From the Research
COVID-19 infection can potentially affect Thyroid-Stimulating Hormone (TSH) levels in hypothyroid patients, though the impact varies between individuals. The most recent and highest quality study, published in 2025, suggests that SARS-CoV-2 infection can lead to thyroid dysfunction and long-term sequelae 1. During acute COVID-19 infection, some hypothyroid patients may experience temporary fluctuations in their TSH levels, which could necessitate adjustments to their levothyroxine dosage. These changes occur because severe illness and inflammatory responses can alter thyroid hormone metabolism and the hypothalamic-pituitary-thyroid axis. The virus may directly affect thyroid tissue through ACE2 receptors or trigger autoimmune responses that impact thyroid function.
Key Findings
- A study published in 2021 found that TSH levels were lower in patients with COVID-19, especially in those with severe disease 2.
- Another study published in 2021 found that low free triiodothyronine (FT3) levels were associated with increased risk of in-hospital mortality in patients with COVID-19 3.
- A study published in 2021 also found that FT3 concentration was significantly lower in patients with severe COVID-19 than in non-severely ill patients, and reduced FT3 independently predicted all-cause mortality of patients with severe COVID-19 4.
Recommendations
- Patients with hypothyroidism who contract COVID-19 should monitor for symptoms of thyroid imbalance such as unusual fatigue, heart palpitations, or temperature sensitivity.
- It's advisable for these patients to have their TSH levels checked after recovering from COVID-19, especially if they notice changes in their symptoms.
- However, patients should continue taking their prescribed thyroid medication during COVID-19 illness unless directed otherwise by their healthcare provider, as maintaining proper thyroid function is important for overall recovery from the infection.
- Evaluation of thyroid function is important in COVID-19 patients, and improving the efficacy of treatment against acute SARS-CoV-2 infection can reduce the risks of short-term and long-term complications 1.