Hypothyroidism and goiter in a patient during treatment with interleukin-2

The development of transient hypothyroidism and goiter in a patient with a metastasized malignant melanoma during treatment with recombinant interleukin-2 (rIL-2) and dacarbazine is reported. Signs of autoimmune thyroiditis became apparent 2 weeks after the start of treatment and disappeared after treatment stopped. It is likely that rIL-2 was responsible by interfering with preexisting autoimmune thyroid disease. The possible mechanisms are discussed here. Patients with positive antithyroid microsomal antibody titers are prime candidates for rIL-2-induced thyroiditis.