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 different commercial kits, comprising a radioimmunoassay (RIA) (bioMerieux, Marcy-l'Etoile, France,'bmpoly') and two immunoradiometric assays (IRMA) (bioMCrieux, 'bmmono', and CIS bioInternational, Gif-sur-Yvette, France, 'cismono'). Samples were collected after various stimulation tests [arginine-insulin, growth hormone-releasing hormone (GHRH), L-dopa and glucagon-beta-axolol] from children who were undergoing evaluation for short stature. Values obtained with the IRMAs were consistently lower than those obtained with the RIA. Furthermore, the cismono/bmmono and cismono/bmpoly values ratios were always significantly higher when samples were collected during GHRH stimulation than during the other stimulation tests. These data indicate that GHRH could induce a particular form of hGH molecule (in nature or in amount), recognized by the monoclonal antibodies in the cismono kit and that a specific form of hGH may be released by GHRH stimulation.