Iatrogenic hyperthyroidism secondary to dextrothyroxine administration.

ABSTRACT

Two patients are reported who presented with clinical hyperthyroidism, increased serum thyroid function studies, and depressed radioactive iodine uptake, secondary to chronic ingestion of D-T4. Symptoms abated, and function studies returned to normal, following discontinuation of D-T4. This uncommon effect of D-T4 may be more prevalent than is generally realized and must be recognized as another potential cause of low radioiodine uptake in patients with clinical hyperthyroidism.