[Is beta 2-microglobulin a marker of bone remodeling in Paget's disease of bone?].

BACKGROUND

Some authors found in Paget's disease bone and in osteoporosis elevated serum levels of beta-2-microglobulin. The objective of the present work was to assess whether in patients with a different activity of Paget's disease of bone the serum values of beta-2-microglobulin before treatment and after 1,6 and 12 month's treatment with pamidronate can serve as a marker of bone metabolism and whether pamidronate treatment has an impact on the serum concentration of beta-2-microglobulin.

METHODS AND RESULTS

35 patients with Paget's disease of bone (25 men and 10 women, mean age 64 and 72 years resp.) were divided into three groups with a different activity of the disease based on the values with a different activity of the disease based on the values of the bone isoenzyme of alkaline phosphatase in serum. In all serum concentrations of beta-2- microglobulin were examined before and during treatment with pamidronate. The control group was formed by five healthy men and five healthy women, mean age 65 years, and a special group of weight drug addicts dependent on opiates (5 men and 3 women, mean age 26 years). For assessment of beta-2-microglobulin in serum the enzymic immunoassay and fluorescence detection were employed, using Abbott, IMX, MEIA system kits. The serum concentrations of the bone isoenzyme of alkaline phosphatase were assessed by the method used at the Third Medical Clinic of the First Medical Faculty Charles University Prague (8). For statistical processing the non-parametric Friedman test was used to assess the significance of differences between means (p < 0.01) and simultaneous testing at the 5% level of significance. Serum concentrations of beta-2-microglobulin in patients with Paget's disease of bone with a low activity before treatment and after 1, 6 and 12 months of pamidronate treatment were 2.02 +/- 0.9, 2.10 +/- 1.2, 1.9 +/- 1.1 and 1.98 +/- 1.4 ng/l. In patients with a medium activity of the disease the values were 1.80 +/- 0.5, 1.78 +/- 1.02, 2.2 +/- 1.1 and 1.50 +/- 0.7 ng/l. The values in patients with a high activity of the disease were 1.9 +/- 0.9, 2.02 +/- 1.2, 2.40 +/- 0.8 and 2.45 +/- 1.01 ng/l. The values of beta2-microglobulin did not differ when compared with normal values (p < 0,1).

CONCLUSIONS

In patients with Paget's disease bone regardless of the different activity of the disease before treatment or after short-term or prolonged pamidronate treatment no differences were revealed in the serum levels of beta-2-microglobulin. Pamidronate treatment did not influence the concentration of beta2-microglobulin and assessment of beta2-microglobulin in Paget's disease bone is no asset.