Case Presentation: A 43-year-old woman presented to the emergency department (ED) with lightheadedness. Medical history was significant for triple-negative breast cancer treated with carboplatin, paclitaxel, and pembrolizumab eight months prior to admission. She underwent two cycles of chemotherapy before treatment was paused due to nausea, vomiting, and weight loss. She continued to have very poor appetite and had lost approximately 30 kg, prompting admissions at other hospitals for hypoglycemia and hypotension. In the ED, vitals were notable for temperature 36.7 ° C, heart rate 99 beats per minute, and blood pressure 89/60 mmHg. Laboratory data was notable for blood glucose 92 mg/dL, normal white blood cell count, normal complete metabolic panel, and lactic acid 1.4 mmol/L. Due to concern for sepsis, computed tomography of the chest, abdomen, and pelvis with IV contrast was obtained and showed no abnormalities. She received IV fluids with improvement in blood pressure and was admitted. While admitted, she had several episodes of nocturnal hypoglycemia which required administration of IV dextrose.Due to concern for adrenal insufficiency, serum cortisol was obtained at 08:00 AM and was undetectably low. Endocrinology was consulted and recommended starting IV hydrocortisone. The patient improved rapidly on IV hydrocortisone and was transitioned to oral hydrocortisone. Adrenocorticotropic hormone was undetectable. At a post-hospital visit with Endocrinology, hypoglycemia, hypotension, and fatigue had resolved. She had regained 20 kg of weight. Thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels were normal. She was diagnosed with autoimmune hypophysitis due to immune checkpoint inhibitor (ICI) therapy with pembrolizumab.
Discussion: An increasing number of patients are being treated with ICIs, antineoplastic agents that increase antitumor immunity by blocking intrinsic down-regulators of immunity. ICIs cause immune-related adverse events (irAEs) in up to 30-50% of patients (1). Although any organ system can be affected, irAEs commonly involve the gastrointestinal tract, endocrine glands, skin, and liver. Hypophysitis (inflammation of the pituitary gland) is characterized by symptoms of fatigue and headache. Diagnosis is established by low levels of hormones produced by the pituitary gland: ACTH, TSH, FSH, LH, growth hormone (GH), and prolactin. Long-term supplementation of affected hormones is necessary.
Conclusions: For patients with cancer who are admitted to the hospital, prompt review of cancer therapies may mitigate morbidity and mortality due to early diagnosis of irAEs for patients treated with ICIs.