6367 Growth gone Awry: A Rare Case of Acromegaly in a 16-Year-Old Female with Panhypopituitarism Secondary to Craniopharyngioma on Low Doses of Growth Hormone with Low IGF-1 levels

Abstract Disclosure: L.M. Ayala Castro: None. J. Ye Tay: None. A. Diaz: None. This report highlights a rare case of a 16-year-old female with panhypopituitarism due to craniopharyngioma, where GH replacement therapy triggered acromegaly features despite having low IGF-1 levels. Background: Craniopharyngiomas are the most common tumors causing acquired pituitary deficiencies in children. Various mechanisms contribute to acromegaly, and hypersensitivity to hormonal treatment in this benign tumor emerges as a plausible avenue for investigation. Case Presentation: A 16-year-old female diagnosed with craniopharyngioma at age 5 developed secondary panhypopituitarism. Baseline hormonal profiles indicated markedly reduced levels of IGF-1 and insulin growth factor–binding protein 3 (IGF-BP3). Despite the established condition, GH treatment was initiated at age 8 for potential growth and development benefits. Before commencing GH therapy, a bone age assessment revealed normal skeletal development. However, GH replacement therapy led to an unexpectedly robust response, resulting in physical changes consistent with acromegaly. Paradoxically, laboratory evaluations showed low IGF-1 levels. Imaging studies, including pituitary MRI, ruled out new abnormalities or tumors. As the patient approached peak adult height at 16, having been on adult GH therapy since age 13, a decision was made to discontinue GH replacement therapy and address acromegaly symptoms. Frequent follow-up visits were planned to assess growth velocity, monitor hormonal levels, and evaluate potential adverse effects. Discussion: This case demonstrates an unusual sensitivity to exogenous GH, resulting in an exaggerated response contrary to expected IGF-1 elevation. Atypical IGF-1 levels may suggest alterations in liver physiology, GH receptor signaling pathways (e.g., Laron Syndrome), or downstream defects in IGF-1 synthesis. Further research is crucial to elucidate the underlying mechanisms. Conclusion: Only 3 cases of acromegaly as a side effect of GH replacement therapy have been reported in the literature. We report a further case that underscores the complexity of managing hormonal imbalances, especially in unique patient populations with panhypopituitarism secondary to craniopharyngioma. The unexpected response to GH treatment emphasizes the need for individualized approaches and vigilant monitoring. References: Beate Karges, Roland Pfäffle, Bernhard O. Boehm, Wolfram Karges; Acromegaly Induced by Growth Hormone Replacement Therapy. Hormone Research 1 March 2004; 61 (4): 165–169. https://doi.org/10.1159/000076007 Tuthill A, McKenna TJ, O’Shea D. Iatrogenic acromegaly. Endocrine Abstracts. 2002;3:P35. Eiriny T. Eskander, Vivien Bonert, Acromegaly as a Complication of Growth Hormone Therapy, AACE Clinical Case Reports, Volume 1, Issue 1, 2015, Pages e68-e72, ISSN 2376-0605, https://doi.org/10.4158/EP14165.CR. Presentation: 6/3/2024