MON-061 - Blind Spots in Survival: A Case of Panhypopituitarism Decades after Retinoblastoma Radiotherapy

Background: The pituitary gland is an important structure in the human body that secretes various hormones that are vital to normal body functions including growth, metabolism and reproduction. Panhypopituitarism is characterized by the deficiency of all the hormones produced by the anterior pituitary gland. Causes include congenital, inflammatory, granulomatous, neoplastic, traumatic, or irradiation involving the hypothalamic-pituitary axis. Diagnosis depends on the measurement of basal and stimulated secretion of pituitary hormones. It is a chronic, life-long condition requiring regular hormonal replacement and results in significant impairment in the patients quality of life and increased morbidity and mortality.

Case report: A 61-year-old male with history of retinoblastoma status post radiation therapy in childhood presented to the ED with hypotension, fatigue, nausea and vomiting, and was admitted for hyponatremia with further work up of hypotension. The patient was hospitalized for hyponatremia 2 years prior. Labs were significant for decreased levels in AM cortisol, ACTH, T4, FSH, LH, prolactin, and testosterone. The patient was diagnosed with adrenal insufficiency and was started on management with hydrocortisone, levothyroxine, and testosterone with endocrinology follow-up initiated.

Discussion: This case highlights the damaging effects of cranial irradiation and the complications that can arise if patients are not properly followed by a provider. According to Pekic, cranial irradiation also causes irreversible changes via direct hypothalamic neuronal and vascular injury leading to pituitary dysfunction (2024). One study measured hypothalamic volume in vivo and white matter lesions in cancer survivors after cranial radiation therapy. Retinoblastoma treatment delivers doses of 40-50 Gray (Gy) of radiation, however a dose of 10 Gy is sufficient to cause growth hormone disruption. ACTH deficiency usually occurs with a radiation dose of 30Gy to the HPA, leading to symptoms of hypotension, hypoglycemia, and worsening clinical status in those that are critically ill (Tonorezos 2015).

Conclusion: Radiation therapy to the head puts patients at risk for multiple endocrine abnormalities due the damage it inflicts to the hypothalamic-pituitary axis. Damage to the pituitary gland can be slowly progressive and take years to emerge. Thus, it is critical for cranial radiation recipients to be followed by an endocrinologist for monitoring and replacement of hormone deficiencies.

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