Glomerular filtration rate is associated with free triiodothyronine in euthyroid subjects: Comparison between various equations to estimate renal function and creatinine clearance

Free triiodothyronine to free thyroxine ratio as a marker of poor prognosis in euthyroid patients with acute coronary syndrome and diabetes after percutaneous coronary intervention

Objectives

In recent years, the free triiodothyronine/free thyroxine (FT3/FT4) ratio, a new comprehensive index for evaluating thyroid function, which could reflect thyroid function more stably and truly than serum thyroid hormone level, has been demonstrated to correlate with the risks of diabetes and cardiovascular disease in euthyroid adults. However, the correlation between thyroid hormone sensitivity and long-term prognosis in euthyroid patients with acute coronary syndrome (ACS) and diabetes after percutaneous coronary intervention (PCI) remains unclear.

Methods

A total of 1,786 euthyroid patients with ACS who successfully underwent PCI at Beijing Anzhen Hospital from August 2021 to April 2022 were included in our study, which was divided into three groups according to tertiles of thyroid hormone sensitivity index. Cox regression, Kaplan-Meier, and receiver operating characteristic analyses were applied to analyze the associations between the FT3/FT4 ratio with ACS and diabetes after PCI.

Results

Our analysis indicated that a lower level of FT3/FT4 ratio in euthyroid patients with acute coronary syndrome (ACS) and diabetes after PCI showed significantly higher incidences of major adverse cardiac and cerebrovascular events (MACCE) when compared with a higher level of FT3/FT4 ratio. After adjusting for other covariates, patients with a lower level of FT3/FT4 ratio were negatively associated with the risk of MACCE than those with a higher level of FT3/FT4 ratio (adjusted OR =1.61, 95% CI 1.05-2.47, P = 0.028). In subgroup analyses, individuals were stratified by age, sex, BMI, ACS type, hypertension, and dyslipidemia, showing that there were no significant interactions between the FT3/FT4 ratio and all subgroups for MACCE. In addition, the FT3/FT4 ratio performed better on ROC analyses for cardiac death prediction [area under the curve (AUC), 0.738].

Conclusion

A reduced level of FT3/FT4 ratio was a potential marker of poor prognosis in euthyroid patients with ACS and diabetes after PCI.

The Association Between Thyroid Hormones and Renal Function in Euthyroid Chinese Individuals: A Population-Based Cross-Sectional Study

Objective This population-based cross-sectional study aimed to investigate the association between thyroid hormones and renal function in euthyroid Chinese individuals, as the relationship between thyroid hormones and renal function in this population remains unclear. Methods A total of 661 participants were included in the study after excluding individuals with thyroid diseases, incomplete clinical measurements, or those taking medications affecting thyroid function. Participants were categorized into three groups based on serum thyroid hormone and antibody levels. The study adjusted for covariates and assessed the glomerular filtration rate (GFR) and urine albumin-to-creatinine ratio (ACR) in relation to thyroid hormone levels. Results After adjusting for covariates, the study found a significant increase in GFR in the middle and highest tertiles of free triiodothyronine (FT3) and the highest tertile of total triiodothyronine (TT3). Serum FT3 and TT3 levels were significantly associated with GFR. Additionally, the study observed a significantly lower GFR in the highest tertile of thyroid-stimulating hormone (TSH) compared to the lowest tertile. However, thyroid hormone and antibody levels were not associated with the ACR. Furthermore, the highest tertiles of TT3 and total thyroxine (TT4) were associated with a decreased risk of chronic kidney disease (CKD). Conclusion In our study among euthyroid Chinese individuals, we observed a significant association between thyroid function and GFR. Specifically, lower FT3, TT3, and higher TSH were associated with reduced GFR, indicating a potential role for thyroid hormones in maintaining renal function. Furthermore, lower levels of TT3 and TT4 were associated with an increased risk of CKD. These findings suggest a direct link between thyroid and renal function, even in euthyroid individuals, emphasizing the need for further investigation to elucidate the underlying mechanisms and potential therapeutic implications.

