Mechanism of Fever in Thyroid Storm
Fever in thyroid storm results from markedly increased tissue thermogenesis and elevated basal metabolic rate (BMR) caused by excessive thyroid hormone action on cellular metabolism. 1
Primary Pathophysiological Mechanism
The fever mechanism operates through direct thyroid hormone effects on cellular metabolism:
- T3 (the active thyroid hormone) binds to nuclear receptors that function as transcription factors, upregulating genes involved in energy metabolism and heat production 1
- Thyroid hormone increases tissue thermogenesis and BMR across nearly every tissue and organ system in the body 1
- This represents an exaggerated manifestation of thyroid hormone's normal physiological effects, amplified to pathological levels in thyroid storm
Additional Contributing Factors
While the primary mechanism is metabolic, other factors may contribute:
- Heightened cellular response to thyroid hormone - The exact mechanisms underlying progression from uncomplicated hyperthyroidism to thyroid storm involve an exaggerated tissue response to thyroid hormone, though these mechanisms remain incompletely understood 2
- Inappropriate generalized immune activation - Evidence suggests markedly elevated soluble interleukin-2 receptor (sIL-2R) levels in thyroid storm, indicating an activated immune response that may play a role in pathogenesis 3
- Multiple organ dysfunction - The fever occurs in the context of multi-organ failure, which itself generates inflammatory mediators 4, 5
Clinical Context
The fever in thyroid storm is:
- Not infectious in origin (though infection may be a precipitating factor)
- Part of the hypermetabolic state that includes tachycardia, altered mental status, and cardiovascular decompensation
- A cardinal diagnostic feature included in both the Burch-Wartofsky and Japanese Thyroid Association scoring systems 5, 6
Important Caveat
Do not confuse thyroid storm fever with subacute thyroiditis, where fever results from viral inflammation of thyroid tissue itself 1. In thyroid storm, the fever is systemic and metabolic, not from thyroid gland inflammation.