Population Study On The Relationship Between Thyroid Hormone And Renal Function

Objective: To explore the relationship between thyroid hormone level and renal function in the general population and to provide new ideas for diagnosing and treating chronic kidney disease(CKD)and thyroid disease.Methods: This research data was based on an ongoing population study on multiple cardiovascular risk factors in Dali,Yunnan Province.After excluding participants with thyroid diseases,incomplete clinical measurements,or taking medications such as amiodarone,which affect thyroid function,661 subjects were included in the present analysis.Of the participants,421(63.7%)were women,209(31.6%)had hypertension,and 72(10.9%)had diabetes mellitus.The thyroid function of participants and renal function,including glomerular filtration rate(GFR),urine albumin to creatinine ratio(ACR),and other indicators,were measured and calculated.We classified the participants into three groups according to the tertiles of serum thyroid hormone and antibody levels.The thyroid hormone and antibody levels were treated as categorical and continuous variables.Before and after adjusting for covariates such as age,sex,body mass index(BMI),current smoking,alcohol intake,diabetes mellitus,hypertension,and antihypertensive treatment,multiple linear regression was used to analyze the relationship between thyroid function and GFR and ACR,respectively.Binary logistic regression was used to analyze the relationship between thyroid function and CKD.Results1.In this natural population,current smoking,alcohol intake,hypertension,diabetes mellitus,and CKD were more common in men(P≤0.049).In addition,men in this study were older and had a higher BMI,triglycerides,low-density lipoprotein cholesterol(LDL-C),serum creatinine,systolic blood pressure,and diastolic blood pressure than women(P≤0.029).Compared with women,men had lower GFR and lower levels of high-density lipoprotein cholesterol(HDL-C),total triiodothyronine(TT3),thyroid stimulating hormone(TSH),thyroglobulin antibody(TGAb)(P≤0.031).2.After adjusting for covariates,when thyroid hormone and antibody levels were analyzed as categorical variables,compared with those of the lowest tertile of free triiodothyronine(FT3),the GFRs of the middle and highest tertiles of FT3 were higher,and with the increase in FT3 tertiles,GFR also increased significantly(middle: β=3.21,95%CI: 0.19,6.24,P=0.0377;highest: β=5.49,95%CI: 2.48,8.50,P=0.0004).The GFR of the highest tertile of TT3 was 5.15 higher than that of the lowest tertile(95% CI: 2.13,8.17,P=0.0009).The GFR of the highest tertile of TSH was 4.09 lower than that of the lowest tertile(95%CI:-7.21,-0.98,P=0.0103).When thyroid hormone and antibody levels were analyzed as continuous variables,serum FT3(β=2.23,95%CI: 0.96,3.50,P=0.0006)and TT3(β=7.58,95%CI: 3.74,11.42,P=0.0001)were significantly and positively associated with GFR.3.Before adjusting for covariates,when thyroid hormone and antibody levels were analyzed as categorical variables,the ACR of the highest tertile of free thyroxine(FT4)was 16.82 higher than that of the lowest tertile(95%CI: 1.49,32.15,P=0.0319).When thyroid hormone and antibody levels were analyzed as continuous variables,FT4 was significantly and positively correlated with ACR(β=1.62,95%CI: 0.07,3.17,P=0.0406).After adjusting for covariates,there was no significant difference between thyroid hormone and antibody levels and ACR(P≥0.1005).4.After adjusting for covariates,the highest tertile of TT3 levels was associated with a 95% decreased risk of CKD compared with the lowest tertile of TT3(OR=0.05,95%CI: 0.01,0.48,P=0.0091).Compared with the lowest tertile of total thyroxine(TT4),the highest tertile of TT4 was associated with a 76% lower risk of CKD(OR=0.24,95%CI: 0.07,0.85,P=0.0271).Conclusion: Lower thyroid function was associated with decreased GFR and increased risk of CKD in the natural population without obvious thyroid dysfunction.The measurement of thyroid function had important clinical value in the diagnosis,treatment,and prediction of CKD.