IGF1 and acromegaly: GH over-secretion leads to increased serum insulin-like growth factor 1 (IGF-1), and both hormones result in a series of acromegaly-associated symptoms, i.e., facial appearance changes; overgrowth of hands and feet; headache; visual field defects; and comorbidities affecting the cardiovascular system, respiratory system, musculoskeletal organs, endocrine/metabolic system, etc (3–7).