Alendronate in the Treatment of Primary Hyperparathyroid-Related Osteoporosis: A 2-Year Study

We investigated the effect of alendronate on calcium, PTH, and bone mineral density in 27 female and 5 male patients with primary hyperparathyroidism. The treatment group [n = 14; T score ≤ −2.5 sd at the femoral neck (FN) or T ≤ −1.0 sd plus previous nonvertebral fracture] was given alendronate 10 mg/d for 24 months. The second group (n = 18; T score > −2.5 sd at the FN) was untreated. Biochemistry was repeated at 1.5, 3, 6, 12, 18, and 24 months, and dual-energy x-ray absorptiometry at 12 and 24 months. There were no significant between-group baseline differences in calcium, creatinine, or PTH. Alendronate-treated patients gained bone at all sites [lumbar spine (LS), 1 yr gain, +7.3 ± 1.7%; P < 0.001; 2 yr, +7.3 ± 3.1%; P = 0.04). Untreated patients gained bone at the LS over 2 yr (+4.0 ± 1.8%; P = 0.03) but lost bone elsewhere. Calcium fell nonsignificantly in the alendronate group between baseline (2.84 ± 0.12 mmol/liter) and 6 wk (2.76 ± 0.09 mmol/liter), with a nonsignificant rise in PTH (baseline, 103.5 ± 14.6 ng/liter; 6 wk, 116.7 ± 15.6 ng/liter). By 3 months, values had reverted to baseline. In primary hyperparathyroidism, alendronate is well tolerated and significantly improves bone mineral density at the LS (with lesser gains at FN and radius), especially within the first year of treatment. Short-term changes in calcium and PTH resolve by 3 months.