Grоwth Hоrmоne Deficiency & Growth Hormone Receptor Disorders (Study Outline) For study only—this is not medicаl аdvice or а substitute for professional care. 1. Background Definition:Conditions characterized by impaired growth due to inadequate GH secretion (pituitary origin) or impaired GH action (receptor or post-receptor defects). GH Deficiency: Low GH production. GH Resistance (Receptor Disorders): Normal or elevated GH, but defective GH receptor → low IGF-1. Classic example: Laron syndrome (autosomal recessive GH receptor mutation). Pathophysiology: GH normally stimulates hepatic IGF-1 production, promoting bone growth and protein synthesis. Deficiency: ↓ GH → ↓ IGF-1 → reduced linear growth. Resistance: GH present but ineffective → very low IGF-1, elevated GH due to loss of feedback. Etiology: GH Deficiency (GHD): Congenital: pituitary aplasia, midline defects, genetic defects (PROP1, PIT1). Acquired: trauma, CNS tumors (craniopharyngioma), radiation, infections, autoimmune hypophysitis. GH Resistance: GH receptor mutations (Laron syndrome). Post-receptor signaling defects. Liver disease (impaired IGF-1 synthesis). Epidemiology: Presents in childhood with poor linear growth; can also occur in adults with pituitary disease. 2. History Children: Short stature (height