Relation between thyroid hormone concentration and serum levels of interleukin-6 and interleukin-10 in patients with nonthyroidal illness including chronic kidney disease.

Introduction: We evaluated relations between interleukins (IL) IL-6 and IL-10 and euthyroid sick syndrome (ESS) in patients with nonthyroidal illness (NTI).

Materials And Methods: Sixty patients and 20 healthy volunteers were recruited. The patients had either chronic kidney disease (CKD), congestive heart failure (CHF), or acute myocardial infarction (MI), distributed equally in 3 subgroups. Serum levels of IL-6 and IL-10, thyroid stimulating hormone (TSH), total T4, and T3 were determined.

Results: In the 60 patients with NTI, we detected a significantly lower T3 and T4 levels compared to controls, while TSH level was within the reference range. Also, IL-6 level was substantially higher than that in controls (P < .001) and correlated with T3 (r = -0.620, P < .001) and T4 (r = -0.267, P < .001). Similarly was IL-10 level (P < .001) that correlated with T3 (r = -0.512, P < .001), but not with T4. The ILs correlated positively with each other (r = 0.770, P < .001). Only IL-6 was a predictor of low T3 (P = .001). The proportion of patients with subnormal T3, T4, and TSH levels was highest in those with MI along with greatest IL-6 and IL-10 levels compared to patients with CHF and CKD. Patients with CKD showed the least disturbance in IL-6 and IL-10 despite the lower levels of T3, T4, and TSH in a higher proportion of them compared to patients with CHF.

Conclusions: The high frequency of ESS in patients with NTI may be linked to IL-6 and IL-10 alterations. Perturbation of IL-6, and not IL-10, might be involved in the pathogenesis of ESS along with other key players as suggested by our findings in CKD.