Objective: To determine whether urinary growth hormone (U-GH) measurement is a useful indicator of subsequent growth rate in young boys.
Methods: We assessed the U-GH concentrations in five early pubertal boys with constitutional short stature (CSS) who were referred to a growth clinic and compared the results with those obtained in normal children and in children with GH deficiency.
Results: In the five early pubertal short-stature boys, the U-GH concentration ranged from 3.7 to 9.7 ng/night and, despite their blunted plasma GH responses to two different pharmacologic tests (peak plasma GH <7 ng/mL), proved to be a useful indicator of their subsequent normal growth rate. The U-GH was 2.2 +/- 0.2 and 4.1 +/- 0.5 ng/night in 38 normal prepubertal and pubertal children, respectively, 2.4 +/- 0.2 ng/night in 13 subjects with CSS, and 1.1 +/- 0.2 ng/night in 16 GH-deficient short-stature children.
Conclusion: We may speculate that 24-hour GH secretion and possibly U-GH normalize sooner than do responses to provocative testing as sex steroids appear in early pubertal constitutional short-stature boys. From a practical standpoint, it seems that U-GH values higher than 2.6 ng/night (mean + SE value for subjects with CSS) in such patients may justify postponement of the pharmacologic tests and waiting for growth during the subsequent year.