Growth hormone therapy for protein catabolism

GH and IGF-I have shown remarkable consistency of effect in a wide range ofcatabolic conditions. Doses of around 10 IU/m2/day of GH and 80micrograms/kg/day of IGF-I over short periods of time can improve netprotein synthesis and preserve lean body mass. Most studies have reportedmetabolic endpoints, but favorable clinical effects have included decreasedhospital stay and mortality in burns, improved respiratory muscle functionin COAD, preserved grip strength post- operatively, and improvements incardiac and bowel failure. Adverse effects of GH treatment are uncommon andusually related to glycaemic control. GH and IGF-I have differentialeffects on insulin concentrations--increasing or decreasing concentrations,respectively. The hypoglycaemic effects of IGF-I are dependent on route ofadministration and are avoided by subcutaneous delivery. Occasionalpatients have needed to discontinue GH treatment due to hyperglycaemia,although the anabolic action of GH may be partially mediated by increasedinsulin levels. The co-administration of GH and IGF-I has theoreticaladvantages by both increasing IGF binding-protein concentrations andbalancing glycaemic control. An initial study with combination therapy incalorically-restricted volunteers has shown anabolic effects greater thanwith either agent alone. This approach requires further study in catabolicpatients. There is a need for large, well-designed trials with clinicalrather than purely metabolic end-points, and some of these are alreadyunderway. Should these studies confirm the early findings, financialconsiderations will become paramount, although it remains possible thattreatment may be self-financing if lengths of hospital admissions areshortened.