DECREASE OF BONE-MINERAL DENSITY DURING ESTROGEN SUBSTITUTION THERAPY

A decrease in bone mineral density (BMD) in patients treated with horm one replacement therapy (HRT) is sometimes observed in clinical practi ce. In order to assess the frequency and the characteristics of these cases, we reviewed the data of 102 women treated with HRT for more tha n 2 years, and who had undergone at least 3 lumbar BMD measurements du ring that period. For each patient, a linear function was fitted to th e BMD data in relation to time. The slope was calculated. There was an overall gain in BMD during treatment, mean (+/- S.E.M.) values of slo pe 0.007 g/cm(2)/year (+/- 0.002). Fifty-three patients had a slope hi gher than 0.005,28 a slope close to 0 (between 0.005 and -0.005) and 2 1 a slope lower than -0.005. By dividing the patients in tertiles of s lopes (tertile 1: slope < 0; tertile II: 0 < slope < 0.011; tertile II I: slope > 0.011), significant differences were observed between the t hree groups of slope for the initial BMD (P < 0.001), hydroxyproline/c reatinine ratio (P < 0.01), weight, DHEAS and alkaline phosphatase (P < 0.05). Only 1 of the 15 patients with a low bone mass (lower than me an +/- 1 S.D.) had a negative slope, while 9 of the 16 with a high-bon e mass (higher than mean +/- 1 S.D.), had a negative slope. Under HRT, about 21% of postmenopausal women have a slight decrease in BMD as as sessed by DPA. Because of the DPA coefficient of variation, however, t he exact number of bone losers cannot be determined. Nevertheless, the present study suggests that patients with low bone mass are likely to respond better than patients with high bone mass.