title: New approach to the diagnosis of growth hormone deficiency in adults.
abstract: Pyridostigmine (PD), a muscarinic cholinergic agonist, and arginine (ARG) clearly increase the growth hormone (GH) response to growth hormone-releasing hormone (GHRH) in man. The current study was undertaken to investigate the value and safety of PD + GHRH and ARG + GHRH tests as well as the measurement of serum insulin-like growth factor I (IGF-I) in diagnosing GH deficiency in adults. Fifty-four patients considered GH deficient from extensive organic or idiopathic pituitary disease and 326 healthy adults were studied. The IGF-I concentrations were lower than the 3rd percentile of normal values in only 31 of the 54 (57.4%) patients with hypopituitarism. However, the IGF-I levels in hypopituitary patients and in normal subjects overlapped more frequently between 41 and 60 years (50%) and between 61 and 80 years (92.3%) as opposed to between 20 and 40 years (8.6%). In contrast to the IGF-I measurement, the ranges of peak GH responses to PD + GHRH and ARG + GHRH tests were clearly differentiated between the hypopituitary (0.2-6.8 and 0.1-9.5 microg/l, respectively) and normal (17.7-114 and 16.1-119 microg/l, respectively). However, the PD + GHRH test was reliable only in subjects of 20-40 years of age. In conclusion, IGF-I measurement had no value in the diagnosis of GH deficiency in adults aged over 40 years, but is reliable enough when young adults of 20-40 years of age are considered. Both PD + GHRH and ARG + GHRH testing should be considered more reliable biochemical measurements of GH deficiency. In contrast to the PD + GHRH test, the ARG + GHRH test is reliable throughout the adult lifespan and appears to be the most appropriate for patient compliance and safety.
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, University of Turin, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Ghigo
authors.forename: G
authors.initials: G
authors.lastname: Aimaretti
authors.forename: L
authors.initials: L
authors.lastname: Gianotti
authors.forename: J
authors.initials: J
authors.lastname: Bellone
authors.forename: E
authors.initials: E
authors.lastname: Arvat
authors.forename: F
authors.initials: F
authors.lastname: Camanni
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001120:Arginine; D005260:Female; D013006:Growth Hormone / Q000172:deficiency*; D013007:Growth Hormone-Releasing Hormone / Q000009:adverse effects; D006801:Humans; D007018:Hypopituitarism / Q000097:blood / Q000175:diagnosis; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D011729:Pyridostigmine Bromide / Q000009:adverse effects
chemical_list: D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D001120:Arginine; D011729:Pyridostigmine Bromide