12373 A Long-term Follow Up Of Subclinical Acromegaly: A Case Series

Abstract Disclosure: H.M. Babu: None. I. Ebrahim: None. N.O. Vietor: None. T.D. Hoang: None. M.K. Shakir: None. Acromegaly usually presents with classic clinical features such as acral enlargement, facial features, headaches, fatigue, hyperhidrosis, snoring and oily skin. However, cases with atypical clinical features have been reported on silent GH-secreting pituitary tumors. The term ‘subclinical acromegaly’ is used to describe patients with GH hypersecretion without clinical features. We are reporting the long-term follow up of 2 patients with silent acromegaly. Case 1: A 40-year-old Caucasian female was seen 6 years ago with symptoms of arthralgias, cognitive slowing, headaches, and depression. Physical examination was completely normal without evidence to suggest acromegaly. While she was undergoing evaluation for multiple sclerosis, a brain MRI revealed a cystic lesion measuring 1.6 x 0.9 cm. An insulin like growth factor- 1 (IGF-1) level was incidentally screened and was elevated at 823 ng/mL (ref 69-227) and a glucose tolerance test (GTT) reported a growth hormone (GH) level of 7.5 ng/mL at its nadir. The patient underwent transsphenoidal surgery and histology of the resected tumor confirmed a somatotroph tumor. Following surgery, IGF-1 level remained mildly elevated (321 ng/mL) and patient has continued to have arthralgias and diaphoresis. She was treated with lanreotide injection which improved her symptoms. A recent MRI revealed no evidence of residual or recurrent tumor along with normal IGF-1 levels. Case 2: A 78-year-old female was admitted to the hospital 9 years ago with bipolar disorder. An MRI of the brain revealed a left pituitary macroadenoma of 1.5 cm. Patient had no clinical features of acromegaly and laboratory studies revealed an IGF-1 level of 768 ng/mL along with a GH level of 8.9 ng/mL at its nadir during a GTT. Serum prolactin level, thyroid functions and adrenal functions were normal. However, patient also had laboratory values consistent with primary hyperparathyroidism. A genetic screen for MEN-I was negative. Although patient agreed to undergo parathyroid surgery, she did not consent for pituitary surgery. Following parathyroid surgery patient remained eucalcemic. Patient was started on octreotide LAR 30 mg every month and she tolerated the treatment well. She did not manifest any acromegalic features during the 9 years of follow up. A recent IGF-1 level was 161 ng/mL and an MRI showed a stable pituitary adenoma (1.6 cm). In conclusion, the diagnosis of acromegaly may be delayed in patients with subclinical acromegaly. Often an incidental finding of a of a pituitary lesion along with an elevated serum IGF-1 level will lead to a diagnosis of subclinical acromegaly. Although pituitary surgery is the preferred choice in these patients, somatostatin analogue treatment may also be effective in selected patients. Finally, our first case emphasizes the importance of a detailed hormonal evaluation in patients who present with cystic pituitary incidentalomas. Presentation: 6/1/2024