Impaired GH secretion to provocative stimuli in two families with hypocalciuric hypercalcaemia.
OBJECTIVE
To determine whether hypercalcemia per se might be responsible for an impairment in GH secretion.


METHODS
Prospective study.


METHODS
Six subjects of two unrelated families with familial hypocalciuric hypercalcaemia (FHH), an autosomal dominant disorder due to inactivating mutations in the calcium receptor gene, leading to an increase in serum calcium levels and inappropriately normal serum PTH concentrations. Forty normal subjects, matched for sex and age served as controls.


METHODS
Serum GH concentrations were measured after GHRH-Arginine (GHRH-Arg) stimulation test; serum IGF-I, ACTH, cortisol, FT4, FT3, TSH, PRL, LH, FSH levels were measured under basal conditions.


RESULTS
All subjects (two male, four female, age range 24-74 years) had increased serum ionized calcium levels (range 1.36-1.56 mmol/l) and five of six patients had normal PTH levels (range for all patients was 14-68 ng/l). Basal serum GH concentrations ranged from 0.1 to 7.0 micro g/l. Mean serum GH secretory peak after GHRH-Arg stimulation test was reduced in five subjects (mean 9.3 +/- 3.6 microg/l, P < 0.006 vs. Controls, mean 67.0 +/- 44.0 microg/l, cut-off, 16.0 microg/l) and normal in one subject (38.7 microg/l). However, serum IGF-I levels were reduced only in two patients (29 and 57 microg/l) and normal in four subjects (range 127-208 microg/l). The basal secretion of the other anterior pituitary hormones was within their normal ranges.


CONCLUSIONS
The results of the present study support the concept that elevated serum calcium levels impair GH secretion. However, the clinical relevance of GH deficiency in FHH remains to be elucidated.
Cecconi
Elisabetta
E
Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy.
Bogazzi
Fausto
F
Cetani
Filomena
F
Grasso
Lucia
L
Marcocci
Claudio
C
Genovesi
Maura
M
Procopio
Massimo
M
Gasperi
Maurizio
M
Pinchera
Aldo
A
Ghigo
Ezio
E
Martino
Enio
E
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D000368:Aged; D001120:Arginine; D002118:Calcium / Q000652:urine*; D016022:Case-Control Studies; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D013007:Growth Hormone-Releasing Hormone; D019382:Human Growth Hormone / Q000097:blood / Q000172:deficiency*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D006934:Hypercalcemia / Q000503:physiopathology*; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008875:Middle Aged; D011388:Prolactin / Q000097:blood; D011446:Prospective Studies; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D014284:Triiodothyronine; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013972:Thyrotropin; D013007:Growth Hormone-Releasing Hormone; D001120:Arginine; D013974:Thyroxine; D002118:Calcium; D006854:Hydrocortisone