When Your Pituitary Fails - A Rare Case of Pituitary Dysfunction Due to Nivolumab and Ipilimumab

Immunomodulators like Nivolumab and Ipilimumab are important regimens in many malignancies. However, their use is linked with the rare side effect of pituitary dysfunction that if screened and treated can prevent misdiagnosis. Case Description: A 56-year-old male with a history of renal cell carcinoma status post bilateral partial nephrectomy with metastasis to the lung on Nivolumab/Ipilimumab presented with dizziness. He endorsed difficulty with balance, nausea, decreased appetite, feeling dehydrated and recent blood pressure readings in the 90s. Vitals on presentation were stable. An MRI, from 2 weeks ago, showed a slightly enlarged sella but no metastatic disease. The next day, he became hypotensive with minimal response to fluids and was started on Midodrine. However, considering his persistent hypotension, his cortisol level was checked and found to be profoundly low (<1). Literature review of his immunomodulator revealed the possibility of central adrenal insufficiency. In addition, he was noted to have a low TSH (0.02) with normal FT4 (1.08). Subsequently, his ACTH level was also found to be low (<1.5) which further elucidated a central cause for his adrenal insufficiency. Therefore, he was ultimately treated with PO hydrocortisone with plans to taper off in the next few weeks. Conclusion: This case demonstrates a rare yet significant side effect of Nivolumab/Ipilimumab therapy. Timely diagnosis and therapy can alleviate symptoms due to associated hormonal deficiencies. Moving forward it will be interesting to see if starting prophylactic steroids or routine screening will allow us to diagnose pituitary dysfunction due to Nivolumab/Ipilimumab earlier.