The nonthyroidal illness syndrome in the non-critically ill patient.
BACKGROUND
The nonthyroidal illness syndrome (NTIS) is a very common clinical entity among hospitalized patients and has been reported in practically every severe illness and acute or chronic stressful event. There is a large body of data associating the presence of NTIS with the severity of the underlying disease. Most of these studies concern intensive care unit (ICU) patients, whereas the non-critically ill patients outside the ICU setting are less well studied.


METHODS
We provide a review of the existing literature focusing on studies examining NTIS in non-critically ill patients and attempt to summarize the pathophysiological pathways underlying the syndrome, its prognostic role, as well as the current intervention studies mainly from a clinical standpoint.


RESULTS
The aetiology of the NTIS is multifactorial and varies among different groups of patients. Experimental and clinical findings suggest that inflammatory cytokines are implicated in the pathogenesis of the syndrome, whereas recent evidence re-evaluate the role of deiodinases in thyroid hormone metabolism not only in the periphery but also in the hypothalamus and the pituitary and thus in the alterations accompanying NTIS. Clinical data examining the effectiveness of thyroid hormone supplementation in NTIS remain controversial.


CONCLUSIONS
As long as there is no clear evidence of benefit from thyroid hormone replacement and until well-designed studies confirm its efficacy, thyroxine supplementation should not be recommended for the treatment of NTIS.
Pappa
Theodora A
TA
Endocrine Unit, Department of Clinical Therapeutics, Alexandra Hospital, Athens University School of Medicine, Athens, Greece.
Vagenakis
Apostolos G
AG
Alevizaki
Maria
M
D016638:Critical Illness; D005067:Euthyroid Sick Syndromes / Q000453:epidemiology / Q000503:physiopathology*; D006801:Humans; D007362:Intensive Care Units; D012720:Severity of Illness Index; D013961:Thyroid Gland; D013963:Thyroid Hormones / Q000097:blood / Q000378:metabolism*
D013963:Thyroid Hormones