minocycline and Hyperthyroidism

Thyroid dysfunction in adolescents treated with minocycline for acne has been previously described as transient effect and/or associated with autoimmune thyroiditis. We report nonimmune-mediated thyroid dysfunction associated with minocycline/doxycycline in 3 adolescents whose clinical courses suggest an adverse effect that may be more common, serious, and persistent than realized previously.

Topics: Acne Vulgaris; Adolescent; Anti-Bacterial Agents; Diplopia; Fatigue; Female; Headache; Humans; Hyperthyroidism; Male; Minocycline; Polydipsia; Thyrotropin; Thyroxine; Weight Loss

We describe a 31-year-old woman who had ingested minocycline for 18 months prior to presenting with hyperthyroidism and a palpable thyroid nodule. There was no evidence of Graves' disease or autonomous nodule on thyroid scintigraphy, and a clinical diagnosis of thyroiditis was made. Fine-needle aspiration biopsy of the palpable lesion suggested papillary carcinoma, and the patient underwent a total thyroidectomy. Intraoperatively, the thyroid gland was found to have a striking black discoloration. Subsequent histological examination revealed the accumulation of pigment globules within the apical cytoplasm of the follicular cells, and associated findings of a drug-induced thyroiditis. The tumor nodule showed features of infarction and was felt to represent a necrotic papillary microcarcinoma. We postulate that in addition to causing black thyroid pigmentation, chronic minocycline use in our patient resulted in thyroiditis and subsequent hyperthyroidism. The papillary microcarcinoma was probably a coincidental finding.

Topics: Acne Vulgaris; Adult; Anti-Bacterial Agents; Carcinoma, Papillary; Female; Humans; Hyperthyroidism; Incidental Findings; Minocycline; Thyroid Gland; Thyroid Neoplasms; Thyroiditis