FRI242 Primary And Secondary Adrenal Insufficiency Post Transsphenoidal Surgery In Patient On Abiraterone Therapy

Disclosure: R.O. Akande: None. J. Abramowitz: None. S. Mirfakhraee: None. Introduction: This case report describes the co-existence of primary and secondary adrenal insufficiency in a patient who received abiraterone therapy for metastatic prostate cancer and had transsphenoidal surgery for symptomatic pituitary adenoma. It sheds light on the presentation of the patient and explains the subsequent management. Clinical Case: A 67-year-old man with a history of metastatic prostate cancer (status post prostatectomy and radiation) and recent transsphenoidal surgery for pituitary adenoma presented with 3+ pedal edema. The patient had been discharged on hydrocortisone as per neurosurgery protocol and continued abiraterone after his transsphenoidal surgery. His pedal edema started two months after discharge. He denied fatigue, nausea, and dizziness. His vital signs and electrolytes, including serum potassium, were within normal limits. The patient was diagnosed with mineralocorticoid excess in the context of combined primary and secondary adrenal insufficiency. His hydrocortisone was changed to prednisone 5mg daily and his pedal edema subsequently resolved. Conclusion: Abiraterone, a hormonal therapy for the treatment of metastatic prostate cancer, is an irreversible inhibitor of CYP17, a microsomal enzyme with 17 alpha-hydroxylase and 17,20-lyase activities. This inhibition reduces cortisol and androgen concentrations while stimulating ACTH production. Thus, abiraterone use led to primary adrenal insufficiency in this patient. As a result of the 17 alpha-hydroxylase and 17,20-lyase pathway inhibition, there is increased production of deoxycorticosterone, which can lead to fluid retention. This patient was post pituitary surgery with partial secondary adrenal insufficiency and received hydrocortisone postoperatively as an appropriate glucocorticoid replacement in this setting. He developed pedal edema due to mineralocorticoid excess from abiraterone use while on hydrocortisone therapy. He was placed on prednisone, a more potent synthetic glucocorticoid than hydrocortisone, with subsequent rapid resolution of his edema. Presentation: Friday, June 16, 2023