Annals of Case Reports and Clinical Studies (ISSN: 2834-5673) | Volume 5, Issue 5 | Case Report | Open Access DOI

Concurrent Thyrotoxicosis-Induced Atrial Fibrillation and Seropositive Rheumatoid Arthritis Masquerading as Urinary Sepsis: A Case Report

Shaun Nevil*

Aditi Balan1, Pragna Yandrathi2, Ishant Aggarwal3, Pranjal Patil4, S Anton Charles5, Shaun Nevil6*, Chaitra C S7

1ACS Medical College and Hospital, Chennai, Tamil Nadu, India

2Common Wealth University College of Medicine, St. Lucia, India

3All India Institute of Medical Sciences, Gorakhpur, India

4Dr. Vaishampayan Memorial Government Medical College, Solapur, Maharashtra, India

5Department of Internal Medicine, ESIC Medical College PGIMSR & Model Hospital, Bengaluru, India

6Department of Internal Medicine, ESIC Medical College PGIMSR & Model Hospital, Bengaluru, India

7Department of Internal Medicine, ESIC Medical College PGIMSR & Model Hospital, Bengaluru, India

*Correspondence to: Shaun Nevil 

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Abstract

Autoimmune thyroid disease and rheumatoid arthritis (RA) share overlapping immunogenetic pathways, but their simultaneous, fulminant onset is rarely reported and can be mistaken for sepsis. A 68-year-old previously healthy woman presented with fever, chills, polyarthralgia, and an irregular pulse of 160 beats/min, initially diagnosed as urinary sepsis with hyponatremia. Work-up revealed suppressed thyroid-stimulating hormone (TSH) with elevated free T3/T4 and atrial fibrillation with fast ventricular response, alongside positive anti-cyclic citrullinated peptide antibody, rheumatoid factor, and elevated erythrocyte sedimentation rate, confirming synchronous thyrotoxicosis and seropositive RA. She improved with rate control, anticoagulation, carbimazole, and disease-modifying antirheumatic drugs (DMARDs). Autoimmune emergencies can closely mimic infection, a high index of suspicion and multidisciplinary management are essential to prevent cardiovascular and metabolic decompensation.

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Citation:

Aditi Balan, Pragna Yandrathi, Ishant Aggarwal, Pranjal Patil, S Anton Charles, Shaun Nevil, et al. Concurrent Thyrotoxicosis-Induced Atrial Fibrillation and Seropositive Rheumatoid Arthritis Masquerading as Urinary Sepsis: A Case Report. Ann Case Rep Clin Stud. 2026;5(5):1-4.