Higher Free Triiodothyronine Is Associated With Higher HDL Particle Concentration and Smaller HDL Particle Size

CONTEXT

Thyroid function status has effects on the development of atherosclerotic cardiovascular disease by affecting lipid metabolism, but associations of high-density lipoprotein (HDL) particle concentrations and subfractions with thyroid hormone levels within the reference range remain elusive.

OBJECTIVE

The aim of the present study was to determine the associations of free triiodothyronine (FT3), free thyroxine (FT4) and thyroid-stimulating hormone (TSH) levels with HDL particle characteristics in euthyroid individuals.

METHODS

This cross-sectional study on the associations of thyroid hormones with HDL particle concentrations, HDL subfractions, and HDL particle size included 5844 euthyroid individuals (FT3, FT4, and TSH levels within the reference range and no medication use affecting thyroid function), participating in the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) study. HDL particles and subfractions were measured by nuclear magnetic resonance using an optimized version of the NMR LipoProfile Test (LP4).

RESULTS

In multivariable linear regression analyses, FT3 was positively associated with total HDL particle concentration (std.β = 0.14; P < 0.001) and with small (std.β = 0.13; P < 0.001) and medium-sized HDL particles (std.β = 0.05; P = 0.001). Conversely, FT3 was inversely associated with large HDL particles (std.β = -0.07; P < 0.001) and with HDL particle size (std.β = -0.08; P < 0.001). Such associations with FT4 or reciprocally with TSH were less pronounced or nonsignificant.

CONCLUSION

In euthyroid individuals, higher FT3 is cross-sectionally associated with higher total HDL particle concentration and with lower HDL particle size. These associations may be relevant to better understand the role of HDL in thyroid function-associated atherosclerotic cardiovascular disease.

Associations among Ratio of Free Triiodothyronine to Free Thyroxine, Chronic Kidney Disease, and Subclinical Hypothyroidism

The ratio of free triiodothyronine (FT3) to free thyroxine (FT4) (FT3/FT4), a maker of peripheral thyroxin deiodination, could indicate activity of thyroid hormone. Since positive association between subclinical hypothyroidism (SCH) and chronic kidney disease (CKD) was reported, clarifying the association among FT3/FT4, SCH, and CKD could be an efficient tool to make a strategy for preventing CKD. A cross-sectional study with 1724 Japanese with normal thyroid hormone was conducted. Significant positive association between SCH and CKD was observed; the adjusted odds ratio (OR) and 95% confidence interval (95% CI) was 2.23 (1.38, 3.59). Even though, FT3/FT4 was found to be inversely associated with CKD whereas positively associated with SCH; the adjusted ORs and 95% CIs for 1 standard deviation (SD) increment of FT3/FT4 were 0.51 (0.35, 0.74) for CKD and 2.40 (1.34, 4.29) for SCH, respectively. FT3/FT4 was also found to be positively associated with SCH without CKD but not those with CKD; 1 SD increment of FT3/FT4 were 3.44 (1.72, 6.91) for SCH without CKD and 1.11 (0.40, 3.06) for SCH with CKD, respectively. Although further investigation is necessary, present study indicates that higher activity of peripheral thyroxin deiodination might have beneficial association on absence of CKD even among SCH which is positively associated with CKD.

Relationship Between Sporadic Renal Cysts and Renal Function Detected by Isotope Renography in Type 2 Diabetes

PURPOSE

This study aimed to reveal the relationship between the volume of sporadic renal cysts and renal function in patients with type 2 diabetes (T2D).

MATERIALS AND METHODS

One hundred and seventy-one patients that underwent renal imaging and other routine examinations at the Shanghai Pudong Hospital were included in this study. The Gates' method of glomerular filtration rate (GFR) was measured by ^99mTc-DTPA renal dynamic imaging in addition to the eGFR, calculated by the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI).

