Proinflammatory cytokine levels in hyperthyroidism

Among suspected causes of the osteoporosis frequently seen in untreated thyrotoxicosis are the osteotrophic cytokines. We studied serum levels of osteotrophic cytokines including interlukin (IL)-1, IL-6, IL-8 and tumour necrosis factor alpha (TNF-alpha) in patients with various hyperthyroid states.

Serum cytokines were detected in 4 groups of

14 patients with Graves' disease, 9 patients with toxic nodular goitre, 27 patients with toxic multinodular goitre and 30 euthyroid control subjects. The levels of IL-1-beta, IL-6, IL-8 and TNF-alpha in the serum were determined by the IMMULITE autoanalyzer, using a chemoilluminesence method.

Compared with euthyroid control subjects, patients with hyperthyroidism had significantly elevated serum levels of IL-8 (506.8 pg/mL v. 7.0 pg/mL, p < 0.001) and TNR-alpha (18.6 pg/mL v. 8.7 pg/mL, p < 0.05). Levels of IL-1-beta (12.2 pg/mL v. 5.0 pg/mL) and IL-6 (30.3 pg/mL v. 5.3 pg/mL) were also higher in controls, but the differences were not statistically significant. Levels of the cytokines were similar in 14 patients with diffuse goitre compared with 36 patients having nodular goitre. Cytokine levels in 20 premenopausal and 20 postmenopausal women with hyperthyroidism were also similar.

We conclude that increased circulating cytokine concentrations observed in patients with hyperthyroidism may derive from the activation of humoral reactions in sites other than the thyroid.