Related case report: In vivo suppression of thyrotropin by 9-cis retinoic acid

Treatment of a 48-year-old woman with advanced cervical cancer with the syn thetic vitamin A derivative, 9-cis retinoic acid (9cRA), resulted in thyroi d-stimulating hormone suppression without clinical evidence of thyrotoxicos is, which resolved spontaneously when the drug was withdrawn. 9cRA, which i s a pan-retinoid (RAR and RXR) agonist, has preciously been implicated in i nduction of interactions between the thyroid receptor and the retinoid rece ptor, RXR,with endocrine target organ specificity. Furthermore, 9cRA has be en shown to downregulate thyroid-stimulating hormone messenger RNA in a pit uitary-specific fashion in a murine model, a finding consistent with the pi tuitary-restricted thyrotoxicosis observed in our patient. This is the firs t reported case of thyroid-stimulating hormone suppression by 9cRA and sugg ests that patients receiving this agent should be monitored for pituitary a nd thyroid function abnormalities.