Peak serum GH concentrations with arginine/GHRH

GH concentrations in patients with MPHD and in age and gender-matched control subjects following the administration of a combination of arginine and GHRH. The median peak GH level in each group is denoted with a horizontal bar. The dashed lines and superscripts indicate diagnostic cut-points as follows: using (a) a maximum response of 4.1 ng/mL, the combination of specificity (91 percent) and sensitivity (95 percent) is maximized, whereas using (b) a maximum response of 4.6 ng/mL or (c) a minimum response of 1.5 ng/mL, sensitivity and specificity are 95 percent, respectively. The inset illustrates the time course of the mean serum GH concentration in response to the stimuli in the two groups of subjects.