Transient hyperthyroidism in patients with lymphocytic thyroiditis.

We have studied seven episodes of transient hyperthyroidism in three men and one woman, aged 19 to 38 years. No patient had fever or neck tenderness. All had palpable thyroid glands. Elevated serum thyroxine values persisted for 1 to 3 months. Thyroid131I uptake at 6 and 24 hours was low (1 to 3%). Erythrocyte sedimentation rates were normal or only slightly increased. Needle biopsy in four patients and a thyroidectomy specimen in one patient, all taken during the hyperthyroid phase, showed lymphocyte infiltration and extensive follicular disruption without oxyphilia. There was no evidence of granulomatous thyroiditis. Thyroglobulin antibodies were normal in all. In three patients, transient hypothyroidism followed the hyperthyroid episode. In two patients, the condition was recurrent. The findings are compatible with transient unregulated discharge of thyroid follicle content in some patients with lymphocytic thyroiditis. Recognition permits avoidance of unnecessary treatment with surgery, radioiodine, or antithyroid drugs.