RESULTS

Our results showed that BMI, total iGFR, and eGFR showed significant differences between patients with T2D with or without SRC (p < 0.05). Spearman correlation analysis showed that cyst volume was positively correlated with Scr and gender but not iGFR (p > 0.05). The total iGFR positively correlated with eGFR (r = 0.83, p < 0.0001) and negatively with Scr (r = -0.78, p < 0.0001), age (r = -0.43, p < 0.0001), duration of T2D (r = -0.25, p = 0.001), and BMI (r = -0.21, p = 0.006) but not gender (r = -0.03, p = 0.668). The multilinear regression model revealed that gender (β = 0.346, p < 0.001), iGFR (β = -0.705, p < 0.001), and serum uric acid (β = 0.195, p = 0.032) were independent predictors of Scr. Moreover, we observed a significant increase in Scr in males (p < 0.05). Finally, we found that the split kidney function reflected by iGFR and related parameters such as time to peak (PTT) and half time of excretion (excrete t1/2) did not mutually distinguish from each other significantly whether they are measured in patients with renal cysts or in those without renal cysts (p > 0.05).

CONCLUSION

Our preliminary results suggest that in T2D, SRCs may be a renal complication of diabetic nephropathy. Although we found that the patients with renal cysts may display reduced iGFR, the volume of simple cysts seems not to exacerbate renal insufficiency. Isotope renography is a useful tool to evaluate the split kidney functions in diabetic patients who acquire single-side cysts.

Thyroid Feedback Quantile-based Index correlates strongly to renal function in euthyroid individuals

BACKGROUND

Previous studies have reported a negative relationship between thyroid-stimulating hormone (TSH) and renal function in euthyroid individuals, but others have found that higher free thyroxine (FT4) was associated with an increased risk of chronic kidney disease. This study was designed to analyze the relationship between thyroid and renal function from a new perspective of sensitivity to thyroid hormone.

METHODS

This retrospective study included 2831 euthyroid individuals who underwent a health examination at the First Hospital of China Medical University between January 2017 and December 2018. Parametric Thyroid Feedback Quantile-based Index (PTFQIFT4), TSH index (TSHI), thyrotroph T4 resistance index (TT4RI), free triiodothyronine to FT4 ratio (FT3/FT4), the secretory capacity of the thyroid gland (SPINA-GT) and the sum activity of peripheral deiodinases (SPINA-GD) were calculated. We also innovated the TT3RI and PTFQIFT3 indices based on FT3 and TSH. Renal function was assessed by estimated glomerular filtration rate (eGFR) CKD-EPI and creatinine-cystatin C-KDIGO equations.

RESULTS

After adjustment of basic characteristics and comorbidities, linear regression showed that eGFR CKD-EPI was positively associated with FT3/FT4 (β = 23.31), and inversely correlated to PTFQI FT4 (β= -2.69) (both p < .001). When comparing the fourth versus the first quartile of PTFQI FT4, the odds ratio (OR) for a reduced renal function was 1.89 (95% CI 1.28-2.80), and the OR was 0.64 (95% CI 0.43-0.95) when comparing quartiles of FT3/FT4 (both pfor trend< .05). In addition, for every 1SD increase in PTFQI FT4, the OR for a reduced renal function was 1.27 (95%CI 1.10-1.47). TSHI, TT4RI and TT3RI also showed a negative correlation to renal function. Similar results were obtained in SPINA-GD as in FT3/FT4.

CONCLUSIONS

In euthyroid individuals, decreased sensitivity to thyroid hormone is associated with reduced renal function. The composite PTFQIFT4 index correlates more strongly to renal function than TSH or T4 alone.KEY MESSAGESDecreased sensitivity to thyroid hormone is associated with reduced renal function in the euthyroid population.The recently developed composite index PTFQIFT4 seems to correlate more strongly to renal function than individual TSH or FT4 parameters.Innovative indices TT3RI and PTFQIFT3 based on the interaction between T3 and TSH may also reflect sensitivity to thyroid hormone.

[About connection of clinical manifestations of glomerulonephritis with features of the thyroid status of patients]

BACKGROUND

There are four clinical variants of glomerulonephritis (GN) - urinary (latent), hypertensive, nephrotic and mixed. It was found that the features of clinical manifestations of GN that determine its clinical variant do not depend on the etiology, pathogenesis and morphological form of the disease. Taking into account the obtained data on the association of nephrotic syndrome with hypofunction of the thyroid gland, we suggested, that the formation of clinical variants of GN may be influenced by the features of the thyroid status of patients.

AIM

Study the relationship of variants of clinical manifestations of GN with indicants of thyroid status.

