Keywords
Sick Euthyroid Syndrome
Non-thyroidal Illness Syndrome
Low T3 Syndrome
Thyroid hormones
How to Cite
Abstract
Heart failure (HF) is a significant disease burden and mortality worldwide and is often accompanied by endocrine changes that affect the disease course. One of these is Sick Euthyroid Syndrome (SES), or Non-thyroidal Illness Syndrome (NTIS) which is a decrease in serum levels of triiodothyronine (T3) in the absence of any thyroid disease. This literature review will review the current evidence of the role of SES as a prognostic marker and its role as a therapeutic target in patients with heart failure. A thorough literature review was done with the predefined search terms of heart failure, SES, thyroid hormone dysfunction, prognosis, and thyroid hormone replacement therapy, in major databases. Relevant clinical studies were reviewed and synthesized narratively to examine clinical thyroid function, clinical outcomes, and therapeutic interventions. The evidence on hand is consistently associated with the association between low T3 levels with increased severity of disease, impaired cardiac function, hospitalisation and mortality. Free T3, reverse T3, the FT3/FT4 ratio and NT-proBNP also seem to be useful biomarkers in risk stratification. The results of thyroid hormone replacement in selected hemodynamic and functional parameters in different experimental and small clinical studies have been inconclusive and need further study before it can be recommended as a routine therapy. SES is a clinically relevant indicator of poor prognosis in patients with heart failure and it highlights the intricate relationship between thyroid hormone metabolism and heart failure pathophysiology. More good clinical studies are needed to better define its therapeutic value and clarify its role in the therapy of heart failure patients.
References
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