VARIABILITY OF SERUM HUMAN GROWTH-HORMONE LEVELS IN DIFFERENT COMMERCIAL ASSAYS - SPECIFICITY OF GROWTH HORMONE-RELEASING HORMONE STIMULATION

Serum human growth hormone (hGH) levels were measured with three diffe rent commercial kits, comprising a radioimmunoassay (RIA) (bioMerieux, Marcy-l'Etoile, France,'bmpoly') and two immunoradiometric assays (IR MA) (bioMCrieux, 'bmmono', and CIS bioInternational, Gif-sur-Yvette, F rance, 'cismono'). Samples were collected after various stimulation te sts [arginine-insulin, growth hormone-releasing hormone (GHRH), L-dopa and glucagon-beta-axolol] from children who were undergoing evaluatio n for short stature. Values obtained with the IRMAs were consistently lower than those obtained with the RIA. Furthermore, the cismono/bmmon o and cismono/bmpoly values ratios were always significantly higher wh en samples were collected during GHRH stimulation than during the othe r stimulation tests. These data indicate that GHRH could induce a part icular form of hGH molecule (in nature or in amount), recognized by th e monoclonal antibodies in the cismono kit and that a specific form of hGH may be released by GHRH stimulation.