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Sick-euthyroid syndrome

Last edited: 4/23/2026

Overview

Sick-euthyroid syndrome refers to a condition where patients exhibit signs of thyroid hormone imbalance despite having normal thyroid function tests, often observed in critically ill or hospitalized individuals 1.

Diagnosis

  • Elevated free-thyroxine index (FTI) without overt hypothyroidism or hyperthyroidism 1.
  • Consider measuring FTI in elderly inpatients to identify subclinical changes 1.
  • Evaluate for potential drug-induced effects, particularly from L-Dopa, digoxin, and co-trimoxazole 1.
  • Management

  • Identify and manage underlying medications contributing to elevated FTI, such as adjusting doses of L-Dopa, digoxin, or discontinuing co-trimoxazole if possible 1.
  • No specific first-line pharmacological treatment for sick-euthyroid syndrome is indicated based on current evidence 1.
  • Focus on supportive care and management of the underlying illness 1.
  • Special Populations

  • Elderly: Elevated FTI is notably common in elderly inpatients, often linked to medication side effects 1.
  • Key Recommendations

  • Evaluate elderly hospitalized patients for elevated free-thyroxine index, considering potential drug side effects like those from L-Dopa, digoxin, and co-trimoxazole (Evidence: Moderate) 1.
  • Adjust or discontinue medications known to affect thyroid hormone levels if they are contributing to the elevated FTI (Evidence: Moderate) 1.
  • Prioritize supportive care and management of the primary illness rather than specific thyroid interventions (Evidence: Expert opinion) 1.
  • References

    1 Baruch AL, Davis C, Hodkinson HM. Causes of high free-thyroxine index values in sick euthyroid elderly patients. Age and ageing 1976. link

    Original source

    1. [1]
      Causes of high free-thyroxine index values in sick euthyroid elderly patients.Baruch AL, Davis C, Hodkinson HM Age and ageing (1976)

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