Changes in body composition during post-menopausal hormone therapy: a 2 year prospective study

BACKGROUND: Post-menopausal hormone therapy (pHT) induces changes in both body composition and bone mineral density (BMD). METHODS: In 109 post-menopausal women beginning either tibolone 2.5 mg (n=29), tibolone 1.25 mg (n=42) or estradiol 2 mg plus norethisterone acetate 1 mg (E2 + NETA) (n=38), we assessed body composition, total and regional BMD by dual energy X-ray absorptiometry, and the serum bone alkaline phosphatase (BAP), osteocalcin and the urinary excretion to type I collagen C-telopeptide (CTX) at baseline and after 2 years. RESULTS: At baseline, BMD at all sites correlated negatively with age and years since menopause, and positively with lean mass and fat mass (r=0.42, P<0.001 and r=0.26, P=0.006 at the total femur). During treatment, BMD increased at all sites (P<0.001), and serum BAP, osteocalcin, and urinary CTX decreased in all groups (P<0.001). Lean mass increased whereas android fat and android obesity index decreased. The increase in BMD at all sites correlated positively with changes of lean mass at 2 years. CONCLUSIONS: Both fat mass and lean mass are related to BMD in post-menopausal women, the relationship being strongest with lean mass; an increase in lean mass and a change in distribution of body fat are observed during treatment with E2 + NETA and tibolone.