IGF1 and acromegaly: Bone dimensions are increased in active acromegaly, primarily due to enhanced periosteal apposition, theoretically leading to a decreased fracture risk.(1, 2) Growth hormone (GH) exerts direct effects through interaction with the GH receptor in target tissues and indirectly mediated via insulin‐like growth factor 1 (IGF‐1) produced by the regulation of GH, mainly in the liver (the somatomedin hypothesis),(3) but also in peripheral target tissues including bone.(4, 5) In active acromegaly, nonphysiological levels of GH and IGF‐1 have a major impact on bone homeostasis.