In people with acromegaly (a condition with too much growth hormone and IGF‑1), more than half also have anemia. Most of the anemia is mild and not caused by iron, B12, or folate deficiencies. Higher IGF‑1 levels, larger invasive tumors, and certain treatments (like somatostatin drugs) were linked to a greater chance of being anemic.

Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) influence erythropoiesis; however, data on the prevalence and determinants of anemia in acromegaly are limited. This study aimed to investigate the frequency, characteristics, and risk factors of anemia in patients with acromegaly. We retrospectively reviewed medical records of 381 patients with acromegaly followed at a tertiary referral center. Clinical, hormonal, radiological, and hematological data were analyzed. Anemia was identified in 219 of 381 patients with acromegaly (57.5%). Most cases were normocytic (67%) and of mild severity (45%), while moderate and severe anemia accounted for 11.3% and 0.8%, respectively. Iron deficiency anemia was present in 41 of 219 anemic patients (18.7%) more frequently in women than men (27/120 [22.5%] vs. 14/98 [14.3%]), and thalassemia minor was detected in 4% of cases. No folate- or vitamin B12-deficiency anemia was observed. The majority of anemic cases (77.3%) remained unexplained. Sex-specific analyses showed that microcytic anemia was predominantly seen in women (49/73, 67.1%), whereas normocytic anemia displayed a nearly equal distribution between men (74/145, 51.0%) and women (71/145, 49.0%). Compared with non-anemic patients, those with anemia more frequently had macroadenomas with invasive features, residual tumor on postoperative imaging, and hypopituitarism, together with higher postoperative GH, IGF-1, and prolactin levels (all p < 0.05). They required more intensive treatment, including somatostatin receptor ligands (SRLs) (71.1% vs. 49.7%), dopamine agonists (18.8% vs. 10.4%), and radiotherapy (29.8% vs. 9.2%). Cancer prevalence was also higher in anemic patients (17% vs. 10.4%), although not statistically significant. Multivariate analysis identified macroadenoma, SRL therapy, and L-thyroxine use as independent predictors of anemia. Anemia is a frequent and clinically relevant comorbidity in acromegaly, associated with tumor burden, hypopituitarism, treatment intensity. These findings highlight the need for systematic evaluation of anemia in acromegalic patients and underscore the importance of future prospective studies to clarify its complex pathophysiology.