HGH vs IGF 1 LR3: Scientific Comparison & Research Guide Insulin like growth factor 1 deficiency and metabolic syndrome Journal of Translational Medicine Springer Nature Link A Medical Review of IGF 1 LR3 Dosage, Side Effects and Safety Aspects IGF 1 LR3 does not promote growth in late gestation growth restricted fetal sheep American Journal of Physiology Endocrinology and Metabolism American Physiological Society Researchers can't fully explain why IGF LR3 outperforms its natural counterpart in preclinical models. Engineered in the 1990s with an arginine substitution and N terminal extension, this synthetic IGF 1 analog shows reduced IGFBP binding