MATERIALS AND METHODS

The study included patients with primary GN who received in-treatment in the nephrology unit of a general hospital. Patients were selected into 4 groups depending on the clinical variant of GN (urinary, nephrotic, hypertensive and mixed variants). When selecting patients, we achieved comparability of groups by age, gender, morphological variants and duration of the disease. In addition to the generally accepted methods of research, patients were performed: 1) assessment of the thyroid status (thyroid-stimulating hormone (TSH), free thyroxine (free T4), free triiodothyronine (free T3), antibodies to thyroperoxidase (anti-TPO), (free T3+free T4)/TSH, free T4/free T3, free T4/TSH); 2) determination of levels of interleukin - IL-1&beta;, IL-4 and IL-10 in blood serum; 3) ultrasound (US) examination of the thyroid gland. The obtained data were compared with those of healthy people.

RESULTS

The group of patients with the nephrotic variant of GN in 50% of cases showed a decrease of the level of free Т4 with the increase of TSH level, 26.7% showed a moderate increase of TSH at unchanged concentrations of free Т4 and free T3. In patients with the urinary variant of GN, the thyroid status did not differ from that in healthy patients, and the cytokine profile was characterized by a simultaneous increase in the content of the proinflammatory cytokine IL-1&beta; and the anti-inflammatory cytokine IL-10. The group of patients with the hypertonic variant of GN in 82% of cases showed an isolated increase in TSH content. In the group of patients with a mixed variant of GN, changes in thyroid indices were predominant, combined with a large variability in the level of IL-1&beta; production.

CONCLUSIONS

The results of the study indicate the influence of the functional state of the pituitary-thyroid system on the formation of different clinical variants of GN, which depends mainly on the level of production of the anti-inflammatory cytokine IL-10.

Fine particulate matter exposure and renal function: A population-based study among pregnant women in China

BACKGROUND

Fine particulate matter (PM_2.5) is the most serious environmental threat worldwide. The nephrotoxicity of PM_2.5 has been demonstrated in older adults, but no study has addressed the impacts of PM_2.5 exposure on renal function in pregnant women, who are recognized to be vulnerable and susceptible to PM_2.5 exposure.

OBJECTIVE

To evaluate whether exposures to PM_2.5 total mass and its chemical constituents were associated with reduced renal function among pregnant women in China.

METHODS

We measured serum concentrations of urea nitrogen (UN), uric acid (UA) and creatinine for 10,052 pregnant women in Shanghai, China. Exposures to PM_2.5 total mass and its 5 key chemical constituents during the whole pregnancy and each trimester of pregnancy was represented by satellite-based models.

RESULTS

Exposures to PM_2.5 total mass and its chemical constituents of organic matter (OM), black carbon (BC), nitrate (NO₃^-) and ammonium (NH₄⁺) were positively associated with serum levels of UN and UA, and negatively associated with estimated glomerular filtration rate (eGFR). An interquartile rang (IQR) increase in PM_2.5 total mass, OM, BC, NO₃^- and NH₄⁺ exposure in third trimester was associated with 1.33 (β = -1.33, 95% CI, -1.79, -0.87), 1.67 (β = -1.67, 95% CI, -2.26, -1.07), 1.29 (β = -1.29, 95% CI,-1.89, -0.70), 1.16 (β = -1.16, 95% CI,-1.66, -0.65) and 0.76 (β = -0.76, 95% CI, -1.08, -0.44) mL/min/1.73 m² decrease in eGFR, respectively.

CONCLUSION

We concluded that exposures to PM_2.5 during pregnancy were associated with decreased renal function among pregnant women.

Subclinical hypothyroidism is associated with albuminuria in Japanese nondiabetic subjects

PURPOSE

Thyroid dysfunction is a risk factor of cardiovascular disease (CVD), and albuminuria is a predictor of CVD. For preventing the CVD, it is essential to clarify from which stage of thyroid dysfunction the risk of CVD starts developing. We thus investigated the association between subclinical thyroid dysfunction and albuminuria, focusing on a nondiabetic general population.

METHODS

We analyzed the data of 17,221 nondiabetic subjects who underwent annual health checkups by multivariate logistic regression analyses.

