Loss-of-function mutation of STAT3 can induce hyperimmunoglobulin G syndrome, which is characterized by symptoms of osteoporosis, recurrent minimal bone fracture and skeletal morphological defects.36 Osteoblast/osteocyte-specific STAT3-knockout mice exhibit significantly lower bone mass due to reduced bone formation and enhanced bone resorption.37 However, whether STAT3 is responsible for the anabolic effect of iPTH remains unknown. Here, STAT3 is linked to osteoporosis.