Diameter of parathyroid glands measured by computed tomography as a predictive indicator for response to cinacalcet in dialysis patients with secondary hyperparathyroidism

Background/Aims: Cinacalcet is one of the important treatments of secondary hyperparathyroidism (SHPT). We evaluated the role of computed tomography (CT) for parathyroid glands (PTGs) to determine the response to cinacalcet therapy in dialysis patients. Methods: In study 1, we compared the predictive cutoff values of the largest volume or diameter of PTGs on ultrasonography or CT for achievement of target intact parathyroid hormone (iPTH) level according to K/DOQI guideline after cinacalcet treatment in a single dialysis center. In study 2, the role of the cutoff diameter of PTGs on CT in predicting responsive to cinacalcet therapy was reevaluated in dialysis patients with SHPT in multiple centers. Results: In study 1, among the total population of 26 patients, the number of patients with baseline iPTH over 600 pg/mL was 16 (61%). In study 2, it was 45 (54%), among 82 patients. In study 1, the number of PTGs equal to or larger than the cutoff value (≥ 11.2 mm) on CT, not ultrasonography, was significantly higher in non-responders than in responders (p=0.038). In study 2, the proportion of patients with PTGs ≥ 11.2 mm on CT was significantly higher in non-responders than responders (p=0.003). Multivariate analysis showed that pretreatment iPTH (odds ratio [OR] 1.498, p=0.003) and the existence of enlarged PTGs on CT (OR 8.940, p=0.015) were significant clinical factors affecting the response to cinacalcet. Conclusions: The diameter of PTGs on CT could predict the response to cinacalcet in dialysis patients with SHPT.