Radioactive Iodine-Induced Psychosis

"Ms. T" is a 39-year-old married woman who underwent a right hemithyroidectomy in October 2007 for follicular thyroid cancer. She then underwent a left thyroid lobectomy in March 2008 for thyroid papillary microcarcinoma. Levothyroxine was started after she was found to have an elevated thyroid-stimulating hormone postoperatively at 6.78 microunits/ml. Because of enlarged lymph nodes and suspected residual cancer cells, she received radioactive iodine treatment in May 2008. The next day she developed paranoid delusions that her home was bugged by various electrical devices. She thought her conversations were being recorded, and she insisted that her husband leave his cell phone and other electronic devices in his car. She developed ideas of reference that the headlines in magazines and newspapers were sending her personal messages. The patient had no prior psychiatric history and did not receive a psychiatric evaluation until November 2008, at which time she also had laboratory and imaging studies. Her thyroid-stimulating hormone level, free T4 level, electrolytes, complete blood count, toxicology screen, and brain magnetic resonance imaging were all normal. and brain magnetic resonance imaging were all normal.

At this point, Ms. T was given a diagnosis of radioactive iodine-induced psychotic disorder and was treated with risperidone, 0.5 mg at bedtime. At a follow-up appointment 1 week later, she reported being almost free of any paranoid thoughts or ideas of reference. She was tolerating the medication well, and her affect was much brighter and less guarded. The patient was without psychotic symptoms at a follow-up evaluation 4 months later while continuing to take risperidone.