A one-year follow-up on the effects of raloxifene on thyroid function in postmenopausal women.
OBJECTIVE
Estrogens increase serum thyroxine-binding globulin (TBG) and total thyroxine (TT4) concentrations. Serum free thyroxine (FT4) concentrations, however, remain normal. Raloxifene (RAL) is a selective estrogen receptor modulator used to treat postmenopausal osteoporosis. Data on the long-term effects of RAL on thyroid physiology are scanty. We evaluated the effects of RAL administration for 1 year on thyroid function in osteopenic, postmenopausal women.


METHODS
Fifty osteopenic, postmenopausal women were randomly assigned to receive either RAL (60 mg/day, n = 25) or placebo (PL, n = 25) for 1 year, in a double-blind study. Measurements of serum TBG, TT4, FT4, thyroid-stimulating hormone (TSH), thyroid hormone-binding ratio (THBR), FT4 index (FT4-I) and TT4/TBG ratio were carried out at baseline and after 4 and 12 months of therapy.


RESULTS
Baseline values were similar in both treatment groups. Serum TBG concentrations were increased during RAL treatment from baseline values of 29.60 +/- 0.9 microg/mL to 31.45 +/- 1.33 and 32.34 +/- 1.37 microg/mL at 4 months and 1 year, respectively (P < 0.05, baseline v 1-year values) but were unchanged during PL treatment. A small, insignificant increase in TT4 and TSH concentrations occurred in the RAL group and no changes in the PL group. All other values were unchanged during either treatment.


CONCLUSIONS
These results demonstrate that RAL significantly increased serum TBG levels, but the changes were small and not accompanied by changes in FT4-I, FT4, or TSH concentrations, suggesting that long-term RAL treatment is unlikely to clinically affect the thyroid status in euthyroid, postmenopausal women.
Ceresini
Graziano
G
Department of Internal Medicine and Biomedical Sciences, University of Parma, Parma, Italy. ceresini@unipr.it
Morganti
Simonetta
S
Rebecchi
Isabella
I
Bertone
Luca
L
Ceda
Gian Paolo
GP
Bacchi-Modena
Alberto
A
Sgarabotto
Mariapaola
M
Baldini
Monica
M
Ablondi
Fabrizio
F
Valenti
Giorgio
G
Braverman
Lewis E
LE
D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000188:drug therapy*; D017698:Postmenopause; D020849:Raloxifene Hydrochloride / Q000494:pharmacology / Q000627:therapeutic use*; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology / Q000627:therapeutic use*; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000187:drug effects*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013975:Thyroxine-Binding Proteins / Q000378:metabolism; D016896:Treatment Outcome
D020845:Selective Estrogen Receptor Modulators; D013975:Thyroxine-Binding Proteins; D020849:Raloxifene Hydrochloride; D013972:Thyrotropin; D013974:Thyroxine