title: Diagnosing growth hormone deficiency: the value of short-term hypocaloric diet.
abstract: In the attempt to define possible causes of false positive GH deficiency, the role of caloric intake on GH determination was explored. The serum GH responses to insulin-induced hypoglycemia or arginine were assessed before and after 3 days of a hypocaloric diet in 23 prepubertal children of normal weight, aged 6.7-11.9 yr. Seventeen had short stature and a GH response to insulin and arginine below 10 micrograms/L, and 6 controls had normal stature and a GH peak above 10 micrograms/L in response to arginine. After diet, the serum peak GH and the area under the curve increased in both the patients (P < 0.0005 and P < 0.0005) and the controls (P < 0.005 and P < 0.025) with a GH peak greater than 10 micrograms/L in 11 of 17 patients. The patients with a persistent GH response below 10 micrograms/L also had lower mean 12-h overnight GH levels (P < 0.0005), whereas those with a normal GH response after diet had an overnight GH level greater than 3 micrograms/L. In the patients, the mean nighttime GH concentrations correlated with the serum GH peak (r = 0.85; P < 0.005) and with the area under the curve after the diet (r = 0.65; P < 0.025). The diet induced changes in plasma insulin-like growth factor-I, GH-releasing hormone levels, basal blood sugar and the nadir level obtained during insulin stimulation, total T3, and rT3. Height increased significantly during 1 and 2 yr (P < 0.005) of GH treatment only in patients with a GH response below 10 micrograms/L after the diet. These data are consistent with the hypothesis that the GH response to stimulation is strongly calorie dependent and that 3 days of a hypocaloric diet can increase the number and height of GH peaks and the total GH responses to insulin and arginine. The clear correlation of the GH response to stimulation after a hypocaloric diet with the mean nighttime GH and also with the growth response to GH treatment indicates that GH deficiency may be overdiagnosed in many children with short stature.
authors.affiliation: Department of Pediatrics, University of Pavia, Istituto di Ricovero e Cura a Carattere Scientifico Policlinico S. Matteo, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Maghnie
authors.forename: A
authors.initials: A
authors.lastname: Valtorta
authors.forename: A
authors.initials: A
authors.lastname: Moretta
authors.forename: D
authors.initials: D
authors.lastname: Larizza
authors.forename: P
authors.initials: P
authors.lastname: Preti
authors.forename: G
authors.initials: G
authors.lastname: Palladini
authors.forename: S
authors.initials: S
authors.lastname: Calcante
authors.forename: F
authors.initials: F
authors.lastname: Severi
mesh_terms: D001120:Arginine / Q000494:pharmacology; D001786:Blood Glucose / Q000032:analysis; D002648:Child; D002940:Circadian Rhythm; D004032:Diet; D002149:Energy Intake; D005260:Female; D013006:Growth Hormone / Q000097:blood / Q000172:deficiency*; D013007:Growth Hormone-Releasing Hormone / Q000097:blood; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D008297:Male; D010903:Pituitary Gland, Anterior / Q000473:pathology
chemical_list: D001786:Blood Glucose; D007328:Insulin; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D001120:Arginine