A51-05 Double Trouble: An Unexpected Cause of Thyroid Storm

Abstract Introduction Thyroid storm is a severe manifestation of thyrotoxicosis, typically precipitated by acute stressors such as trauma or infection. West Nile Virus (WNV) infection, though uncommon, can cause neuroinvasive disease, which is associated with significant morbidity and mortality. We present a case of thyroid storm precipitated by neuroinvasive WNV, suggesting a potential novel viral trigger. Case Presentation A 47-year-old man with hypothyroidism and alcohol use presented after a witnessed ground-level fall with tremulousness and confusion. He was febrile to 39.5 °C, hypertensive (174/95 mmHg), and tachycardic to the 130s. Physical exam revealed encephalopathy, tremulousness, ataxia, and right cranial nerve VI palsy. He was admitted to the ICU for worsening encephalopathy and required intubation. The differential included encephalitis, alcohol withdrawal, and thyroid storm. Serum ethanol was 10 mg/dL, but phosphatidylethanol was elevated (1016 ng/mL), prompting phenobarbital loading for withdrawal management. Head and neck CT were unremarkable. Lumbar puncture revealed clear CSF with WBC 407/µL (84% neutrophils) and normal protein and glucose. Gram stain showed 4+ PMNs. The meningitis/encephalitis panel and WNV PCR were negative, but CSF WNV IgM was elevated (6.72), confirming WNV encephalitis. Thyroid studies showed undetectable TSH (0.01 µIU/mL), markedly elevated T3/T4, and positive thyroid antibodies (Thyroid-stimulating Ig 6.45 0.54, TRAb 6.6 1.75). Neck ultrasound demonstrated diffuse thyromegaly. The Burch-Wartofsky score was 70, highly suggestive of thyroid storm. Although previously diagnosed with hypothyroidism, outpatient labs showed conversion to hyperthyroidism consistent with evolving Graves' disease. Discussion WNV is a mosquito-borne flavivirus that rarely causes neuroinvasive disease, as most cases are asymptomatic. Cerebrospinal Fluid (CSF) findings typically show lymphocytic pleocytosis, though previous studies have shown that more than a third of cases may have neutrophil predominance. CSF WNV IgM is generally preferred over PCR due to its higher reported sensitivity. Several viral infections—including COVID-19, influenza, dengue, mumps, hepatitis B and C, HIV, and EBV—have been reported as triggers of thyroid storm in hyperthyroid patients. Previously proposed mechanisms include viral invasion of thyroid tissue, immune activation, and cytokine-mediated dysregulation of the hypothalamic-pituitary-thyroid axis. While WNV has not been previously associated with thyroid storm, parallels with dengue, another flavivirus, suggest it may act through similar inflammatory pathways. This case highlights the diagnostic complexity of WNV encephalitis and is the first case to link it as a potential cause of thyroid storm. Although alcohol withdrawal can mimic thyroid storm, it does not cause it and was likely an incidental finding in this patient. This abstract is funded by: None