Oestrogen has no short-term effect on intestinal strontium absorption in healthy postmenopausal women.
OBJECTIVE
Impaired intestinal calcium absorption in postmenopausal women is often indirectly linked to decreased serum 1,25(OH)2D or to intestinal resistance to its action rather than directly to low circulating oestrogen levels following the menopause. The purpose of this clinical study was to investigate the short-term effect of oral 17 beta-oestradiol on intestinal calcium absorption, with strontium as a marker.


METHODS
Twenty-five healthy postmenopausal women participated in this randomised double blind placebo controlled clinical trial. Twelve women received oestradiol therapy (2 mg/day) and thirteen placebo for 2 months. Fractional strontium absorption (Fc240) was assessed at baseline and after 2 months of oestradiol/placebo therapy.


RESULTS
Intestinal strontium absorption (Fc240) was unchanged after treatment with 17 beta-oestradiol (10.1 +/- 5.0 vs. 10.2 +/- 3.8(%)). Serum total calcitriol (1,25(OH)2D) was unchanged after treatment with placebo (88 +/- 22 vs. 79 +/- 21 (pmol/l)) but increased after treatment with oestradiol (88 +/- 30 vs. 116 +/- 33 (pmol/l); P < 0.005). Serum vitamin D binding protein (DBP) increased after oestradiol but not after placebo treatment. The free serum 1,25(OH)2D index was calculated. This index did not change after oestrogen therapy (1.6 +/- 0.5 vs. 1.8 +/- 0.5).


CONCLUSIONS
In healthy postmenopausal women, short-term suppletion with exogenous oral oestrogen did not influence intestinal calcium absorption as measured by the strontium absorption test.
ten Bolscher
M
M
Department of Endocrinology, University Hospital Vrije Universiteit, Amsterdam, The Netherlands. M.tenBolscher@azvu.nl
de Valk-de Roo
G W
GW
Barto
R
R
van der Vijgh
W J
WJ
Netelenbos
J C
JC
D000284:Administration, Oral; D015415:Biomarkers / Q000097:blood; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000493:pharmacokinetics*; D004311:Double-Blind Method; D004958:Estradiol / Q000008:administration & dosage* / Q000494:pharmacology; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood*; D013324:Strontium / Q000493:pharmacokinetics*; D014809:Vitamin D-Binding Protein / Q000097:blood
D015415:Biomarkers; D014809:Vitamin D-Binding Protein; D004958:Estradiol; D002117:Calcitriol; D002118:Calcium; D013324:Strontium