The short term effects of tamoxifen on bone turnover in older women

This study examined the effects of tamoxifen (TAM) on biochemical markers of bone turnover in healthy women, 20-30 yr past menopause. Ten women (mean age, 75 yr; range, 70-85 yr) were given TAM (20 mg/day) for 10 weeks. Serum and urine were collected twice at baseline, at weeks 9 and 10 of TAM treatment, and at weeks 9 and 10 post-TAM. Markers of bone formation were serum osteocalcin, total alkaline phosphatase, bone-specific alkaline phosphatase, and type I procollagen peptide. Markers of bone resorption were fasting urinary calcium, hydroxyproline, pyridinoline, and deoxypyridinoline, all corrected for urinary creatinine. Total cholesterol, triglycerides, and high density lipoproteins were measured; low density lipoprotein levels were calculated. Pyridinoline and deoxypyridinoline decreased during therapy by 23% and 25% and returned to baseline posttherapy (F = 37.01; P = 0.001), with no significant changes in urinary calcium and hydroxyproline. Markers of bone formation declined 17-36%, with a variable return toward baseline (F = 85.56; P < 0.001). Ionized calcium decreased 5% (P < 0.001) and PTH increased 21% (P = 0.05) during TAM treatment. Total cholesterol decreased 15% (P < 0.001), and calculated low density lipoprotein cholesterol decreased 22% (P < 0.001); levels of triglycerides and high density lipoprotein did not change significantly. We conclude that short term TAM treatment inhibits bone turnover in women over 70 yr of age.