J. A. Glenn1, T. W. Yen1, D. B. Evans1, T. S. Wang1 1Medical College Of Wisconsin,Division Of Surgical Oncology – Section Of Endocrine Surgery,Milwaukee, WI, USA
Introduction: Sporadic primary hyperparathyroidism (pHPT) is due to multi-gland disease (MGD) in up to 15% of cases. MGD may occur due to systemic disease and/or variations in the parathyroid hormone (PTH)-calcium-vitamin D axis. Vitamin D deficiency is more pronounced in obese patients due to sequestration of fat-soluble vitamins in adipose tissue. The aim of this study is to explore the relationship between obesity, vitamin D deficiency, and MGD.
Methods: This is a retrospective chart review of a prospective parathyroid database of 583 patients with sporadic pHPT who underwent parathyroidectomy between 1/1/2009 – 12/31/2013. Demographic, clinicopathological (number and weight of enlarged glands), and laboratory (serum calcium, PTH, 25-OH vitamin D, creatinine) data were collected. Patients were equally divided into 4 groups based on body mass index (BMI; kg/m2). The association between BMI and age, gender, race, perioperative vitamin D, PTH, and calcium levels were assessed. Multivariable logistic regression models were performed to determine clinicopathological predictors of MGD.
Results: Mean age of the cohort was 59.8 ± 12.0 years (range, 18-90); 463 (79%) were women, and 507 (87%) were Caucasian. Of these, 103 (18%) patients had MGD. Patients with a higher BMI tended to have higher preoperative PTH levels, although this was not statistically significant (Table 1). There was an association between BMI and vitamin D deficiency (<30 ng/mL, p<0.001). In unadjusted analyses, there was no association between BMI (Table 1), age, gender, or race and the occurrence of MGD. Of the 549 patients with recorded gland weights, the median gland weight was 470 mg (interquartile range, 240-923). There was no association between BMI and gland weight or vitamin D deficiency and gland weight in patients with MGD. On multivariate logistic regression, after adjusting for preoperative calcium and PTH levels, BMI and vitamin D levels were not predictors of MGD.
Conclusion: There is no association between obesity, vitamin D deficiency and occurrence of MGD in pHPT patients, in adjusted analyses. In addition, BMI and vitamin D deficiency are not associated with increased gland weight for MGD patients. Further studies evaluating the molecular influences of obesity and vitamin D deficiency on parathyroid tissue are needed to help clarify relationships between these factors and MGD.
