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

24-hour Urine Calcium Predicts Reduced Fracture Incidence and Improved Bone Mineral Density After Surgery for Primary Hyperparathyroidism

CONTEXT

Contemporary patients with primary hyperparathyroidism are diagnosed with milder disease than previously. Clinical and biochemical factors predictors with an impact on fracture incidence and bone mineral density after surgery have not been firmly established.

OBJECTIVE

To investigate predictors of fracture incidence and bone mineral density preoperatively and after surgery for primary hyperparathyroidism (pHPT).

DESIGN

Prospectively collected surgical cohort with matched population controls. Data were cross-linked with the Swedish National Patient Register, the Prescribed Drug Register, and the Cause of Death Register.

SETTING

Tertiary referral center.

PATIENTS OR OTHER PARTICIPANTS

Seven hundred nine patients with successful parathyroidectomy for pHPT and 2112 controls matched on sex, age, and municipality were included in the study.

MAIN OUTCOME MEASURES

Fracture incidence, absolute change, and ≥2.77% increase in bone mineral density of femoral neck, L2-L4, and distal third of radius at 1-year follow-up.

RESULTS

Patients with pHPT had an increased fracture incidence before surgery but not after pHPT surgery. Fracture incidence after surgery was inversely related to preoperative 24-hour urine calcium (incidence rate ratio for the highest tertile 220- mg/d 0.29, 95% confidence interval 0.11-0.73). Serum and 24-hour urine calcium, parathyroid hormone, osteocalcin, and adenoma weight were all associated with bone mineral density recovery after surgery.

CONCLUSION

Twenty-four-hour urine calcium is the most important biochemical variable to predict a decreased fracture incidence and improved bone mineral density after surgery for pHPT.

Weight gain after curative parathyroidectomy predicts increase in bone mineral density in patients with symptomatic primary hyperparathyroidism

BACKGROUND

Primary hyperparathyroidism (PHPT) results in reduction of bone mineral density (BMD) and an increased risk of pathological fractures. Curative surgery does improve BMD; however, the magnitude of rise and predictive factors are highly variable amongst the hitherto available studies.

OBJECTIVES

To quantify the magnitude of improvement in BMD after curative surgery in patients with symptomatic PHPT and dissect out the possible clinical and biochemical parameters predicting the BMD rise.

METHODS

We conducted a retrospective study of symptomatic PHPT patients undergoing surgery between August 2016 and July 2018. Patients achieving biochemical cure with pre- and post-operative (at least 1 year after surgery) dual-energy X-ray absorptiometry scans performed were included in the study.

RESULTS

After exclusion, 63 patients were included in the study (M:F = 2:5; mean age = 44.8 years). At a median interval of 15 months, the median per cent change in BMD (ΔBMD) at lumbar spine (LS), total hip (TH), femoral neck (FN) and one-third distal radius (forearm) was 6.5%, 7.0%, 8.1% and 6.9%, respectively. Following multiple linear regression analysis, baseline BMD was found to inversely predict ΔBMD at LS, TH and forearm. Pre-operative iPTH positively predicted ΔBMD at LS and FN. Interestingly, 82.5% of the patients had a gain in body weight following curative surgery and change in body weight emerged as a significant positive predictor of ΔBMD at all sites.

CONCLUSIONS

Curative surgery improves BMD at all sites in patients with symptomatic PHPT. Weight gain following surgery can be used as a positive clinical predictor of BMD rise.