Analysis of the Increase in Bone Mineral Density After Surgical Treatment of Primary Hyperparathyroidism.

AIM: To analyze the effect of the surgery in bone mineral density (BMD) and to study the value of preoperative clinical and analytical factors as predictors of bone increase.

MATERIAL AND METHODS: Prospective observational study. Postmenopausal women who were operated for primary hyperparathyroidism were included. A bone densitometry of the lumbar spine and femoral neck and analytical determinations (parathyroid hormone [PTH], alkaline phosphatase, albumin, phosphate, creatinine, 25-hydroxy-vitamin D3, creatinine clearance, and calciuria) were performed previous to the intervention and after 12 months from surgery.

RESULTS: Two hundred and twenty-eight patients were operated on for primary hyperparathyroidism were considered for study, 108 postmenopausal women entered in the final analysis. The mean age was 63 ± 7 yr. After the intervention, a significant increase in BMD was observed in the two locations analyzed, although this increase was significant greater at the level of the lumbar spine. In the lumbar spine, 68 patients (63%) recorded a significant postoperative increase in bone density. Median postoperative BMD was 0.860 g/cm2 (interquartile range: 0.93). The observed average percentage of density increase was 6.63 ± 17.9. In femoral neck, 61 patients (56.6%) registered a significant increase in bone density. Median postoperative BMD value was 0.741 g/cm2 (interquartile range: 0.76). The average percentage of density increase was 3.19 ± 17.9. In the lumbar spine, patients with osteoporosis before surgery increased postoperative BMD more frequently than those with osteopenia or normal density. Patients who increased BMD preoperatively presented lower bone density levels both in the lumbar spine (median: 0.775, interquartile range: 0.882) and in the hip (median: 0.655, interquartile range: 0.562) than patients in whom it was not observed postoperative increase. PTH preoperative serum was lower among patients who increased bone density in the femur (median: 141 pg/ml, interquartile range: 291) than among those who did not (median: 152 pg/ml, interquartile range: 342) (p = 0.01). In the multivariate analysis, the increase in BMD in the lumbar spine was related to preoperative BMD (odds ratio [OR] 0.084, 95% confidence interval [CI]: 0.007-0.961); in femoral neck it was related to preoperative BMD (OR 0.001; 95% CI: 0.0-0.028) and to the preoperative PTH serum concentration (OR 0.99; 95% CI: 0.98-0.99).

CONCLUSIONS: After surgery, a significant increase in BMD was observed in the lumbar spine and femoral neck. In the multivariate analysis, preoperative bone density was the factor that showed the highest predictive value of the increase in BMD after surgery.