[Low sensitivity of IGF-I, IGFBP-3 and urinary GH in the diagnosis of growth hormone insufficiency in slowly-growing short-statured boys. Grupo Español de Estudio de la Talla Baja].
BACKGROUND
The usefulness of IGF-I, IGFBP-3, and the urinary GH excretion in the diagnostic evaluation of growth retardation in boys with short stature was studied.


METHODS
Serum samples from two GH-stimulation tests and two 24-h urine samples were sent to a Central Laboratory to measure serum and urinary GH, serum IGF-I, IGFBP-3 and GHBP, both in absolute and standardized values (Z-score). Short children were classified as growth hormone deficient (GHD) (n = 25), and idiopathic short statured (ISS) (n = 54), on the basis of the peak stimulated GH concentration of < 7.5 microg/l or > or = 7.5 microg/l respectively. A group of 15 normally growing children and adolescents was also included.


RESULTS
Height-velocity standard deviation score (HV)-SDS was lower and body mass index higher in GHD than ISS. Standardized IGF-I differed significantly by ANOVA among the three groups (p = 0.001). Multiple stepwise linear regression analysis with HV-SDS as dependent variable showed IGF-I SDS as the best predictor followed by peak GH clonidine response and uGH excretion. ROC curves showed optimum cut-off level for IGF-I SDS as 2.05 (sensitivity: 32%, specificity: 90%) and 1.14 for IGFBP-3 SDS sensitivity: 28%, specificity: 94%).


CONCLUSIONS
Standardized IGF-I and IGFBP-3 measurements were highly efficient only in diagnosis of severe GHD, but they show low sensitivity for the diagnosis of isolated idiopathic GHD as defined according to the low GH response to stimulation tests.
Audí
L
L
Departamento de Pediatría. Hospital Vall d'Hebron. Barcelona. laudi@cs.vhebron.es
Antonia Llopis
M
M
Luisa Granada
M
M
Hermoso
F
F
del Valle
J
J
Dolores Rodríguez-Arnao
M
M
Bel
J
J
Luzuriaga
C
C
Gallego
E
E
Marín
F
F
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D006130:Growth Disorders / Q000175:diagnosis / Q000378:metabolism*; D013006:Growth Hormone / Q000097:blood / Q000172:deficiency* / Q000652:urine*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D012044:Regression Analysis; D012680:Sensitivity and Specificity
D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone