[Factitious hyperthyroidism caused by L-thyroxin abuse. Case report]

A 43 years old female was treated for 8 months with antithyroid drugs because of a difficult adjustable hyperthyroidism. In spite of this massive antithyroid therapy a threatening deterioration of the clinical picture occurred. The reason for it was the secret intermittent intake of up to 1200 micrograms lT4 daily motivated by private problems. The difficulties of a differential diagnosis between a thyrotoxicosis factitia and an endogenous hyperthyroidism is stressed. One should always consider a thyrotoxicosis factitia in the case of suggestion of a psychopathia and when thyroid hormone medication is used for suppressive thyroid hormone therapy or as a prophylaxis of goiter recurrence. In addition overweight, major personality disorders and resistance to antithyroid drugs are indicative for thyroid hormone abuse. Important indicators for the differentiation between a thyroid hormone abuse and an endogenous hyperthyroidism are a lack of technetium- or radioiodine-uptake in the thyroid and suppressed levels of thyroglobulin.