Thyroid-Stimulating Hormone and Estimated Glomerular Filtration Rate

Background: Hypothyroidism has been identified as a comorbidity related to chronic kidney disease (CKD). The retrospective study investigated thyroid function and CKD, and assessed the relationship between thyroid-stimulating hormone (TSH) and urine albumin/creatinine ratio (ACR), and the slope of estimated glomerular filtration rate (eGFR), stratified by CKD grades. Methods: This retrospective cohort study was conducted in a community nephrology clinic established with clinical and demographic data, from April 1, 2015 until December 30, 2019. Hypothyroidism prevalence, eGFR slope and ACR were the outcomes of interest and were analyzed by using unconditional and adjusted generalized linear model (GLM) and logistic regression model. Results: Of the 312 subjects, 58.3% were male, 12.8% had hypothyroidism, and 43.3% had diabetes mellitus, with the median age of 73 years (interquartile range (IQR): 29 - 99). The hypothyroidism prevalence was 9.4%, 11.5%, 15%, and 17.5% for the CKD categories defined as grade 1 and 2 combined, grade 3, grade 4, and grade 5, respectively. The overall median eGFR slope was -0.0027 (IQR: -0.158 - 0.602). With GLM models, the adjusted odds ratio of 1.052 (95% confidence interval (CI): 1.006 - 1.100) was calculated for TSH level > 5 mu IU/L (Q2), per unit mL/min/day decline in eGFR slope. The overall median urine ACR was 10.2 mg/mmol (IQR: 0.24 - 1,414). In a GLM model with urine ACR per unit mg/mmol, the adjusted odds ratio of TSH level of > 1.8 mu IU/LM (50th percentile) was 1.02 (95% CI: 1.01 - 1.23). Conclusions: The prevalence of hypothyroidism increased with worsening eGFR grades from 9.4% to 17.4% at baseline. The higher TSH levels were associated with faster decline in eGFR and higher levels of albuminuria. Furthermore, prospective studies are needed to evaluate the effect of hypothyroidism treated on renal function.