Non-thyroidal illness in the ICU: a syndrome with different faces.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing mechanistic concepts without systematic review methodology or original empirical data
PubMed 24845024 · doi:10.1089/thy.2014.0201
What was done
This narrative review synthesized mechanistic and clinical literature regarding non-thyroidal illness syndrome (NTI) in intensive care unit (ICU) patients, comparing the pathophysiological drivers and tissue responses occurring during the acute phase versus the prolonged phase of critical illness.
What was found
The abstract reports no quantitative data or statistical estimates. It outlines that acute NTI involves low T3, high reverse T3, low/low-normal thyroxine, and un-elevated TSH driven by altered hormone binding, peripheral uptake, deiodinase activity (type-1 and type-3), and macronutrient restriction. In prolonged critical illness with full feeding, NTI is characterized by suppressed hypothalamic TRH and TSH secretion alongside compensatory tissue responses (upregulated monocarboxylate transporters and type-2 deiodinase). The abstract notes that infusion of hypothalamic releasing factors can reactivate the thyroid axis and induce an anabolic response in prolonged illness.
Why it matters
The review distinguishes acute adaptive endocrine alterations from prolonged neuroendocrine suppression, suggesting clinicians avoid intervening in early fasting-related NTI while highlighting prolonged NTI as a specific target for future randomized trials.
Limits
The paper is a narrative review with no systematic search criteria, quality appraisal of cited literature, or pooled quantitative results. The abstract provides no patient numbers, effect sizes, or trial-based outcome data demonstrating clinical benefit from endocrine intervention.
Cited by
- supports T4 can convert into reverse T3 when a person is under high levels of stress.