THE EFFECT OF LUTEINIZING-HORMONE-RELEASING HORMONE ANALOG FOR CENTRAL PRECOCIOUS PUBERTY ON GROWTH-HORMONE (GH) AND GH-BINDING PROTEIN

The pubertal growth spurt is characterized by a marked increase in the amplitude of GH secretory pulses. The high affinity GH-binding protein (GHBP) reportedly has an important role in enhancing the growth-promoting action of GH, Levels of GHBP are characteristic for an individual and increase only slightly as puberty progresses. It has been hypothesized that each individual adjusts GH production to a level appropriate for his GHBP environment. The withdrawal of gonadal steroids that occurs in children with central precocious puberty (CPP) treated with LH-releasing hormone agonist (LHRHa) therapy results in a decrease in growth velocity (GV) and GH secretion. This study was performed to determine the effect of treatment of CPP with the LHRHa leuprolide acetate for depot suspension on CH secretion and levels of GHBP. Six girls and one boy with CPP were studied before and 6 months after treatment was initiated. Within 6 months of initiation of therapy, there was a significant decline in GV, from 8.9 +/- 3.2 to 5.4 +/- 2.0 cm/yr (P < 0.05). Twelve-hour mean nocturnal GH levels decreased significantly from 8.6 +/- 3.5 to 5.1 +/- 2.3 mu g/L (P < 0.05). This occurred via a decrease in the amplitude of GH pulses as the number of peaks remained 4.6 and 4.1/12 h. Individual levels of GHBP were variable and reflect the wide range of levels observed in normal children. Although GV and GH levels decreased substantially, mean GHBP levels remained unchanged at 139.9 +/- 46.0 and 152 +/- 39.8 pmol/L. In children with CPP, within 6 months of LHRHa therapy, the decrease in GV occurs via a decrease in nocturnal GH secretion as levels of GHBP remain unchanged. In children with CPP, the withdrawal of gonadal steroids may inhibit the child's ability to secrete the GH appropriate for his/her GH/GHBP milieu.