Abstract
Alternating hypothyroidism and hyperthyroidism is a rare phenomenon, especially among pediatric patients. It is usually related to simultaneous, unbalanced presence of stimulating and blocking thyroid stimulating hormone receptor antibodies (TRAbs). Herein we describe thyroid stimulating hormone (TSH) and thyroid hormone fluctuations in an adolescent boy with negative TRAbs. A 12-year-old healthy boy exhibited alternating thyroid function, with several switches between hypothyroidism and hyperthyroidism during almost six years of follow-up. He had persistently elevated thyroid peroxidase antibodies, while TRAbs were repetitively negative. Due to a mild clinical presentation, most of the time he did not require any medication. This case contributes to the spectrum of alternating hypothyroidism and hyperthyroidism in the pediatric age and raises the question of mechanisms involved in fluctuating thyroid function. Therapeutic decisions should be individualized and guided by clinical manifestations and thyroid function tests, irrespective of the underlying pathophysiology.