Primary hyperparathyroidism is associated with marked impairment of GH response to acylated ghrelin.
BACKGROUND
Impaired GH secretion is a common finding in patients with primary hyperparathyroidism (PHP). Ghrelin displays strong GH-releasing action, mainly at the hypothalamic level.


OBJECTIVE
To evaluate secretory response of GH to ghrelin in PHP patients.


METHODS
Fifteen patients [11 women/4 men, mean age 54 years, range 32-70 years, body mass index (BMI) 25.0 +/- 0.7 kg/m(2)] affected with PHP due to single parathyroid adenoma and 35 normal age-matched subjects (23 women/12 men, mean age 58 years, range 35-68 years, BMI 24.1 +/- 1.1 kg/m(2)).


METHODS
A measure of 1 microg/kg body weight i.v. acylated ghrelin or 1 microg/kg body weight i.v. GH releasing hormone (GHRH) followed by 0.5 g/kg body weight i.v. arginine (ARG) hydrochloride were administered to all subjects on alternate days in order to evaluate GH response.


RESULTS
Mean serum GH peak after GHRH + ARG was 32.6 +/- 7.8 and 17.4 +/- 4.0 microg/l, in controls and PHP patients, respectively (P < 0.05). Mean serum GH peak after ghrelin was 70.4 +/- 31.5 and 16.8 +/- 1.9 microg/l, in controls and PHP patients, respectively, (P < 0.001). Using ROC curves, a serum GH peak > 22 microg/l after ghrelin stimulation might be considered as a cut-off value for identifying normal subjects. Ten (67%) PHP patients have impaired GH response to GHRH + ARG and 13 (87%) to ghrelin. Serum GH peak after ghrelin or GHRH + ARG was unrelated to serum IGF-1, PTH or ionized calcium concentrations.


CONCLUSIONS
The present data confirm that GH secretion is impaired in PHP patients using the potent GH secretagogue ghrelin and suggest that impaired GH secretion is likely due to a deleterious effect of hypercalcaemia at the hypothalamic level in PHP patients.
Cecconi
E
E
Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy.
Bogazzi
F
F
Morselli
L L
LL
Gasperi
M
M
Procopio
M
M
Gramaglia
E
E
Broglio
F
F
Giovannetti
C
C
Ghigo
E
E
Martino
E
E
D000215:Acylation; D000236:Adenoma / Q000097:blood / Q000150:complications / Q000378:metabolism; D000328:Adult; D000368:Aged; D003940:Diagnostic Techniques, Endocrine; D005260:Female; D054439:Ghrelin / Q000008:administration & dosage / Q000494:pharmacology*; D019382:Human Growth Hormone / Q000097:blood / Q000378:metabolism*; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000097:blood / Q000209:etiology / Q000378:metabolism*; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D010282:Parathyroid Neoplasms / Q000097:blood / Q000150:complications / Q000378:metabolism; D055571:Secretory Pathway / Q000187:drug effects; D012680:Sensitivity and Specificity
D054439:Ghrelin; D019382:Human Growth Hormone