Endocrine Abstracts

The impact of GH/IGF-1 levels on skeletal muscle in patients with acromegaly is still matter of debate. Recently, temporal (TMT) and masseter muscle thickness (MMT) have emerged as reliable indicators of muscle mass, as well as patients’ functional status/prognosis in various clinical context – especially in the oncologic setting. This study aims to investigate the potential correlations between TMT/MMT and patients’ demographic and clinical characteristics. A retrospective longitudinal analysis was conducted at a single tertiary center for pituitary diseases. Sixty-nine patients diagnosed with acromegaly, each with at least one brain/sella turcica MRI scan and matched clinical data, were included. The primary outcomes assessed were TMT, MMT, and muscle fatty infiltration (evaluated using the modified Goutailler score) at baseline (69 MRIs) and over time (total of 182 MRIs). The median time between first to last available MRI was 49 months. Results revealed that, at baseline, males had significantly higher TMT and MMT compared to females (P=0.001 and P=0.016, respectively). A direct association between TMT and MMT was observed (β 0.508, P<0.001). TMT was positively correlated with IGF-1 ×ULN (P=0.047), while MMT showed positive correlations with IGF-1 ×ULN (P=0.001), patient weight (P=0.015), and height (P=0.006). The presence of hypogonadism or impaired glucose metabolism did not significantly correlate with TMT or MMT. No significant difference in TMT and MMT has been observed when comparing patients with active cancers, with cancers in remission, and those with a negative clinical history for malignancies. Considering all available MRIs, sex and IGF-1 ×ULN emerged as significant determinants of both TMT and MMT in multivariable analysis (female sex: β -0.345/-0.426, P<0.001; IGF-1 ×ULN: β 0.257/0.328, P<0.001). Patients defined at risk of sarcopenia - by sex-specific TMT cut-offs – had IGF-1 ×ULN levels significantly lower compared to individuals classified as having normal muscle status (P=0.016). At longitudinal evaluation, patients with uncontrolled acromegaly at baseline exhibited a significant reduction in MMT over time (P=0.044). Notably, considerable fatty infiltration was observed in 34-37% of MRIs, with age identified as the main determinant (temporal muscle: OR 1.665; P=0.013; masseter: OR 1.793; P=0.009). In conclusion, male patients with higher IGF-1 values demonstrated thicker temporal and masseter muscles, indicative of greater muscle mass compared to other patients.