Corey Schuler, PhD, FNP, CNS & Allison Sayre, MSN, WHNP
Most of the time, symptoms of a common cold are just that. Self-limiting and easily managed. Irritating but transient. Subacute thyroiditis is one of those conditions that sneaks into the exam room wearing the disguise of “just another virus.” At first glance, symptoms like fatigue, body aches, and low-grade fevers feel familiar, but the story quickly becomes more intriguing when the thyroid gets pulled into the plot.
This viral-induced thyroid dysfunction case report explores that exact moment when a “simple cold” unravels into a deeper endocrine mystery, the kind that invites both practitioner and patient to pause, think critically, and co-navigate the next steps with clarity. This is where curiosity meets clinical reasoning. And just as importantly, where patient stories help us widen our lens, and rethink what’s possible when viral triggers, immune function, stress exposure, and thyroid physiology intersect.
So, What is Subacute Thyroiditis?
Subacute thyroiditis is an inflammatory disorder of the thyroid gland. It is most often triggered by viral infections or post-viral immune dysregulation. This disorder typically presents with anterior neck pain, fever, fatigue, and a transient thyrotoxic phase followed by hypothyroidism before eventual resolution. [1][2]
This case report highlights the diagnostic complexity and symptom variability of subacute thyroiditis, particularly when symptoms overlap with common viral conditions, chronic infections, and stress-related immune suppression.
Case Report
Patient Presentation
A 45-year-old woman with a history of chronic Lyme disease (well-managed natural lifestyle and supplementation) and past mononucleosis initially presented with what she believed was a “common cold.” Her primary symptoms included:
- Fatigue, described as her main concern
- Mild fevers or a persistent “hot feeling,” atypical but noticeable
- Maxillary facial pain, suggestive of sinus involvement
- Sore throat, assumed to be post-nasal drip or possibly streptococcal pharyngitis
- Three weeks of persistent illness, prompting evaluation
Given the presence of facial pain, extended symptom duration, and past tolerance to doxycycline, her practitioner suggested an empirical antibiotic trial for coverage for suspected sinus infection or Lyme flare. Reasonable clinical rationale.
Evolution of Symptoms
Several days later, the patient developed significant right-sided neck pain, an unusual and unexpected symptom that prompted reassessment. Because she also has a history of aphthous stomatitis, she also considered an esophageal ulceration as a possible cause of this pain.
During a follow-up visit with a different practitioner at the practice, the pieces suddenly came together. The practitioner immediately noted her recent illness, recognizing the potential for post-viral thyroid inflammation. Due to the combination of a three-week history of viral-like symptoms and new focal neck pain, the clinician suspected subacute thyroiditis. With new information comes improved clinical rationale.
Laboratory evaluation revealed a markedly abnormal thyroid panel, with TSH, free T3, and free T4 dramatically shifted compared to her normal thyroid values one month prior. A 10-day prednisone taper (starting at 40 mg) was prescribed, aligning with evidence that glucocorticoids offering rapid improvement support the diagnosis; lack of improvement would necessitate reconsideration of the diagnosis.
Differential Diagnosis Considerations
The patient and practitioner reviewed numerous potential causes for her symptoms, creating a teachable illustration of how multifactorial and overlapping symptoms can complicate diagnosis. Considerations included:
1. Viral or Post-Viral Etiologies
- Hand, Foot, and Mouth Disease, due to recent community outbreaks and her volunteer work with children, and coxsackievirus A16 is a potential trigger of inflammation via imbalance of Th1/Th2 and Th17/Treg ratios. However, no cutaneous manifestations were present. [3]
- Epstein–Barr Virus (EBV) reactivation, given her significant prior infection
-
Common cold viruses, which commonly precede subacute thyroiditis
2. Non-Viral Considerations
- Lyme flare, though symptoms did not match her historical patterns
- Esophageal ulceration or infectious pharyngitis, based on throat discomfort
- Stress-related immune suppression, given:
- Multiple recent funerals
- Extensive car travel
- Son experiencing major car trouble out of state
- Work overload and decreased sleep
- The patient initially reported low perceived stress, but further discussion revealed substantial emotional, physical, and circadian stressors, all of which can disrupt natural killer (NK) cell activity and increase susceptibility to viral reactivation. [4]
Symptom Review Supporting Subacute Thyroiditis
Retrospective review of systems revealed multiple findings consistent with transient thyrotoxicosis:
- Increased bowel movement frequency (from 1–2 to 3–4 per day)
- Temperature elevation without obvious fever
- Dry skin
- Palpitations and racing heartbeat, initially attributed to lack of sleep
- Anterior neck pain, a classic distinguishing symptom
Together, these signs reinforced the clinical picture of subacute thyroiditis. [1][5]
Management and Follow-Up Plan
After initiating short-term oral steroids, the practitioner emphasized:
Acute Management
- Monitoring for symptom improvement within several days, as failure to improve would warrant re-evaluation.
