Non-thyroidal illness syndrome and isolated low triiodothyronine as prognostic markers in acute illness: a systematic review and meta-analysis

To evaluate the association between thyroid hormone alterations and mortality in critically ill and cardiovascular patients, and to compare the prognostic performance of non-thyroidal illness syndrome and isolated low triiodothyronine.

PubMed/MEDLINE, Scopus, and Web of Science were systematically searched for studies published between 2014 and 2026 evaluating thyroid dysfunction and mortality in acute or critical illness. Studies assessing non-thyroidal illness syndrome or isolated low triiodothyronine were included. Random-effects meta-analyses were performed using odds ratios (ORs) with 95% confidence intervals (CIs).