Management of the short stature due to pubertal delay in boys

Boys with constitutional pubertal delay who present with decreased growth rate pose diagnostic and therapeutic problems. Ninety-one boys seen after the age of 14 yr for height for age less than -2 SD, growth rate less than 5 cm/yr, and pubertal delay were evaluated. The GH peak after the arginine-insulin stimulation test was less than 10 micrograms/L in 35 of the subjects; these boys differed from the 56 others in having a GH peak of 10 micrograms/L or more, their higher body mass index (-0.27 +/- 0.2 vs. -0.85 +/- 0.1 score; P < 0.05), and lower plasma insulin-like growth factor-I (IGF-I; 1.2 +/- 0.2 vs. 1.8 +/- 0.2 U/mL; P < 0.05). The GH peak correlated negatively with the body mass index (P < 0.01), but not with plasma levels of testosterone and IGF-I or its GH-dependent binding protein (BP-3). At a second GH evaluation, performed with testosterone priming (21 boys; 100 mg testosterone heptylate/15 days, im; four doses) or without (6 boys), 23 patients had increased their GH peak to above 10 micrograms/L, and 4 had not. Three of these were treated with human (h) GH, and a third GH evaluation, performed after full pubertal development, showed a normal GH peak. The growth rate during the year preceding the GH evaluation was 3.8 +/- 0.1 cm (1-7 cm). During the year after the GH evaluation, it was 6.8 +/- 0.3 cm in the 32 patients followed without therapy, 7.3 +/- 0.3 cm in the 25 patients given testosterone (25 mg testosterone heptylate/15 days, im), and 7.3 +/- 1.4 cm in the 3 treated with hGH. Spontaneous growth during the 2 periods was correlated with testicular volume (P < 0.01) and the plasma testosterone level (P < 0.05), but not with the GH peak, plasma IGF-I, or BP-3. The final height (n = 49) was -1.0 +/- 0.1 SD, below target height (-0.4 +/- 0.1 SD; P < 0.0001). It was similar in patients with a GH peak below or equal to or above 10 micrograms/L and in those given or not given testosterone therapy. We conclude that the growth rate of boys with constitutional pubertal delay depends on the testicular volume and plasma testosterone level, but not on the GH peak, plasma IGF-I, or BP-3 levels. Final height is not altered by a transient drop in GH or by low dose testosterone therapy.