REDUCED GROWTH-HORMONE SECRETION IN TURNER SYNDROME - IS BODY-WEIGHT A KEY FACTOR

The age-related decline in spontaneous growth hormone (GH) secretion h as been suggested to cause growth failure in girls with Turner syndrom e (TS). We studied 23 girls (mean age +/- SD: 11.1 +/- 2.7 years) diag nosed to have TS by karyotype analysis. The control group consisted of 18 prepubertal age matched subjects (10.7 +/- 2.5 years) with growth retardation due to familial short stature and/or constitutional growth delay. In addition, Is children (10.9 +/- 3.3 years) diagnosed to hav e GH deficiency by two different provocative tests were chosen as a fu rther comparison group. Spontaneous 12-hour nocturnal GH secretion was assessed by RIA at 30-min intervals. Plasma insulin-like growth facto r 1 (IGF-1) levels were determined by RIA after acid-ethanol extractio n. Girls with TS had a percentage of ideal body weight significantly h igher than controls (p < 0.0001) and showed spontaneous GH secretion s ignificantly lower than controls (mean +/- SD: 3.2 +/- 1.6 in TS vs. 5 .5 +/- 1.3 mu g/l in controls; p < 0.0001) but higher than GH-deficien t patients (1.3 +/- 0.8 mu g/l; p < 0.0001). No significant difference was found in IGF-1 levels between TS patients and controls, whereas G H-deficient children showed IGF-1 levels significantly lower than thos e of TS patients (p < 0.0005). As expected, GH concentrations correlat ed with bone age in controls (r = 0.51, p < 0.05), whereas no relation ship was seen in TS. Interestingly, in TS, GH levels were negatively r elated to the percentage of ideal body weight (r = -0.43, p < 0.05). T he finding of GH levels intermediate between control and GH-deficient patients together with normal IGF-1 concentrations, questions the exis tence of a 'classical' GH insufficiency in TS girls. This study confir ms that weight excess is a common feature of TS girls at pubertal age and suggests that the reduced GH secretion might be due, at least in p art, to obesity.