SODIUM MONOFLUOROPHOSPHATE INCREASES VERTEBRAL BONE-MINERAL DENSITY IN PATIENTS WITH CORTICOSTEROID-INDUCED OSTEOPOROSIS

Corticosteroid-induced osteoporosis, which particularly affects the ax ial skeleton and the proximal femur, is characterized by a state of lo w bone remodelling. Fluoride is a potent stimulator of trabecular bone formation which could potentially be useful in the treatment of corti costeroid-induced osteoporosis. We investigated the effects of sodium monofluorophosphate (26 mg/day of fluoride) combined with 1000 mg of c alcium (MFP-calcium-treated group), or of calcium alone (control), giv en for 18 months, on bone mineral density (BMD) of lumbar spine (LS), femoral neck (FN) and midfemoral shaft (FS) in 48 patients with cortic osteroid-induced osteoporosis. Mean ages were 49.4 +/- 3.1 and 51.6 +/ - 3.0 years (mean +/- SEM), duration of corticosteroid therapy 7.5 +/- 1.8 and 9.3 +/- 1.7 years, and mean daily dose of prednisone 18.2 +/- 2.3 and 12.1 +/- 1.1 mg in the MFP-calcium-treated group and controls , respectively. Initial BMDs (expressed as the Z-core, i.e. the differ ence in standard deviations from age- and sex-matched normal subjects) were -1.5 +/- 0.2 and -1.2 +/- 0.2 for LS, -1.4 +/- 0.2 and -1.3 +/- 0.2 for FN, and -0.8 +/- 0.3 and -0.6 +/- 0.3 for FS, in the MFP-calci um-treated group and controls, respectively. Analysis by linear regres sion of 6-monthly measurement values revealed BMD changes of +7.8 +/- 2.2 versus + 3.6 +/- 1.3% (p < 0.02) for LS, -1.5 +/- 1.8 versus + 0.9 +/- 1.8% for FN, and -1.1 +/- 1.1 versus -0.5 +/- 1.4% for FS after 1 8 months of follow-up in the MFP-calcium-treated group and controls, r espectively. For comparison, 17 patients with idiopathic osteoporosis (mean age 63.9 +/- 2.0 years), with initial BMDs of -1.3 +/- 0.4, -1.6 +/- 0.3 and -0.8 +/- 0.4 (Z-score for LS, FN and FS, respectively), r eceived MFP and calcium for 22.1 +/- 1.7 months. BMD changes in idiopa thic osteoporosis were +9.3 +/- 2.7% (p < 0.005), -1.3 +/- 2.0% and +0 .6 +/- 0.9% for LS, FN and FS, respectively. These results indicate th at the combination sodium monofluorophosphate and calcium was more eff icient than calcium alone in increasing lumbar spine BMD in patients w ith corticosteroid-induced osteoporosis; neither femoral neck nor femo ral shaft BMD was affected. Moreover, these effects were similar in pa tients with corticosteroid-induced and idiopathic osteoporosis.