Abstract
Background/Objectives: Secondary hyperparathyroidism (SHPT) is a common and clinically significant complication of advanced chronic kidney disease and may require surgical intervention when medical therapy fails. This study aimed to evaluate the association between parathyroid gland burden, defined by gland number and size parameters, and biochemical disease severity in patients undergoing parathyroidectomy for SHPT, and to assess the concordance between preoperative imaging findings and intraoperative observations. Although parathyroid gland enlargement is a hallmark of SHPT, the clinical relevance of parathyroid gland number and overall gland burden in relation to biochemical disease severity and the accuracy of preoperative imaging remains incompletely defined. Methods: This single-center, retrospective observational study included adult patients who underwent parathyroidectomy for secondary hyperparathyroidism between January 2015 and December 2020. Demographic, clinical, laboratory, imaging, intraoperative, and histopathological data were analyzed. Parathyroid gland burden was assessed based on gland number, largest gland diameter, and total gland burden. Associations between gland morphology and biochemical parameters were evaluated using correlation analyses and multivariable logistic regression. Agreement between preoperative imaging and intraoperative findings was assessed using diagnostic performance metrics, contingency analysis, and the weighted kappa coefficient. Results: A total of 101 patients were included. Patients with three or more enlarged parathyroid glands had significantly higher preoperative parathyroid hormone and alkaline phosphatase levels, higher serum phosphorus levels, and lower calcium and vitamin D levels (all p < 0.05). Total gland burden and largest gland diameter were positively correlated with parathyroid hormone and alkaline phosphatase levels. In multivariable analysis, higher parathyroid hormone levels, longer dialysis duration, and vitamin D deficiency were independently associated with high gland burden. Preoperative imaging demonstrated moderate agreement with intraoperative findings (weighted kappa = 0.46; 95% CI, 0.29-0.63). Separate evaluation of imaging modalities showed that both ultrasonography and scintigraphy had relatively high sensitivity but limited specificity for detecting extensive gland involvement. Conclusions: In patients undergoing parathyroidectomy for secondary hyperparathyroidism, increased parathyroid gland burden is associated with greater biochemical disease severity. Preoperative imaging shows limited concordance with intraoperative findings and should be interpreted cautiously, particularly in the presence of multiglandular disease. These findings support the integration of morphological parameters into comprehensive preoperative assessment while highlighting the need for larger prospective, multicenter studies with standardized imaging protocols and long-term follow-up.