PMON91 Late Presentation of Pituitary Apoplexy Following Gonadotropin-Releasing Hormone Agonist for Prostate Cancer Treatment

BACKGROUND: Pituitary apoplexy (PA) is characterized by sudden increase in pituitary gland volume secondary to ischemia and/or necrosis. Certain predisposing factors can result in PA and use of gonadotropin-releasing hormone (GnRH) agonist for prostate cancer (PCa) is one such condition. We present a case of 59-year-old male who had insidious onset of PA following leuprolide administration, resulting in late presentation of PA. CASE PRESENTATION: A 59-years old male was referred to the endocrinology clinic for evaluation of pituitary enlargement found on MRI brain in June 2021. He complained of fatigue, anorexia, unintentional weight loss, diplopia, and blurry vision, which developed insidiously and gradually worsened over six months. In 2014, he was diagnosed with stage 4 PCa (Gleason Score=8) with metastasis to the lymph nodes, ribs, and pelvic bones and underwent palliative radiation for bone metastasis and androgen deprivation with intramuscular leuprolide 22.5 mg every 3 months between July 2014 till July 2020. On presentation, he was hemodynamically stable and visual field testing was negative. Anterior pituitary hormone evaluation revealed panhypopituitarism with low serum ACTH 5 pg/ml (7.2-63.3 pg/ml), cortisol 2.9 mcg/dl (5-15 mcg/dl), TSH 0.53 mclIU/ml (0.6-4.7 mclIU/ml), Free T4 0.27 ng/dl (0.58-1.76 ng/dl), IGF-1 58 ng/ml (54-258 ng/ml), LH 0.3 mIU/ml (1.5-9.3 mIU/ml), FSH 1 mIU/ml (1.4-18 mIU/ml) and testosterone < 3 ng/dl (1.5-9.3 ng/dl). Pituitary MRI July 2021 demonstrated subacute hemorrhage inside the pituitary gland which was not present in prior MRI in September 2020. Based on laboratory work up showing secondary adrenal insufficiency and central hypothyroidism, as well as pituitary imaging confirming apoplectic event, he was diagnosed with PA secondary to GnRH agonist use. He was initially treated with stress dose of steroids followed by prednisone 5 mg daily and levothyroxine 75 mcg daily. He had significant improvement of symptoms over next few weeks including near complete resolution of visual symptoms. CONCLUSION: Given high prevalence of PCa and increased use of GnRH agonists, more patients will develop PA, which was once thought to be extremely rare. Furthermore, it is critical that patients receiving GnRH agonists should be evaluated for possible PA, even in the absence of acute symptoms, which is classically seen in PA. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.