Association between body mass index and multigland primary hyperparathyroidism.

INTRODUCTION

Multigland disease (MGD) accounts for 15% of sporadic primary hyperparathyroidism (pHPT). Several studies have reported a link between obesity and calcium metabolism (e.g., increased incidence of pHPT, higher levels of parathyroid hormone, lower vitamin D levels, and larger parathyroid glands). Obese patients have also been shown to require reoperation for persistent/recurrent pHPT more often than nonobese controls. We hypothesize that obese patients may have a higher prevalence of MGD.

METHODS

This was a retrospective review of a prospectively collected parathyroid database that included adult patients with sporadic pHPT, who underwent initial parathyroidectomy between 1999 and 2013. Demographic, clinicopathologic, operative, and laboratory data were assessed for associations with MGD.

RESULTS

Of 1305 consecutive patients, 200 (15%) had MGD. Median age was 59 y. Univariate analyses demonstrated that MGD was associated with age > 60 y, higher body mass index (BMI), history of lithium therapy, lower 24-h urine calcium excretion, higher serum alkaline phosphatase levels, and smaller size of the first excised parathyroid gland. On multivariate analyses, predictors of MGD were BMI 30-39.9 kg/m(2) (odds ratio [OR] 1.5; 95% confidence interval [CI] 1.2-2.5), BMI ≥ 40 kg/m(2) (OR 1.8; 95% CI 1.3-3.1), and smaller size of the first excised parathyroid (OR 0.7; 95% CI 0.6-0.8).

CONCLUSIONS

This study demonstrates a higher incidence of MGD in obese and morbidly obese patients. Due to a higher risk of MGD, surgeons should have a lower threshold to perform bilateral exploration in obese patients, especially if the first excised parathyroid gland is relatively small.