Increased Risk of Chronic Kidney Disease After Total Thyroidectomy: A Nationwide Matched Cohort Study

Background Development of hypoparathyroidism (hypoPT) after total thyroidectomy (TT) may increase the risk of kidney-related morbidity. We aimed to examine the risk of hypoPT and chronic kidney disease (CKD) in patients undergoing TT in Denmark over a 20-year period.Materials and Methods Using population-based registries, we identified all Danish individuals with TT between January 1998 and December 2017. We included a matched comparison cohort by randomly selecting 10 citizens for each patient by sex and birth year. We calculated the cumulative incidence and hazard ratio (HR) of CKD by Cox regression in patients with TT compared with the comparison cohort. Further, CKD risks were stratified by indications for TT and comorbidity groups according to the Charlson Comorbidity Index.Results We included 2421 patients with TT; 21.5% had hypoPT. After 10 years, the risk of developing CKD for hypoPT patients was 13.5% [95% confidence interval (CI): 9.8-17.7], 11.6% (95% CI: 9.7-13.7) for patients without hypoPT, and 5.8% (95% CI: 5.3-6.2) for the comparison cohort. When compared with the matched comparison cohort, the adjusted HR for CKD in hypoPT patients was 3.23 (95% CI: 2.37-4.41) and 2.27 (95% CI: 1.87-2.75) for patients without hypoPT. For patients without previous comorbidities, the adjusted HR of CKD was higher than in patients with several comorbidities.Conclusion HypoPT was a frequent complication after TT and was associated with an increased risk of CKD. We also found an increased risk of CKD in patients with a normal parathyroid function after TT, which needs to be further evaluated.