The burden of comorbidity and the C-reactive protein levels in nonthyroidal illness syndrome with metabolic syndrome and atherosclerosis-related cardiovascular complications.

Thyroid hormones undergo significant modifications during severe illnesses, and the low T3 levels are the hallmark of nonthyoidal illness syndrome (NTIS), due to a reduced extrathyroidal conversion from T4. We examined 41 patients with NTIS by a modified cumulative illness rating scale (CIRS) and the measurement of FT3, FT4, TSH, and C-reactive protein (CRP) levels. Fifty-seven control subjects were enrolled. We observed reduced FT3 and increased FT4 levels in NTIS patients (P < 0.05). The CIRS scores (severity and comordity index) were inversely related to FT3 and positively related to FT4 levels (P < 0.05). The CRP and the FT4 concentrations were positively associated (P < 0.01). Our study showed that the reduced FT3 and increased FT4 levels were significantly related to the comorbidity and severity of systemic illnesses, probably as a result of impairment in the peripheral hormonal conversion. The CIRS scale and the CRP are useful tools for a better evaluation of these patients.