Basal IGF-I levels and the GH response to at least two among provocative stimuli such as clonidine (CLO, Catapresan, 150 mcg/m2 p.o.), GHRH (1 mcg/kg i.v.)+arginine (ARG, 0.5 g/kg i.v. infusion during 30 min) and GHRH+pyridostigmine (PD, Mestinon cpr 60 mg p.o.) have been evaluated in 43 children with Prader-Willi syndrome (PWS, 17 males and 26 females, age 3-22 yr, 7 normal weight and 36 obese PWS), in 25 normal short children (NC, 17 males and 8 females, 7.7-18.5 yr) and in 24 children with simple obesity (OB, 14 males, 10 females, 7.7-21.5 yr). Both normal weight and obese PWS had mean IGF-I levels lower than those recorded in NC (p<0.001) and OB (p<0.001). The GH responses to GHRH+ARG and GHRH+PD in NC were similar and higher than that to CLO (p<0.001). In PWS the GH response to GHRH+ARG was higher than that to GHRH+PD (p<0.001) which, in turn, was higher than that to CLO (p<0.001); these responses in PWS were lower than those in normal children (p<0.02) and similar to those in OB. In normal weight PWS the GH responses to GHRH+ARG and to GHRH+PD were similar and higher than to CLO (p<0.05); however, each provocative stimulus elicited a GH rise lower than that in NC (p<0.05). In obese PWS as well as in OB the GH response to GHRH+ARG was higher than that to GHRH+PD (p<0.02) which, in turn, was higher than that to CLO (p<0.001); all GH responses in obese PWS and OB were lower than those in NC (p<0.001) but similar to those in normal weight PWS. In conclusion, patients with PWS show clear reduction of IGF-I levels as well as of the somatotroph responsiveness to provocative stimuli independently of body weight excess. These results strengthen the hypothesis that PWS syndrome is frequently connotated by GH insufficiency.

GH/IGF-I axis in Prader-Willi syndrome: Evaluation of IGF-I levels and of the somatotroph responsiveness to various provocative stimuli

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/pdf/prader-willi-syndrome-genotype-and-phenotype-at-adult-age-3bxkodo627.pdf

Prader-Willi syndrome : genotype and phenotype at adult age

Background: In adults with Prader-Willi syndrome (PWS), limited information is available about pituitary function, more specifically the prevalence of growth hormone deficiency (GHD

The GH/IGF-I Axis and Pituitary Function and Size in Adults with Prader-Willi Syndrome

The spontaneous growth of 315 patients (109 girls and 208 boys) with Prader-Willi syndrome (PWS) was analysed in a mixed longitudinal and cross-sectional manner. 33 patients were seen in the department between 1970 and 1994; height and weight of 76 patients from Germany were evaluated by means of a questionnaire with detailed measuring instructions, and 206 definite cases were added from the literature. Mean (±SD) length of newborn babies with PWS was 50.2 ± 2.8 cm (145 boys) and 48.9 ± 3.3 cm (79 girls). Mean weight at birth was 2945 ± 570 g in boys and 2782 ± 594 g in girls. During the 1st year, the children's growth was nearly normal, thereafter short stature was present in approximately 50% of PWS patients. Between 3 and 13 years of age, the 50th percentile for height in PWS is roughly identical with the 3rd percentile in healthy controls. Body weight was normal for all boys and girls during the first 2 years. Thereafter, a rapid weight gain occurred; after an age of 10 years weight-for-height index in nearly all patients exceeded the normal range. The extent of pubertal growth was reduced for the group. Mean adult height was 161.6 ± 8.1 cm (23 males) and 150.2 ± 5.5 cm (21 females). Head circumference for age was normal for boys and girls.

Reference values for height and weight in Prader-Willi syndrome based on 315 patients.

Low somatotrope responsiveness to secretagogues has been reported in patients affected by Prader-Labhard-Willi Syndrome (PLWS). In normal subjects, GH response to GHRH is known to be greatly potentiated to the same extent by pyridostigmine (PD) or arginine (ARG) which probably act via inhibition of hypothalamic somatostatin release. To clarify somatotrope responsiveness in 7 PLWS patients, we studied GH response to GHRH alone and to GHRH combined with PD or ARG. Eight normal short children were studied as controls (NC). GH response to GHRH in PLWS was lower than in NC (AUC: 615 +/- 205 micrograms/l.h, vs 1271 +/- 333 micrograms/l.h, p < 0.02). In NC, the GHRH-induced GH rise was potentiated to the same extent by PD or ARG. In contrast, in PLWS PD failed to increase the GH response to GHRH (AUC: 615 +/- 205 micrograms/l.h vs 621 +/- 176 micrograms/l.h, n.s.) which was enhanced by ARG (AUC: 615 +/- 205 micrograms/l.h vs 1633 +/- 425 micrograms/l.h, p < 0.02). However, the GH response to GHRH + ARG in PLWS was lower than in NC. In conclusion, our results demonstrate that in PLWS the low somatotrope responsiveness to GHRH is not enhanced by cholinergic potentiation while it is increased by arginine.

GH secretion in Prader-Labhard-Willi syndrome: somatotrope responsiveness to GHRH is enhanced by arginine but not by pyridostigmine.

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GH secretion in Prader-Labhard-Willi syndrome: somatotrope responsiveness to GHRH is enhanced by arginine but not by pyridostigmine.