- Low-glycemic Load Diet. Glucocorticoids decrease peripheral insulin sensitivity, increase hepatic gluconeogenesis, trigger insulin resistance on the level of the lipid metabolism and adipose tissue, as well as inhibit pancreatic insulin production and secretion increasing the risk of provoking the development of hyperglycemia. [6][7]
Long-Term Monitoring
Because subacute thyroiditis can progress through multiple thyroid states (hyperthyroid → euthyroid → hypothyroid → recovery), the practitioner recommended:
- Thyroid panel testing every 6 months, increased from previous multi-year intervals, until stability is achieved
- Assessment for persistent hypothyroidism, which develops in a subset of cases [1][5]
Supportive and Preventive Focus
Given her history of chronic infections and stress-related immune vulnerability, the care plan included:
- Supporting Natural Killer (NK)-cell function. NK cells are frontline antiviral defenders that help regulate the early antiviral and inflammatory response that often initiates conditions such as subacute thyroiditis, promoting a more efficient resolution of tissue injury. By optimizing NK cell activity, the immune system can clear triggers more effectively while reducing the risk of prolonged or excessive thyroid inflammation. [4][8]
- Addressing chronic stressors more proactively. Reducing and managing stress is important in subacute thyroiditis, as stress can amplify inflammatory signaling and hypothalamic-pituitary-adrenal (HPA)–thyroid axis disruption, potentially worsening symptoms such as fatigue, palpitations, and mood changes. [9][10] By lowering physiologic stress load, patients can support more efficient resolution of inflammation and stabilize thyroid hormone fluctuations during recovery.
- Optimizing Immune Function. Subacute thyroiditis is often driven by a dysregulated inflammatory response, and a well-regulated immune system can help resolve viral-triggered inflammation more efficiently. Supporting balanced immune activity may also reduce the intensity and duration of thyroid tissue injury, promoting a smoother recovery and more stable thyroid hormone levels. [2][5]
Conclusion
Subacute thyroiditis often unfolds in unexpected ways, especially when it follows a lingering viral illness or a period of high stress. This case highlights how easily symptoms can be misread, and how quickly clarity emerges when the practitioner and patient pause, get curious, and work together. Additionally, the case underscores that symptom patterns in thyroid disorders can be erratic and counterintuitive, often dismissed or attributed to benign causes until an inflection point (such as acute neck pain) prompts reevaluation. Understanding the natural phases of subacute thyroiditis helps set expectations, guide monitoring, and reduce the fear that comes with sudden changes in energy, temperature, heart rate, or mood. It is entirely possible that persistent hypothyroidism could have begun while overcoming a viral load, whether it was clinically managed or not.
With shared decision-making at the center, patients feel informed rather than overwhelmed, and practitioners can tailor care as the thyroid moves through its hyper-, hypo-, and recovery phases. Even though the process can test patience, most individuals fully recover, especially when immune and stress physiology are supported along the way. Healing is absolutely possible. And when both sides of the stethoscope stay engaged, curious, and collaborative, the journey becomes less confusing and far more empowering.
Disclaimer:
The information provided is for educational purposes only. Consult your physician or healthcare practitioner if you have specific questions before instituting any changes in your daily lifestyle including changes in diet, exercise, and supplement use.
Allison Sayre is a board-certified women’s health nurse practitioner with advanced expertise in hormonal health, integrative gynecology, and patient-centered care across the lifespan. She holds a Master of Science in Nursing and has served as both a clinical provider and educator in functional and conventional women’s health settings. At ARG, Allison contributes to medical education, clinical protocol development, and strategic content that supports the evolving needs of women's healthcare practitioners.
Corey Schuler, PhD, FNP, CNS has dedicated his career to advancing the science and clinical art of integrative medicine and serves as director of medical affairs for Allergy Research Group. He is a family nurse practitioner and practices holistic primary care at Synergy Family Physicians in White Bear Lake, Minnesota.