Correlation between pituitary growth hormone reserve and degree of growth failure in children with short stature

Abstract

The correlation between a releasable pituitary growth hormone (GH) pool and degree of growth failure was examined in 30 children with GH deficiency (group I) and 19 children with normal short stature (group II). Based on the responsiveness of GH to GH-releasing hormone (GHRH), group I, with low GH responses (below 7 ng/ml) to both insulin and arginine, was classified into three subgroups; I_a (peak value less than 10 ng/ml, n=19), I_b (10–20 ng/ml, n=5) and I_c (above 20 ng/ml, n=6). Group II, with a GH response above 10 ng/ml to either insulin or arginine, was also divided into II_a (below 20 ng/ml, n=5) and II_b (above 20 ng/ml, n=14). Body length and growth velocity in I_a and I_b were significantly reduced vs I_c; bone age in I_a was retarded vs I_c; plasma somatomedin C (Sm-C) levels in I_a and I_b were decreased vs I_c, who had almost normal levels (0.90±0.55 U/ml). The incidence of other combined pituitary hormone deficiencies and previous perinatal distress was definitely high in I_a and I_b, but zero in I_c. In group II also, body length and growth velocity were significantly decreased in II_a vs II_b (P<0.01). These results indicate that [1] the pituitary reserve of GH estimated by GHRH is a good reflection of the degree of growth failure in GH-deficient children as well as in those of normal short stature, [2] hypothalamic GHRH deficiency tends to have a milder effect on growth retardation than pituitary GH deficiency, and [3] normal short children with a diminished GH reserve may be potential candidates for the GH treatment.