Abstract 2

We determine the levels of growth hormone binding protein (GHBP) in puberal children with GHD, before and after treatment with rhGH at a dose of 0.1 U/Kg/day during one year. We studied 9 patients (5 boys and 4 girls) in early puberty (Tanner II or III) whose mean age was 13.7 ± 0.7 years bone age 11.1 ± 0.1 years, height < -2.4 SDS and growth velocity < 5.4 cm/year at study entry. The diagnosis of GHD was based upon a peak response to two GH stimulation tests (Insulin and clonidine) < 7.0 ng/ml. GHBP was determined by RIA using a monoclonal antibody (Mab 263). The results are expressed as % of adult normal serum (% RSB) Table

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We found a negative correlation between GHBP and growth velocity before as well as after GH treatment (r=-0,73 and r=-0,80 respectively p<0.02). However 7 of the 9 patients studied showed a decrease in their GHBP levels, whereas 2 patients showed an increase of GHBP concentrations after treatment, suggesting a non consistent effect of GH on GHBP. We conclude that an inverse relationship appears to exist between GH and GHBP circulating levels in GHD children. Therefore, the increased growth velocity and IGF-I levels induced by GH treatment appear not to be associated with an increment in the circulating levels of the extracellular domain of the GH receptor.