Preservation of Renal Function by Thyroid Hormone Replacement Therapy in Chronic Kidney Disease Patients with Subclinical Hypothyroidism

Context: Subclinical hypothyroidism is not a rare condition, but the use of thyroid hormone to treat subclinical hypothyroidism is an issue of debate. Objective: This study was undertaken to investigate the impact of thyroid hormone therapy on the changes in estimated glomerular filtration rate (eGFR) in subclinical hypothyroidism patients with stage 2-4 chronic kidney disease. Patients: A total of 309 patients were included in the final analysis. Main Outcome Measure: The changes in eGFR over time were compared between patients with and without thyroid hormone replacement therapy using a linear mixed model. Kaplan-Meier curves were constructed to determine the effect of thyroid hormone on renal outcome, a reduction of eGFR by 50%, or end-stage renal disease. The independent prognostic value of subclinical hypothyroidism treatment for renal outcome was ascertained by multivariate Cox regression analysis. Results: Among the 309 patients, 180 (58.3%) took thyroid hormone (treatment group), whereas 129 (41.7%) did not (nontreatment group). During the mean follow-up duration of 34.8 +/- 24.3 months, the overall rate of decline in eGFR was significantly greater in the nontreatment group compared to the treatment group (-5.93 +/- 1.65 vs. -2.11 +/- 1.12 ml/min/yr/1.73 m(2); P = 0.04). Moreover, a linear mixed model revealed that there was a significant difference in the rates of eGFR decline over time between the two groups (P < 0.01). Kaplan-Meier analysis also showed that renal event-free survival was significantly lower in the nontreatment group (P < 0.01). In multivariate Cox regression analysis, thyroid hormone replacement therapy was found to be an independent predictor of renal outcome (hazard ratio, 0.28; 95% CI, 0.12-0.68; P = 0.01). Conclusion: Thyroid hormone therapy not only preserved renal function better, but was also an independent predictor of renal outcome in chronic kidney disease patients with subclinical hypothyroidism. (J Clin Endocrinol Metab 97: 2732-2740, 2012)