Decreased growth hormone response to growth hormone-releasing hormone in Turner's syndrome: Relation to body weight and adiposity

Abstract

Abstract. A decreased growth hormone response to various secretagogues has been described in Turner's syndrome, but the mechanisms responsible for this decrease are unknown. Seventeen prepubertal girls with Turner's syndrome (age 6.4 to 15.7 years; height −0.2 to −5.4 sd, bone age −3.7 to −0.3 sd; weight 93 to 169% of ideal body weight) underwent a stimulation test with GHRH (0.5 μg/kg). Plasma GH and prolactin were measured by radioimmunoassay from −30 to +120 min and insulin-like growth factor-I at time 0. These values were compared with those observed in lean children with constitutional short stature. Peak plasma GH after GHRH was 17.0±3.6 μg/l (mean±sem), significantly lower (p<0.001) than in the short lean children (39.2±5.1 μg/l. In Turner's syndrome patients, the peak GH value was negatively correlated with the percentage of ideal body weight (r=−0.58, p<0.02) and of body fat (r=−0.59, p<0.02). Plasma prolactin levels in Turner's syndrome did not rise after GHRH and showed a normal circadian variation, from 8.0±1.0 μg/l at 08.30 h to 5.0±0.7 μg/l at 11.00 h (mean ±sem). Mean (±sem) baseline plasma insulin-like growth factor-I concentrations was 0.88±0.14 kU/l, higher than in the short lean children (0.49±0.08 kU/l, p<0.05). We conclude that the decreased GH response to GHRH of girls with Turner's syndrome is related, at least in part, to their excess body weight and fat and is associated with higher IGF-I levels than in short lean children.

The Somatotropin-Somatomedin Axis in Adult Patients with Turner Syndrome: Measurement of Stimulated GH, GH-BP, IGF-I, IGF-II and IGFBP-3 in 25 Patients

“…GH secretion is suppressed in overweight sub jects [11. 24], A similar relationship has been previously reported for patients with Turner syndrome [8,10]. In view of the elevated BM1 in our patient group and the identical GH release upon arginine stimulation compared with control women.…”

“…GH sufficiency is further supported by the finding of normal or even elevated levels of IGF-I in Turner patients [8][9][10], In our study. IGF-I was slightly but not signifi cantly higher in the Turner group.…”

“…6]. Serum levels of IGF-1 have been reported to be normal, elevated or suppressed [7][8][9][10]. While most of these studies have been performed in pediatric patients with the syndrome, no data are available on the GHsomatomedin axis in adult patients with Turner syn drome.…”

Response to three years of growth hormone therapy in girls with Turner syndrome

“…The etiology of growth failure in TS is not well understood. Some studies19-21) reported that GH secretion decreased in subjects with TS whereas normal GH secretion was observed by other authors22,23). It is not clear whether the retarded growth is a result of resistance to GH or GH deficiency.…”

GH as a co-gonadotropin: the relevance of correlative changes in GH secretion and reproductive state

“…Indeed, although an agerelated increase in GH pulse amplitude is observed in normal prepubertal girls, GH pulse amplitude in girls with Turner's syndrome remains the same or even declines (Massarano et al 1989, Zadik et al 1992. These results may, however, reflect age-related increases in obesity in girls with Turner's syndrome (Cianfarani et al 1994) rather than direct effects of estrogen, since GH-releasing hormone (GHRH)-induced GH secretion and obesity are inversely related in girls with Turner's syndrome (Lu et al 1991, Reiter et al 1991. Conversely, the increased obesity in Turner's syndrome may represent the absence of GH-induced lipolysis.…”