[Differential effects on serum IGF-1 of tibolone (5 mg/day) vs combined continuous estrogen/progestagen in post menopausal women].
BACKGROUND
Tibolone has estrogenic, androgenic and progestational effects and is used in post menopausal women. It apparently has weaker effects on endometrial proliferation and mammary stimulation than conventional hormone replacement therapy.


OBJECTIVE
To compare the metabolic effects of tibolone (5 mg/day) and continuous combined conjugated estrogens/medroxyprogesterone acetate in postmenopausal women.


METHODS
Postmenopausal women, aged 45 to 60 years old, receiving estradiol valerate and medroxyprogesterone were included in the study. After a two months wash out period, in a double blind fashion, they were randomly assigned to oral tibolone 5 mg/day or equine conjugated estrogens 0.625 mg + medroxiprogesterone acetate 2.5 mg/day (ECE/MPA). At baseline, 30 and 45 days of treatment, fasting serum osteocalcin, somatomedin C (IGF-1, insulin-like growth factor 1), growth hormone (GH), and follicle stimulating hormone and first morning urine calcium and creatinine were measured.


RESULTS
Thirty women were studied. There was more than 50% fall in urine calcium with either tibolone or ECE/MPA, while fasting GH or osteocalcin did not show significant changes. Serum IGF-1 increased significantly with tibolone at basal, 30 (+109%) and 45 days of treatment and did not change in the ECE/MPA group.


CONCLUSIONS
Tibolone (5 mg/day) and ECE/MPA induced a similar reduction in urinary calcium. Tibolone increased serum IGF-1 levels. This may be due to undetected increment of overall GH secretion or to a specific action or IGF-1 generation from the liver and appears to be a novel differential effect of tibolone.
Porcile
Arnaldo
A
Departamentos de Obstetricia y Ginecología y de Medicina, Facultad de Medicina (Campus Oriente), Universidad de Chile, Santiago, Chile. aporcilej@vtr.net
Gallardo
Enrique
E
Duarte
Patricia
P
Aedo
Sócrates
S
D003271:Contraceptive Agents, Female / Q000494:pharmacology*; D004311:Double-Blind Method; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D020847:Estrogen Receptor Modulators / Q000494:pharmacology*; D005260:Female; D013006:Growth Hormone / Q000097:blood / Q000187:drug effects; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000187:drug effects* / Q000378:metabolism; D017258:Medroxyprogesterone Acetate / Q000494:pharmacology*; D008875:Middle Aged; D009652:Norpregnenes / Q000494:pharmacology*; D017698:Postmenopause / Q000097:blood*; D011446:Prospective Studies
D003271:Contraceptive Agents, Female; D020847:Estrogen Receptor Modulators; D009652:Norpregnenes; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D017258:Medroxyprogesterone Acetate; C027385:tibolone