Enhanced growth hormone (GH) responsiveness to GH-releasing hormone after dietary restriction in patients with Cushing's syndrome.
OBJECTIVE
In patients with Cushing's syndrome, decreased growth hormone (GH) secretion is observed although the basic mechanism is not yet understood. A short-term hypocaloric diet is known to increase both spontaneous and GHRH-stimulated GH secretion in normal subjects. In order to gain further insight into the altered GH secretion in patients with Cushing's syndrome, we assessed the effect of a short-term hypocaloric diet on GH responses to GHRH in these patients.


METHODS
Two GHRH tests (1 microgram/kg i.v.) were performed, the first under basal conditions (normocaloric diet) and the second after a 3-day hypocaloric diet (650 cal/day).


METHODS
Six female patients with untreated Cushing's disease.


METHODS
Plasma GH levels were measured by immunoradiometric assay.


RESULTS
GHRH-induced GH release was impaired in patients with Cushing's disease on a normal diet (mean peak 12.4 +/- 6.4 mU/l, area under the curve (AUC) 744 +/- 332 mU/l/120 min). Following a hypocaloric diet, GH responses to GHRH were markedly enhanced in the same group of patients (mean peak 46.2 +/- 14.8 mU/l, AUC 3142 +/- 1032 mU/l/120 min, P < 0.05).


CONCLUSIONS
This study demonstrates that in patients with Cushing's disease the somatotroph hyporesponsiveness to growth hormone releasing home is improved after a short-term hypocaloric diet. Therefore, blunted growth-hormone secretion in chronic hypercortisolism is a potentially reversible state and the secretory capacity of the somatotroph appears not to be severely compromised in patients with Cushing's disease.
Leal-Cerro
A
A
Department of Endocrinology, Hospital Virgen del Rocio, Sevilla, Spain.
Venegas
E
E
Garcia-Pesquera
F
F
Jimenez
L M
LM
Astorga
R
R
Casanueva
F F
FF
Dieguez
C
C
D000293:Adolescent; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D003480:Cushing Syndrome / Q000097:blood / Q000378:metabolism* / Q000652:urine; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D005260:Female; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood / Q000652:urine; D008875:Middle Aged; D017337:Sermorelin
D004040:Dietary Carbohydrates; D017337:Sermorelin; D000324:Adrenocorticotropic Hormone; D013006:Growth Hormone; D006854:Hydrocortisone