Purpose: To evaluate the clinical, laboratory, radiological, therapeutic, and prognostic characteristics of patients with acromegaly according to the size of the growth hormone (GH)-secreting pituitary adenoma at diagnosis. Patients and Methods: Observational, retrospective, single-center study of patients with acromegaly followed at a tertiary center. Data from medical records were evaluated regarding age, symptoms, presence of arterial hypertension, type 2 diabetes mellitus, hypopituitarism, size of the initial lesion, invasiveness (cavernous sinus invasion), T2-weighted magnetic resonance imaging signal intensity, GH and insulin-like growth factor type 1 (IGF-1) levels, treatment performed [surgery, use of somatostatin receptor ligands (SRL), pegvisomant, cabergoline and bromocriptine and radiotherapy] and response to surgical or adjuvant treatment (normal levels of GH and/or IGF-1 after each treatment instituted).Patients were divided into groups according to the size of the adenoma at diagnosis (group I = smaller than 10 mm, II = 10-19 mm, III = 20-29 mm, IV = 30-39 mm and V = greater than 40 mm), and comparisons were made between the 5 groups and two-by-two comparisons. Results: 117 patients were studied (59 women, age at diagnosis 43 SD 13 years). Group I consisted of 11 patients (9%), group II of 54 (46%), group III of 34 (29%), group IV of 10 (9%) and group V of 8 patients (7%). The prevalence of hypertension, diabetes mellitus and hypopituitarism were 49%, 25% and 28%, respectively. Hypopituitarism, invasiveness, and the use of SRL had their prevalence increased according to the size of the adenoma, as well as GH levels. Age, on the other hand, showed a negative correlation with tumor size, and group I was older when compared to the group with macroadenoma. The ROC curves showed that in relation to the size of the adenoma at diagnosis, most of the outcomes evaluated (hypopituitarism, invasiveness, radiotherapy, use of SRL, use of medications other than SRL, disease control after surgery) occurred with a tumor diameter of around 20 mm. Conclusion: Our study demonstrated that microadenomas and macroadenomas smaller than 20 mm are associated with lower morbidity and better therapeutic response in acromegaly. From a tumor diameter of 20 mm, there was no significant difference in the clinical, therapeutic and prognostic behavior of GH-secreting pituitary adenomas.

The authors have declared no competing interest.

This study did not receive any funding

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Ethics committee/IRB of Federal University of Parana gave ethical approval for this work. Trial Registration number (Plataforma Brasil): CAAE 30066220.2.0000.0096.

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