Abstract: A method and apparatus for therapeutically effective treatment of a living animal comprising administering a dynamic dosage of growth hormone releasing factor or analog thereof, or administering growth hormone or analogs thereof in a chronic course of treatment in a subdesensitizing regimen. Also a method of diagnosing living animals with an anterior pituitary unresponsive to growth hormone releasing factor or analogs thereof. A method of determining the optimum GRF and GH dynamic dosage for a given living animal, particularly a human.