Nonthyroidal illness syndrome: is it far away from Crohn's disease?

This study was designed to investigate the clinical features of nonthyroidal illness syndrome (NTIS) compared with euthyroid patients in Crohn's disease (CD), to explore the etiology of NTIS in CD, to evaluate the clinical outcomes of NTIS patients, and to inspect the correlation of clinical variables and NTIS, and their ability of differentiating NTIS from euthyroid patients.

NTIS has been described for more than 30 years. However, only few studies focused on the relationship between NTIS and CD. The incidence, underlying pathogenesis, clinical outcomes, and correlation with other inflammatory disease severity and nutritional variables of NTIS in CD have not been completely established.

Prospectively, 44 CD patients were enrolled. Medical records and various laboratory values (including thyroidal, nutritional, and inflammatory variables) were collected in all participants.

The incidence of NTIS in CD was 36.4%. Albumin, Acute Physiology and Chronic Health Evaluation II score, and Crohn's Disease Activity Index score in NTIS group were statistically different from those in euthyroid group. A decreased sum activity of deiodinases and a reduced ratio of TT4/FT4 were observed in NTIS group. Duration of hospitalization was significantly longer for NTIS patients than euthyroid patients. Albumin was confirmed as a protective factor of NTIS in CD. Receiver operating characteristic curve analysis demonstrated the differentiating capacity of albumin, suggesting 37.6 g/L as optimal cut-off value with sensitivity and specificity of 81.3% and 79.2%, respectively.

NTIS was a common complication in CD. NTIS patients showed worse nutrition status and clinical outcome, and more critical disease activity and severity compared with euthyroid patients. A hypodeiodination condition and a potential thyroid-hormone-binding dysfunction may play a role in the etiology of NTIS in CD. Albumin was a meaningful protective and distinguishing marker of NTIS in CD.