SAT-467 A Case of Pituitary Hyperplasia Secondary to Uncontrolled Primary Hypothyroidism

Abstract

17 year old female presented for evaluation of galactorrhea of 3 months duration. Patient was diagnosed with papillary thyroid cancer and underwent total thyroidectomy in 2011. She was prescribed Synthroid 175 mcg but was not compliant with taking her medicine. In April 2019 she developed bilateral galactorrhea for which she was evaluated at an outside facility and was found to have a prolactin 143.7ng/mL (n 7.2-63) and TSH 996 mIU/L (n 0.5 -4.0). Pituitary MRI revealed pituitary macroadenoma measuring 1.5 x 1.4 x 1.2 cm with slight elevation of the optic chiasm and infundibulum. She was advised to restart Synthroid and was referred for the neurosurgery team at our facility for surgical resection of pituitary macroadenoma. Over the same period of time, she gained 25 lbs, developed headaches, excessive fatigue, constipation, hair loss, lower extremity swelling, and puffiness of her face. Her menstrual cycles were regular but this was only after she was placed on norelgestromin/ ethinyl estradiol transdermal patch. She denied visual changes. By the time she was seen at our clinic in June 2019, she was taking Synthroid daily for 1 month. TSH decreased to 1.0 mIU/L and prolactin improved to 68 ng/mL. IGF-1 was low at 98 ng/mL (n 149-509). ACTH, morning cortisol, and 24 hour urine free cortisol were within reference range. Visual field testing showed no visual defects. We advised patient to continue taking Synthroid and to follow up in 1 month. On the follow up visit in July 2019, TSH was 0.2 mIU/L, prolactin was 52 ng/mL and IGF-1 was 105 ng/mL. Pituitary MRI showed pituitary hyperplasia that has decreased compared to previous MRI, now measuring around 1 cm at the largest dimension without contact with the optic chiasm and the Infundibulum was at midline. Galactorrhea and headaches resolved and fatigue significantly improved.