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.