Growth hormone receptor polymorphisms and growth hormone response to stimulation test: a pilot study

BACKGROUND: No gold standard pharmacological stimulation test exists for the diagnosis of growth hormone deficiency (GHD). In addition, the genetic factors that influence growth hormone (GH) responses remain unclear. This study aimed to determine whether polymorphisms in exon 6 of the GH receptor gene influence responses to the L-arginine GH stimulation test. METHODS: This study included 27 prepubertal patients with confirmed GHD. GHD was defined as a peak GH level <8 ng/mL in response to pharmacological stimulation. The mean GH peak after L-arginine stimulation was 2.9 +/- 2.9 ng/mL. RESULTS: The included patients had the following genotypes at the third position of codon 168: AA (N.=1), AG (N.=15) and GG (N.=11). Patients carrying the AA and AG genotypes exhibited stronger responses to arginine than patients with the GG genotype (3.1 +/- 2.7 vs. 1.5 +/- 1.3 ng/mL, P=0.01). CONCLUSIONS: The approach employed in this study could elucidate GH profiles under physiological and pathological conditions, facilitating improved interpretation of pharmacological stimulation tests.