Clinical Significance of Free Triiodothyronine Levels in Autoimmune Encephalitis

Overview

This study investigates the role of low triiodothyronine (T3) syndrome in patients with antibody-negative autoimmune encephalitis (AE). It finds that low T3 syndrome is common and reflects disease severity.

Background

Autoimmune encephalitis (AE) is a serious inflammatory disorder of the central nervous system, often presenting with non-specific symptoms that complicate diagnosis. A significant number of patients remain antibody-negative, leading to challenges in treatment and prognostic assessment. Identifying reliable biomarkers for disease severity is crucial.

Data Highlights

Key Findings

• 23.68% of patients with antibody-negative AE presented with low T3 syndrome.
• Patients with low T3 syndrome had a higher incidence of consciousness disturbances (p = 0.048).
• Low T3 syndrome was associated with more frequent motor impairments and higher modified Rankin Scale (mRS) scores during hospitalization.
• Discharge mRS was identified as an independent predictor of unfavorable outcomes (OR 0.293, p = 0.021).
• 8 out of 84 patients (9.5%) were reclassified with alternative diagnoses during follow-up.

Clinical Implications

The presence of low T3 syndrome in antibody-negative AE may indicate greater disease severity, but it should not be solely relied upon for prognostic predictions.

Conclusion

Low T3 syndrome is prevalent in antibody-negative AE and correlates with disease severity, but it does not serve as an independent prognostic marker.

Related Resources & Content

1. Frontiers | Clinical implications of free triiodothyronine levels and diagnostic revisions in antibody-negative autoimmune encephalitis
2. Canadian Consensus Guidelines for the Diagnosis and Treatment of Autoimmune Encephalitis in Adults
3. A clinical approach to diagnosis of autoimmune encephalitis - PMC
4. The Journal of Clinical Endocrinology & Metabolism — A Prospective, Blinded Investigation of Thyrotropin Receptor Antibodies in Autoimmune Thyroid Disorders Conducted in the United States
5. The Journal of Clinical Endocrinology & Metabolism — Significance of Thyroid-Stimulating Immunoglobulin and Thyrotropin Receptor Antibody in Graves Disease
6. Frontiers in Neurology — Middle-aged predominance and diagnostic delays in anti-LGI1 encephalitis: the role of antibody testing
7. Frontiers in Endocrinology — Behavior of serum thyroglobulin in relation to thyroid function under low-thyrotropin conditions in general practice
8. A clinical approach to diagnosis of autoimmune encephalitis - PMC
9. Canadian Consensus Guidelines for the Diagnosis and Treatment of Autoimmune Encephalitis in Adults
10. Frontiers | Clinical implications of free triiodothyronine levels and diagnostic revisions in antibody-negative autoimmune encephalitis