP-1 agonists can be a useful therapeutic option for patients with hypothyroidism and obesity or metabolic disorders.
- Healthcare providers should be aware of the potential benefits and risks of GLP-1 receptor agonists in patients with hypothyroidism and monitor thyroid function tests regularly.
- The use of GLP-1 receptor agonists in patients with hypothyroidism should be individualized, taking into account the patient's specific medical history, comorbidities, and treatment goals.
From the Research
GLP-1 and Hypothyroidism
There is limited research directly linking GLP-1 and hypothyroidism. However, some studies provide insight into the effects of GLP-1 receptor agonists on various health conditions, including type 2 diabetes, which may have indirect implications for hypothyroidism management.
Key Findings
- GLP-1 receptor agonists are effective in lowering A1C and weight in patients with type 2 diabetes, with some agents also showing cardiovascular benefits 2, 3.
- The treatment of hypothyroidism typically involves levothyroxine therapy, with the goal of restoring normal thyroid-stimulating hormone (TSH) levels 4, 5.
- Some patients with hypothyroidism may not respond well to traditional treatment and may require alternative approaches, such as combined therapy with levothyroxine and liothyronine 5.
- GLP-1 receptor agonists, such as semaglutide and liraglutide, have been shown to have kidney-protective effects in patients with type 2 diabetes, which may be relevant for patients with hypothyroidism who are at risk of kidney disease 6.
Potential Interactions
- There is no direct evidence of interactions between GLP-1 receptor agonists and hypothyroidism treatment.
- However, patients with hypothyroidism who are also being treated for type 2 diabetes may benefit from GLP-1 receptor agonist therapy, which can help improve glycemic control and reduce the risk of cardiovascular events 2, 3, 6.
- Further research is needed to fully understand the potential interactions between GLP-1 receptor agonists and hypothyroidism treatment.