Relationship between serum 3,5,3'-triiodothyronine and serum interleukin-8, interleukin-10 or interferon gamma in patients with nonthyroidal illness

In order to further delineate the role of cytokines in the pathogenesis of the low T-3 syndrome, we studied the association between serum T-3 and serum interferon gamma (IFN gamma), interleukin-8 (IL-8) and interleukin-10 (IL-10) in 99 consecutive patients hospitalised because of a wide variety of nonthyroidal diseases; none used drugs affecting thyroid hormone metabolism. Patients were divided in group A (normal serum T-3 and T-4), group B (sub-normal serum T-3 and normal T-4) and group C (sub- normal T-3 and T-4). Serum IFN gamma, IL-8 and IL-10 were not different between group A, B and C (with the exception of a small increase of IFN gamma in group B). Serum T-3 was slightly related to serum IL-8 (r=0.25, p <0.05), but not to IFN gamma and IL-10. Stepwise multiple regression indicated that these serum cytokines were not independent determinants of the variability in serum T-3 The results do not support any role of circulating IFN gamma, IL-8 or IL-10 in the pathogenesis of the low T-3 syndrome during illness.