Vol. 276, Issue 6, E1009-E1013, June 1999
Dose-response study of GH effects on circulating IGF-I and
IGFBP-3 levels in healthy young men and women
E.
Ghigo1,
G.
Aimaretti1,
M.
Maccario1,
G.
Fanciulli2,
E.
Arvat1,
F.
Minuto3,
G.
Giordano3,
G.
Delitala2, and
F.
Camanni1
1 Division of Endocrinology,
Department of Internal Medicine, University of Turin, 10126 Torino;
2 Division of Internal Medicine,
University of Sassari, 07100 Sassari; and
3 Department of Endocrinology and
Metabolism, University of Genoa, 16100 Genoa, Italy
The aim of our
study was to define the dose-response effect of a short-term treatment
with different recombinant human growth hormone (rhGH) doses (1.25, 2.5, 5.0, 10.0, and 20.0 µg · kg
1 · day1
for 4 days) on insulin-like growth factor I (IGF-I) and insulin-like growth factor-binding protein (IGFBP)-3 levels in 21 normal young adults of both sexes. The dose of 1.25 µg/kg rhGH did not modify IGF-I levels. The dose of 2.5 µg/kg rhGH significantly increased IGF-I levels in men (P < 0.05) but
not in women, whereas the higher doses increased IGF-I levels in both
sexes (P < 0.002). IGFBP-3 levels
were not modified by 1.25 or 2.5 µg/kg rhGH in either sex. On the
other hand, 5.0 µg/kg increased IGFBP-3 levels in men
(P < 0.05) but not in women, whereas
the higher doses increased IGFBP-3 levels similarly in both sexes
(P < 0.02). In conclusion, our results demonstrate that IGF-I and IGFBP-3 responses to rhGH are dose
and sex dependent. However, IGFBP-3 is less sensitive than IGF-I to
rhGH stimulation.
recombinant human growth hormone; insulin-like growth factor I; insulin-like growth factor-binding protein-3; insulin-like growth
factor I generation test
