Chronic Kidney Disease and Thyroid Hormones

CONTEXT: Thyroid dysfunction is prevalent in chronic kidney disease (CKD) patients and significantly impacts renal outcomes and mortality. OBJECTIVE: This study investigated the associations between thyroid function and clinical outcomes, and also the therapeutic effects of thyroid hormone replacement therapy (THRT) in CKD patients. METHODS: We conducted a retrospective cohort study using data from the China Renal Data System. The primary endpoints were composite renal failure and all-cause mortality. The secondary endpoint was the impact of THRT on renal outcomes. Associations were analyzed using multivariable Cox proportional hazards regression models and Kaplan-Meier survival analyses, with adjustment for relevant clinical and demographic covariates. RESULTS: Among 30 804 CKD patients enrolled, 26 673 (86.6%) had normal thyroid function, 2291 (7.4%) had hypothyroidism, and 1840 (6.0%) had hyperthyroidism. Hypothyroidism independently predicted increased risk of renal failure (adjusted HR = 1.29; 95% CI, 1.15-1.45; P < .001). Both hypothyroidism (adjusted HR = 1.24; 95% CI, 1.11-1.39; P < .001) and hyperthyroidism (adjusted HR = 1.20; 95% CI, 1.07-1.33; P < .01) were associated with increased all-cause mortality. Notably, THRT was associated with significantly reduced risk of renal failure (adjusted HR = 0.65; 95% CI, 0.52-0.82; P < .001) in hypothyroid patients. CONCLUSION: This large-scale cohort study demonstrates that hypothyroidism accelerates CKD progression, while both hypo- and hyperthyroidism increase mortality risk in CKD patients. THRT appears to attenuate the adverse effects of hypothyroidism on renal function. Regular thyroid function monitoring and appropriate THRT should be considered in CKD management.