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Sandro Loche, Stefano Pintus, Daniela Carta, Anna Carla Muntoni, Gabriella Congiu, Patrizia Civolani and Carlo Pintor

We have evaluated the effect of acute administration of atenolol, a selective β-adrenergic antagonist, on the GH response to GHRH in nine obese children and in eight age-matched controls. The GH response to GHRH (1–29, 1 μg/kg iv), evaluated both as the GH peak and as integrated area under the curve, was significantly lower in the obese children than in the controls. Pretreatment with atenolol (50 or 100mg orally in subjects with body weight <or >40 kg, respectively, administered 120 min before the GHRH injection) significantly increased the GH response to GHRH in the obese subjects, such that their mean peak GH levels and mean integrated area under the curve after atenolol plus GHRH were similar to those of the control children after GHRH. Also in control children, atenolol caused a significant augmentation of the GH response to GHRH. Mean peak GH levels and mean integrated area under the curve after atenolol plus GHRH were significantly higher in the controls than in the obese children given the same treatment. These data show that inhibition of central β-adrenergic receptors counteracts the blunted GH response to GHRH present in the obese children. In view of the alleged mechanism of action of β-adrenergic blockade (inhibition of endogenous SRIH release), our data suggest that the somatostatinergic system is intact in obesity, and that the suppressed GH secretion is due to other causes.

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Lucia Ghizzoni, Marco Cappa, Alessandra Vottero, Graziamaria Ubertini, Daniela Carta, Natascia Di Iorgi, Valentina Gasco, Maddalena Marchesi, Vera Raggi, Anastasia Ibba, Flavia Napoli, Arianna Massimi, Mohamad Maghnie, Sandro Loche and Ottavia Porzio

Objective

Premature pubarche (PP) is the most frequent sign of nonclassic congenital adrenal hyperplasia (NCCAH) due to 21-hydroxylase deficiency in childhood. The aim of this study was to assess the relationship between the CYP21A2 genotype and baseline and ACTH-stimulated 17-hydroxyprogesterone (17-OHP) and cortisol serum levels in patients presenting with PP.

Patients and methods

A total of 152 Italian children with PP were studied. Baseline and ACTH-stimulated 17-OHP and cortisol serum levels were measured and CYP21A2 gene was genotyped in all subjects.

Results

Baseline and ACTH-stimulated serum 17-OHP levels were significantly higher in NCCAH patients than in both heterozygotes and children with idiopathic PP (IPP). Of the patient population, four NCCAH patients (7.3%) exhibited baseline 17-OHP values <2 ng/ml (6 nmol/l). An ACTH-stimulated 17-OHP cutoff level of 14 ng/ml (42 nmol/l) identified by the receiver-operating characteristics curves showed the best sensitivity (90.9%) and specificity (100%) in distinguishing NCCAH patients. This value, while correctly identifying all unaffected children, missed 9% of affected individuals. Cortisol response to ACTH stimulation was <18.2 μg/dl (500 nmol/l) in 14 NCCAH patients (28%) and none of the heterozygotes or IPP children. Among the 55 NCCAH patients, 54.5% were homozygous for mild CYP21A2 mutations, 41.8% were compound heterozygotes for one mild and one severe CYP21A2 gene mutations, and 3.6% had two severe CYP21A2 gene mutations.

Conclusion

In children with PP, baseline 17-OHP levels are not useful to rule out the diagnosis of NCCAH, which is accomplished by means of ACTH testing only. The different percentages of severe and mild CYP21A2 gene mutations found in PP children compared with adult NCCAH patients is an indirect evidence that the enzyme defect is under-diagnosed in childhood, and it might not lead to the development of hyperandrogenic symptoms in adulthood. Stress-dose glucocorticoids should be considered in patients with suboptimal cortisol response to ACTH stimulation.