Auxin can be used to treat developmental retardation caused by growth hormone deficiency.  

Growth hormone, also known as human growth hormone (hgh), is a peptide hormone that is banned for use in sports and is commonly used to treat dwarfism.  It has synthetic and metabolic effects that increase muscle mass, promote bone growth in children and adolescents, and strengthen tendons and internal organs.  Athletes use GH illegally mainly to build muscle and strength to gain a competitive advantage.  

According to the literature, subcutaneous or intramuscular injection is equally effective, and subcutaneous injection usually brings higher serum GH concentrations than intramuscular injection, but the IGF-1 concentration is the same.  GH absorption is usually slow, with plasma GH concentrations usually peaking 3-5 h after administration, with a typical half-life of 2-3 h.  GH is cleared through the liver and kidney, faster in adults than in children, and the direct elimination of unmetabolized GH in the urine is minimal.  Indications: To treat slow growth and severe burns in children with endogenous growth hormone deficiency, chronic renal failure, and Turner syndrome.  

Why human growth hormone production decreases with age:  

Self-feedback loops in action.  When IGF-l decreases in the body, signals are sent to the pituitary gland to secrete more hGH, and this autogenous feedback loop function decreases with age.