Lithium-induced thyrotoxicosis in a patient with treatment-resistant bipolar type I affective disorder
In June 2012, a 19-year-old woman presented to an emergency department with a 2-week history of headaches, lethargy, 2 kg weight loss and tremor. Her medical history included treatment-resistant bipolar type I affective disorder, subclinical hypothyroidism and polycystic ovarian syndrome. Her medications included lithium carbonate 1250 mg daily, quetiapine 1000 mg daily, chlorpromazine 200 mg daily, cyproterone acetate/ethinyloestradiol 2 mg/35 µg daily, cholecalciferol 1000 IU daily, and lorazepam 1 mg at night for insomnia as needed. She had not been given an iodine-containing contrast medium, and she reported that she had not been taking thyroxine and that she had not ingested excessive amounts of iodine or kelp. She had no history of ocular symptoms. Her paternal grandmother had had a thyroidectomy.
In April 2010 (several months after commencing lithium therapy), she had developed subclinical hypothyroidism. Results of serum tests showed an elevated thyroid-stimulating hormone (TSH) level of 5.94 mIU/L (reference interval [RI], 0.4–3.5 mIU/L) and a normal free thyroxine (FT4) level of 12.8 pmol/L (RI, 9.0–19.0 pmol/L). This had resolved spontaneously within months.
On presentation at the emergency department, the patient was afebrile and tachycardic with a heart rate of 120 beats/min.…