Ceci Mendes Carvalho Lopes

The insulin-like growth factor-I system and hormone replacement therapy.

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.