Objective: We investigated the relationship between thyroid hormones and the risk of diabetic kidney disease (DKD) progression.
Methods: A total of 452 patients with type 2 diabetes were included, and a cross-sectional analysis was performed. Urine albumin/creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR) were used to diagnose persistent albuminuria and stage chronic kidney disease, respectively. The Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline was used to describe the risk of DKD progression (low, moderate, and high or very high risks).
Results: The DKD group had higher levels of thyroid-stimulating hormone (TSH) and lower levels of free triiodothyronine (FT₃) and free thyroxine (FT₄) than the non-DKD group. The prevalence of thyroid dysfunction in the DKD group was significantly higher than in the non-DKD group, especially the prevalence of subclinical hypothyroidism. FT₃ levels decreased gradually with the deterioration of DKD. TSH levels increased with an increasing KDIGO category. FT₃ and FT₄ levels were negatively correlated with serum creatinine levels and ACR, and positively correlated with eGFR. Contrastingly, TSH was positively correlated with ACR, and negatively correlated with eGFR. After adjustment, an increase in FT₃ levels significantly reduced the risk of DKD [odds ratio, OR (95% confidence interval, CI)=0.58 (0.42– 0.79)] and DKD progression [ORs (95% CIs)=0.65 (0.45– 0.93) for the moderate risk group and 0.50 (0.33– 0.74) for the high or very high-risk group, using the low-risk group as a reference]. FT₃ levels below 4.30 pmol/L in men and 3.99 pmol/L in women were the cut-off points for an increased risk of DKD progression.
Conclusion: Low FT₃ level is an independent risk factor for DKD and DKD progression. FT₃ ≤ 4.30 pmol/L in men and ≤ 3.99 pmol/L in women will greatly increase the risk of kidney disease progression in patients with type 2 diabetes.
Keywords: thyroid hormone, prognosis of chronic kidney disease, type 2 diabetes mellitus