IGF-I levels in prepubertal and pubertal children with Down syndrome.
BACKGROUND
Growth retardation is a main feature of Down syndrome but it is still unclear whether an alteration of the GH/IGF-I axis is present in this condition. Concerning IGF-I levels, they have been found reduced by some authors but normal by others.


METHODS
On these bases, IGF-I levels have been assessed from prepubertal to late pubertal stages of gonadal maturation in a large group of children and adolescents with Down syndrome (DS, 68 M, 45 F, 12.5 +/- 0.6 yr; prepubertal n = 39, pubertal n = 74) with those in a group of normal children and adolescents (NS, 75 M, 87 F; 11.1 +/- 0.4 yr; prepubertal n = 94, pubertal n = 68).


RESULTS
Within each group, IGF-I levels were gender-independent while showed age-related variations with positive association with pubertal stage--peaking up in pubertal stage IV--(DS: r = 0.6, NS: r = 0.4, both p < 0.0001) and testosterone (DS: r = 0.6, NS: r = 0.5, p < 0.001) or estradiol (DS: r = 0.6, NS: r = 0.5, p < 0.001) levels. Considering whole groups, mean IGF-I levels in DS were slightly but significantly lower than those in NS (257.9 +/- 12.5 vs 310.8 +/- 12.6 micrograms/l, p < 0.02). Analyzing individual IGF-I levels in DS with respect to normal ranges per pubertal stage, more than 85% of IGF-I levels resulted within the normal limits. These results demonstrate that IGF-I levels in DS patients are generally within the normal range--though a slight reduction of mean IGF-I levels is present--and follow normal age-related variations with clear cut increase at puberty and positive association with gonadal steroid levels.


CONCLUSIONS
This evidence points toward the need to clarify the GH/IGF-I axis function and activity in DS patients.
Ragusa
L
L
Department of Pediatrics, Oasi Institute (IRCCS), Troina, Enna.
Valetto
M R
MR
Proto
C
C
Alberti
A
A
Romano
C
C
Rossodivita
A
A
Corneli
G
G
Baffoni
C
C
Lanfranco
F
F
Aimaretti
G
G
Colabucci
F
F
Ghigo
E
E
D015415:Biomarkers / Q000097:blood; D002648:Child; D004314:Down Syndrome / Q000097:blood*; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D011627:Puberty / Q000097:blood*
D015415:Biomarkers; D007334:Insulin-Like Growth Factor I