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The insulin-like growth factor-I system and hormone replacement therapy
H J Cardim1, C M Lopes, D Giannella-Neto
1Hospital Regional Universitário de Maringá, Rua Joaquim Nabuco, 163-apt.602, Zona 1, 87013-340 Maringá, Paraná, São Paulo, Brazil.
Objective:
To determine the effects of hormone replacement therapy on plasma concentrations of free and total insulin-like growth factor (IGF)-I, IGF binding protein (BP)-1, and IGFBP-3.
Design:
Clinical study.
Setting:
Gynecologic clinic at a university hospital.
Patient(S):
Seventy-one postmenopausal women.
Intervention(S):
Six cycles of four different hormonal replacement therapy regimens: oral conjugated estrogens, transdermal estradiol, oral conjugated estrogens and norethisterone, and transdermal estradiol and norethisterone acetate.
Main Outcome Measure(S):
Blood samples were collected before and after treatment for measurement of free and total IGF-I, IGFBP-1, and IGFBP-3.
Result(S):
Conjugated estrogen replacement therapy is associated with a decrease in plasma concentration of total IGF-I and increase in concentrations of free IGF-I and IGFBP-1. Transdermal estrogens have no effect on total and free IGF-I and IGFBP-1 concentrations. Oral norethisterone plus conjugated estrogens increased free IGF-I and IGFBP-1 concentrations but did not change IGF-I concentrations. Transdermal conjugated estrogens plus norethisterone acetate increased free IGF-I concentrations but not total IGF-I or IGFBP-1 concentrations. The plasma concentration of IGFBP-3 did not change in any group.
Conclusion(S):
Alterations in total IGF-I concentration can occur depending on the route of hormone replacement therapy administration. Free IGF-I concentrations were elevated in all study groups except that treated with transdermal estrogens.