Objective: Provocative stimulation tests for GH assessment have poor reproducibility and can often elicit false positive results in normal children. The aim of our study was to evaluate the capability of pegvisomant, as an enhancer of GH secretion, in unmasking false-positive results in short children undergoing GH testing. Design: A prospective study was conducted between March 2005 and April 2006. Patients: Twenty-one short children (8 males and 13 females), aged 1.0-14.5 years, with a height of <2 SD scores below the mean were included in the study. Methods: All subjects underwent an l-DOPA stimulation test with evaluation of GH. At the end of the test, 1 mg/kg of pegvisomant was given subcutaneously and 3 days later an l-DOPA stimulation test was repeated. Results: There was a significant decrease of IGF-I SDS following pegvisomant (-1.75 ± 0.24 vs. -2.65 ± 0.23; P <0.0001) and a significant increase of the GH-peak (6.2 ± 0.91 vs. 15.3 ± 2.30 μg/l; P <0.0001). Among the 21 patients examined, 18 (85.7%) had an insufficient response (<10 μg/l) at the first stimulation. Ten of them (55.5%) showed normal secretion after priming with pegvisomant, while insufficient secretory reserve was confirmed in the remaining eight. Conclusions: Pegvisomant priming before GH stimulation tests can be used to improve the reliability of the diagnostic work up in GH deficiency. Further studies are required, however, to clarify whether this procedure should be recommended in the routine evaluation of GH status.
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