PRETREATMENT WITH SMS 201–995 POTENTIATES GRF RESPONSE IN SHORT CHILDREN

Abstract

We tested the hypothesis that prior inhibition of spontaneous GH secretion by administration of the somatostatin analog SMS 201-995 (SMS) will enhance the GH response to a subsequent GRF challenge. Two controlled protocols were employed in 37 short children [M=31, F=6, aged 11.8 ± 1.6 yr (M ± SEM), height SDS −2.25 ± 0.55]. Study I determined an optimal regimen: SMS (0.8-2.2 ug/kg, sc) was randomly administered or not at 08:00 h and a GRF bolus (50 ug, iv) was given 4 h later. Study 2 used standard doses of SMS (1 ug/kg, sc) and GRF (1 ug/kg, iv), and a 1 h delay of the GRF injection. GH levels were measured q 20 min until 2 h following the GRF and expressed as the GH area under the curve during the 4-5 h SMS-GRF interval (AUC 1, ug/L/h) and as GH response to GRF for 2 h following GRF (AUC 2, ug/L/h; GH peak, ug/L).In study 1, SMS significantly suppressed spontaneous GH secretion and GH response to GRF, compared to control. In study 2, GH secretion was still suppressed during the 5-h SMS-GRF interval, but both the GH area and peak GH response to GRF were significantly increased by pretreatment with SMS. Thus, a “priming” SMS dose of 1 ug/kg significantly augmented the GH response to GRF given 5 h later, enhancing the diagnostic value of the 'standard” GRF test.