LBODP073 Non-functioning Pituitary Macroadenoma Presenting As Osteopenia In A Male

Non-functioning pituitary macroadenomas (NFPAs) account for 14-54% of all pituitary adenomas. NFPAs are benign, but mass effects may lead to significant symptoms, including visual impairment and pituitary insufficiency, of which secondary hypogonadism is present in 75% of reported cases. Patients with hypogonadism may experience decreased bone density, libido, muscle mass/strength, and fatigue. We describe a patient who presented with osteopenia, in addition to atypical symptoms of secondary hypogonadism, associated with low testosterone levels. Further workup disclosed a large pituitary macroadenoma. A 56-year-old male presented to the clinic for a two-year history of diffuse joint pain. X-rays were significant for bone loss. This led to a bone density scan that showed osteopenia with a T score of -2.3 in the lumbar spine and left femoral neck. He had no prior history of fractures or loss in height. Risk factors for bone disease were only pertinent for history of osteoporosis in his mother. He was referred to endocrinology for further evaluation. Work up included normal vitamin D levels, 24-hour urine calcium excretion, morning cortisol, and TSH. Given the patient's osteopenia and additional complaints of decreased appetite, weight loss, fatigue, and muscle weakness, testosterone levels were checked and found to be low. Free testosterone level was 14.3 pg/ml with inappropriately low FSH and LH. Prolactin was normal at 12.5 ng/ml. He subsequently had an MRI brain which revealed a pituitary macroadenoma measuring 2. 0×2.4×2.4 cm with mass effect on the optic chiasm. However, the patient did not complain of headaches or visual disturbances and visual field testing was normal. He underwent transsphenoidal resection of the pituitary tumor which led to normalization of testosterone levels and resolution of all his symptoms. This case exemplifies how non-specific symptoms of hypogonadism and absence of mass effect symptoms can lead to a delay in diagnosis of NFPA. Typically, NFPAs are detected when they are large enough to cause symptoms of mass effect which, interestingly, were absent in this patient despite compression of the optic chiasm. Male hypogonadism increases the risk for bone disease. Thus, it is important to pursue work up for secondary hypogonadism in males presenting with osteopenia/osteoporosis despite lack of overt symptoms. A thorough history and workup are essential in diagnosing NFPA. Prompt detection of NFPA can facilitate timely management leading to clinical improvement. The first line of treatment for NFPAs causing neurological symptoms is transsphenoidal surgical resection. Surgery is also recommended for NFPAs that are at high risk for causing visual deficits due to involvement of optic chiasm, as was seen in this patient. Post-surgical follow up includes long-term routine monitoring of hormone levels and neuroimaging. Presentation: No date and time listed