SAT-061 Screening and Detection of Hypopituitarism in Patients Receiving CNS Radiotherapy - A Retrospective Audit

Abstract Disclosure: L. Batten: None. R. Akinyombojnr: None. S. Dixit: None. L. Baker: None. S. Mongolu: None. Introduction: Radiation treatment is used for patients with secreting and non-secreting pituitary adenomas, with residual pituitary adenomas, or recurrent pituitary adenomas to achieve long-term disease control. The side effects of radiotherapy may be acute toxicity (within weeks) and late toxicity occurring years after treatment. Pituitary hormone deficiencies are the most common late complication. Long-term endocrine evaluations are recommended in patients after cranial radiotherapy to identify new pituitary hormone deficiencies. The aim of this project was to determine whether patients who had not undergone a formal screening process exhibited undiagnosed, subclinical hypopituitarism. Methods: We collected data on all living patients with primary brain tumours who underwent brain radiotherapy between January 2018 and December 2022 at 2 sites within Hull University Teaching Hospitals (n=38). Patients were identified from multidisciplinary team meeting records. Patients with pituitary tumours were excluded, as they routinely receive endocrine follow-up.After applying exclusion criteria, 38 patients remained eligible for review. 9 patients were subsequently excluded from the final analysis: 4 were already receiving steroid replacement therapy, 2 were under active investigation by the endocrinology team, and 3 had undergone ad hoc screening tests. This resulted in a final cohort of 29 patients for data collection.Patients were contacted by telephone to obtain consent for blood sample collection. A common theme among patients was a lack of awareness regarding the potential of late complications from radiotherapy. Results:Baseline characteristicsAge33-79 years (median 51 years)Sex (male:female)16:13Radiotherapy dose54-60 GyRadiotherapy fractions28-33 fractions (median 30 fractions) CancerNumber Oligodendroglioma10 Astrocytoma8Meningioma7Ependymoma2Germinoma1Glioma1 Results from screeningTo date, data has been collected on 19 patients. 2 patients did not attend their scheduled screening blood test appointments. 9 patients exhibited suboptimal 9:00 AM cortisol levels (<320 mmol/L). Of these, 1 patient commenced palliative radiotherapy with dexamethasone supplementation, while the remaining 8 demonstrated adequate adrenal function during dynamic testing with an ACTH stimulation test.Additionally, 1 patient was found to have subclinical hypothyroidism. 1 patient was identified with secondary hypothyroidism. Conclusion: This analysis highlights the ad hoc nature of screening for late effects. Implementing an automated approach to identify and these patients for screening is essential.An important consideration is whether patients with a low 9:00 AM cortisol level should undergo insulin stress tests (IST) or glucagon stimulation tests. While these tests provide valuable diagnostic information, they are resource-intensive. Presentation: Saturday, July 12, 2025