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 T3 syndrome, we studied the association between serum T3 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 T3 and T4), group B (subnormal serum T3 and normal T4) and group C (subnormal T3 and T4). 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 T3 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 T3. The results do not support any role of circulating IFN gamma, IL-8 or IL-10 in the pathogenesis of the low T3 syndrome during illness.