ECE2007 Poster Presentations (1) (659 abstracts)
Impairment of GH secretion by ghrelin stimulation test in primary hyperparathyroidism (PHP)
Elisabetta Cecconi 1 , Clara Giovannetti 1 , Luca Manetti 1 , Valentina Raffaelli 1 , Massimo Procopio 2 , Ezio Ghigo 2 , Maurizio Gasperi 1 & Enio Martino 1
1Department of Endocrinology, Pisa, Italy; 2Division of Endocrinology, Turin, Italy.
Pituitary GH secretion is regulated by the interplay of at least two hypothalamic hormones, GH-releasing hormone (GHRH) and somatostatin, through their interaction with specific cell surface receptors on the anterior pituitary somatotrophs. A third type of receptor, the growth hormone secretagogue receptor, called GHS receptor type 1a (GHSR1a), was identified in the pituitary and the hypothalamus. Ghrelin is an acylated peptide produced predominantly by stomach and a natural ligand of the GHS-R1a. In HEK-293 cells expressing the GHS-R1a, ghrelin induces a biphasic cytosolic calcium elevation. We recently reported that untreated PHP patients have an impaired GH secretion, as demonstrated by a blunted GH response to maximal stimulation with GHRH+Arginine test. The aim of the present study was to evaluate effects on GH secretion induced by ghrelin in PHP. Eleven patients (2 male/9 female, age range 41–67 yrs, mean 54 yrs, BMI 26.6±3.4) with PHP were studied. The control group consisted of 35 normal age- and sex-matched subjects (12 male/23 female, age range 23–78 yrs, mean 59 yrs, BMI 26.3±3.1). Patients and controls were submitted on two separate days to ghrelin administration (1 μg/Kg iv) and to GHRH+arginine test.
Serum GH secretion was reduced (GH response to GHRH+arg test: 9.54±3.1 μg/liter) in 7 patients (64%) and normal (38.57±10.5 μg/liter) in the remaining 4 (36%); in the control group no GHD was found (peak GH 38.0±3.5 μg/liter, P<0.001).
The mean peak GH response to ghrelin in PHP was significantly lower than in normals (17.99±8.3 vs. 84.0±36 μg/L, P<0.001) in accordance to the values obtained by GHRH+arginine test.
In conclusion, this study confirms the impaired GH secretion to GHRH+Arg stimulation in PHP patients and represents the first demonstration that ghrelin administration unveils GH deficiency in PHP.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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