Thyroid hormones associate with risk of incident chronic kidney disease and rapid decline in renal function: a prospective investigation

BACKGROUND: Thyroid hormones have been associated with renal dysfunction in cross-sectional studies. However, prospective studies exploring the effect of thyroid hormones on renal function decline were sparse and got contradictive results. We aimed to prospectively explore the associations of thyroid hormones with incident chronic kidney disease (CKD) and rapid decline in estimated glomerular filtration rate (eGFR) in Chinese adults. METHODS: The participants were from a community-based cohort including 2103 individuals aged 40 years or above without CKD at baseline. Thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxin (FT4) were measured by radioimmunoassay at baseline. Serum creatinine, urinary creatinine and albumin were measured at baseline and follow-up. CKD was defined as eGFR <60 ml/min/1.73 m(2) or urinary albumin-to-creatinine ratio ≥30 mg/g. Rapid eGFR decline was defined as an annual eGFR decline >3 ml/min/1.73 m(2). RESULTS: During 4 years of follow-up, 198 participants developed CKD and 165 experienced rapid eGFR decline. Compared to tertile 1, tertile 3 of FT4 levels were associated with 1.88-folds (95% confidence interval [CI], 1.27–2.77) increased risk of incident CKD; and 1.64-folds (95% CI, 1.07–2.50) increased risk of rapid eGFR decline (both P for trend ≤0.02), after adjustment for confounders. Each 1-pmol/l of FT4 was associated with 12% increased risk of incident CKD and 10% of rapid eGFR decline. Among the incident CKD individuals, FT4 was significantly associated with higher risk of concurrent complications and further outcomes of CKD. We did not find associations of FT3 or TSH with CKD or rapid eGFR decline. CONCLUSIONS: Higher FT4, but not TSH and FT3, was associated with increased risk of incident CKD and rapid eGFR decline in middle-aged and elderly Chinese.