The association of thyroid parameters with markers of chronic kidney disease in euthyroid patients with type 2...

This study was established to explore the association of thyroid parameters including thyroid hormone and thyroid sensitivity indices with chronic kidney disease (CKD) in euthyroid patients with type 2 diabetes (T2D). CKD markers were defined by estimated glomerular filtration rate (eGFR) based on serum creatinine (Scr) (eGFRcr), eGFR based on cystatin C (cys C) (eGFRcys), and urinary albumin-to-creatinine ratio (UACR). Thyroid parameters, including triiodothyronine (FT3), free thyroxin (FT4), thyroid-stimulating hormone (TSH), FT3/FT4 ratio, TSH index (TSHI), and thyrotroph T4 resistance index (TT4RI), were measured. The prevalence rates of CKD defined by eGFRcys, eGFRcr, and UACR was 19.9%, 14.1%, and 50.6%, respectively. The eGFRcys and eGFRcr levels increased with increasing FT3 and FT3/FT4 tertiles, while the UACR levels increased with decreasing FT3 tertiles. Spearman's analysis demonstrated that FT3 and FT3/FT4 were positively associated with eGFRcys and eGFRcr, and negatively associated with UACR. In logistic regression analyses, compared with the lowest FT3 tertile (≤4.12 pmol/L), the adjusted ORs for CKD (eGFRcys <60 mL/min/1.73 m²) in the middle FT3 tertile (4.12-4.74 pmol/L) and higher FT3 tertile (>4.74 pmol/L) were 0.248 and 0.153, respectively, but prominent associations of thyroid parameters with eGRFcr <60 mL/min/1.73 m² and UACR were not observed after adjustment. Linear regression analysis demonstrated that eGFRcys was more strongly associated with FT3 than eGFRcr or UACR in the adjusted model. Among euthyroid patients with T2D, FT3 in the normal range was the independent factor most strongly related to CKD. Additionally, eGFRcys rather than eGFRcr or UACR was the CKD marker most associated with FT3.