Increased serum interleukin‐1bT during treatment of zhyperthyroidism with antithyroid drugs

Serum interleukin‐1bT (IL‐1bT) and soluble interleukin‐2 receptor (sIL‐2R) levels were examined in patients with hyperthyroidism due to Graves' disease (GD) and toxic nodular goitre (TNG) before and during antithyroid drug therapy. A total of 32 patients were studied; 23 patients (14 with GD and nine with TNG) were in a hyperthyroid state (group A) and nine patients (four with GD and five with TNG) were in a euthyroid state, under carbimazole or methimazole treatment (group B). Ten hyperthyroid patients from group A (seven with GD and three with TNG) were also examined while euthyroid on treatment (Subgroup A). Serum was taken from all patients for the measurement of sIL‐2R, IL‐1bT, total T 4 (TT 4 ), total T 3 (TT 3 ) and TSH concentrations. The results were compared with those from 30 normal controls. Serum sIL‐2R levels were higher in Group A (671–3 pM 74–0 UmlT ‐1 , meaniSE), than in Group B (214–1 pM 61–8UmL ‐1 ) and controls (149pm 14–8 Umr ‐1 ), P< 0–001. Similarly, the subgroup of 10 patients had higher levels of sIL‐2R during the hyperthyroid phase than while euthyroid (P < 0001). There was a positive correlation between sIL‐2R values and levels of T 4 and T 3 . In contrast, serum IL‐1bT levels were higher in Group B patients (197–5pM 39–2 pg mL ‐1 ) compared with those in Group A (66–5pM17pgmL ‐1 P<0–01). IL‐1bT levels were also higher in Subgroup A patients during the euthyroid than in the hyperthyroid phase of their disease (P<0005). In comparison with controls mean IL‐1bT levels were higher in both groups (A and B) of patients (P<005 and P<0002, respectively). It is concluded that serum IL‐1bT, as well as sIL‐2R is elevated in hyperthyroid patients. During treatment with antithyroid drugs sIL‐2R returns to normal, but IL‐1bT increases further. The latter changes may indicate a role for IL‐1bT in mediating antithyroid drug action.