Can Lyme Disease Affect the Thyroid? What to Know About Thyroiditis
Can Lyme disease affect the thyroid? In rare cases, infection with Borrelia burgdorferi has been associated with autoimmune thyroiditis—raising important questions about how infection may influence immune function.
Lyme disease and thyroid problems may occasionally occur together, particularly when infection triggers inflammation affecting multiple systems.
In the article “Coexisting Thyroiditis and Carditis in a Patient with Lyme Disease: Looking for a Unifying Diagnosis,” Zarghamravanbakhsh and colleagues describe a patient who developed both thyroiditis and Lyme carditis.¹
The case involved a 53-year-old woman who developed symptoms shortly after returning from a trip to Delaware. Although she did not recall a tick bite, she reported multiple encounters with deer during her visit.
Within days she developed headaches, heat intolerance, near-syncope, and a 5 × 5 cm rash on her chest. One week later, her symptoms progressed to include shortness of breath on exertion and palpitations.
She was diagnosed with Lyme carditis after her ECG showed a first-degree AV block.
Lyme Disease and Thyroid Test Abnormalities
The patient also had abnormal thyroid laboratory results, including elevated free thyroxine (T4) and low thyroid-stimulating hormone (TSH).
Her TSH level had been normal four months earlier.
Thyroid peroxidase antibodies were present, while thyroid-stimulating immunoglobulin was not.
“Her iodine-123 thyroid scan and 24-hour uptake showed a decrease in iodine uptake of 1.2%, consistent with thyroiditis,” wrote the authors.
The patient was treated with intravenous ceftriaxone followed by a 3-week course of doxycycline.
Testing for Lyme disease using Western blot was positive.
Following antibiotic treatment, the patient’s thyroid function tests normalized—suggesting that infection may have contributed to thyroid inflammation.
Can Lyme Disease Trigger Autoimmune Thyroiditis?
The authors concluded that autoimmune thyroiditis may be linked to Lyme disease in some cases.
This raises a broader clinical question: can infection trigger immune-mediated conditions?
Similar patterns are explored in Lyme disease and autoimmune arthritis, where infection and immune activation may overlap.
These interactions may reflect underlying persistent Lyme disease mechanisms, including immune dysregulation and inflammatory responses.
Evidence Linking Lyme Disease and Thyroiditis
Several earlier reports have described thyroid abnormalities in patients with Lyme disease:
- Paparone described Lyme disease in a patient with primary hypothyroidism
- Dhliwayo and colleagues reported transient thyrotoxicosis with decreased iodine uptake
- Deol and colleagues described an association between Lyme disease and thyroiditis
In this case, the authors noted that known exposure, a classic rash, and normalization of thyroid function after treatment supported a link between Lyme infection and thyroid inflammation.
Important Clinical Considerations
Although Lyme disease may occasionally affect the thyroid, other explanations must be considered.
Thyroid disease itself can produce false-positive Lyme serology and may also cause cardiac conduction abnormalities.
Careful evaluation is essential. Clinicians must determine whether findings reflect infection, autoimmune thyroid disease, or another condition.
Clinical Takeaway
Lyme disease may rarely be associated with autoimmune thyroiditis. In some patients, infection and immune activation may overlap.
Thyroid abnormalities in Lyme disease require careful interpretation. Not all findings are caused by infection, and evaluation should consider multiple possibilities.
When symptoms span multiple systems—such as cardiac and endocrine—broader pattern recognition can help guide diagnosis.
Related Articles:
Lyme carditis presenting as atrial fibrillation treated successfully
Another cardiac manifestation of Lyme myocarditis
Lyme myocarditis in patient with no other signs of Lyme disease
References:
- Zarghamravanbakhsh P, et al. Coexisting Thyroiditis and Carditis in a Patient With Lyme Disease: Looking for a Unifying Diagnosis. AACE Clin Case Rep. 2022;8(4):150-153.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
December 27 2022
I’ve had autoimmune thyroid for over 30 years. My heart was bugging me a lot. Low blood pressure. Tachycardia.
Wasn’t diagnosed with lyme till 3 years ago. By then, my legs were going. I kept fainting.
Still not feeling great.
I used to be a body builder
L. Cassel
I’ve had LD since 1985. Diagnosed in 1999…and I have hypothyroidism. And had low BP for many years, and just recently Diagnosed with HIGH BP! I have had lyme disease for years. Almost every symptom, and misdiagnosed with MS…like many others..thank God I was smart and was able to find a LLMD to get the right treatment.
Dr Cameron
Another good article. We’ve talk before. My symptoms just keep getting worse. As of late obgyn say my right ovary has a cyst that has grown from 2.5 cm-4 cm. Dr says there is plenty of blood flow in the ovary. Cyst looks like a black whole. Have much pain both ovaries but left was not seen on ultrasound do to prolapse in vaginal wall, bladder and bowel. I’m curious to know what a cyst filled with Lyme or babesia
Would look like.
Also, the night sweats from babesia has turned to day in and day out sweats. Husband gave me a hug during one of these sweat episodes and said honey go take a shower that sweat doesn’t smell right. Made me feel really bad but I understood what he was saying.
Can you please say something that will help me out. Reminder dx with Lyme and babesia in 2007. Had to rounds of doxycycline for treatment. Period.
The cysts that are discussed in Lyme disease a typically microscopic. I advise my patients with visible cysts to have them evaluated. I also advise treatment for Babesia with a drug combination such as atovaquone and azithromycin in case Babesia is the cause of their illness.