MON-072 Probability of early diagnosis of autonomous growth hormone secretion in patients with hyperprolactinemia

Abstract Disclosure: M. Otsuki: None. Y. Yoshida: None. K. Amano: None. T. Kawamata: None. N. Hizuka: None. Introduction: The effects of growth hormone (GH) hypersecretion on acral and soft tissue growth and metabolic function occur insidiously over several years. As a result, the diagnosis of acromegaly is often delayed. Early diagnosis of acromegaly is essential to minimize acral and soft tissue growth and metabolic dysfunction. We present two cases where autonomous GH secretion was diagnosed early. Case 1: A-41-year-old woman was referred to our hospital for evaluation of amenorrhea, hyperprolactinemia (262 ng/mL) and a pituitary macroadenoma. Her hormonal examination showed lower estradiol levels due to hyperprolactinemia, normal GH levels, and slightly higher insulin-like growth factor-1 (IGF-1) levels (265 ng/mL [41-year-old:95-240]). GH levels were not suppressed by a 75-g oral glucose tolerance test (OGTT) and showed a paradoxical response to thyrotropin releasing hormone (TRH) test. She was diagnosed with a GH-prolactin (PRL) producing adenoma and underwent transsphenoidal surgery, even though she had no typical clinical features of acromegaly. An immunohistochemical examination showed diffuse positive staining of PIT-1 and PRL and local positive staining of GH and follicle-stimulating hormone. Case 2: A-25-year-old woman was referred to our hospital for evaluation of amenorrhea, hyperprolactinemia (113.9 ng/mL) and a pituitary microadenoma. Her hormonal examination showed lower estradiol levels due to hyperprolactinemia, normal GH levels, and mild higher IGF-1 levels (400 ng/mL [25-year-old:147-358]). GH levels were not suppressed by a 75-g OGTT and paradoxical response to TRH test. She was diagnosed with a GH-PRL producing adenoma and underwent transsphenoidal surgery, even though she had no typical clinical features of acromegaly, similar to Case 1. An immunohistochemical examination showed positive staining of PIT-1, PRL, and GH in the same tumor cells. Conclusion: Estrogen blunt IGF-1 production through phospholipase C and suppressors of cytokine signaling 2 inductions. Based on the two cases described above, the decrease in estrogen levels due to hyperprolactinemia induces a slight or mild elevation of IGF-1 and may provide an opportunity for the early diagnosis of GH-PRL producing adenomas. Presentation: Monday, July 14, 2025