RESULTS

Compared with the subjects with euthyroidism, those with subclinical hypothyroidism presented a higher prevalence of albuminuria. By a multivariate logistic regression analysis, subclinical hypothyroidism showed a significant and independent association with the high prevalence of albuminuria compared with euthyroidism (OR 1.64, 95% CI 1.21-2.21, p = 0.001). In accord with this result, the analysis in which the lowest quartile of thyroid stimulating hormone (TSH) concentration (<0.96 µIU/mL) was used as a reference revealed that the highest quartile (>2.07 µIU/mL) had a significant and independent association with the prevalence of albuminuria (OR 1.23, 95% CI 1.01-1.51, p = 0.04). One microliter unit per milliliter increase of the serum concentration of TSH also had a significant and independent association with the prevalence of albuminuria (OR 1.07, 95% CI 1.02-1.12, p = 0.006). The association between subclinical hyperthyroidism and the prevalence of albuminuria was not significant.

CONCLUSION

Our data indicated that subclinical hypothyroidism was significantly and independently associated with the high prevalence of albuminuria.

Relationship between Thyroid and Kidney Function: Analysis from the Korea National Health and Nutrition Examination Survey Between 2013 and 2015

INTRODUCTION

Thyroid function is evaluated by thyroid stimulating hormone (TSH) and free thyroxine (fT4). Although many studies have indicated an intimate relationship between thyroid hormones and kidney functions, reports about the simultaneous evaluation of TSH and fT4 are rare.

OBJECTIVE

We aimed to analyze the association between TSH and kidney function, with emphasis on a potential nonlinear relationship, and identify an independent relationship between fT4 and kidney function.

METHODS

We reviewed the data of 7,061 subjects in the Korea National Health and Nutrition Examination Surveys who were randomly subsampled for thyroid function evaluation between 2013 and 2015. A total of 5,578 subjects were included in the final analysis, after excluding people <18 years old, and those with a short fasting time, abnormal fT4 levels, and thyroid disease or related medications. Creatinine-based estimated glomerular filtration rate (eGFR) was used to define kidney function.

RESULTS

A 1 mmol/L increase of logarithmic TSH was associated with decreased eGFR (β: -1.8; 95% CI -2.3 to -1.2; p < 0.001), according to multivariate linear regression analysis. On the multivariate generalized additive model plot, TSH demonstrated an L-shaped relationship with eGFR, showing a steeper slope for 0-4 mIU/L of TSH. A 1 µg/dL increase of fT4 was also associated with decreased eGFR (β: -7.0; 95% CI -0.94 to -4.7; p < 0.001) on the multivariate linear regression analysis; this association was reversed after adjusting for age. On the mediation analysis, the indirect effect via age and direct effect per 1 µg/dL increase of fT4 on eGFR was 9.9 (8.1 to 11.7, p < 0.001) and -7.1 (-9.3 to -4.8, p < 0.001), respectively.

CONCLUSIONS

Increased TSH was associated with decreased eGFR, particularly in the reference range. The direct effect of increased fT4 was decreased eGFR, which may be affected indirectly by age.

Low thyroid function is not associated with an accelerated deterioration in renal function

BACKGROUND

Chronic kidney disease (CKD) is frequently accompanied by thyroid hormone dysfunction. It is currently unclear whether these alterations are the cause or consequence of CKD. This study aimed at studying the effect of thyroid hormone alterations on renal function in cross-sectional and longitudinal analyses in individuals from all adult age groups.

METHODS

Individual participant data (IPD) from 16 independent cohorts having measured thyroid stimulating hormone, free thyroxine levels and creatinine levels were included. Thyroid hormone status was defined using clinical cut-off values. Estimated glomerular filtration rates (eGFR) were calculated by means of the four-variable Modification of Diet in Renal Disease (MDRD) formula. For this IPD meta-analysis, eGFR at baseline and eGFR change during follow-up were computed by fitting linear regression models and linear mixed models in each cohort separately. Effect estimates were pooled using random effects models.

RESULTS

A total of 72 856 individuals from 16 different cohorts were included. At baseline, individuals with overt hypothyroidism (n = 704) and subclinical hypothyroidism (n = 3356) had a average (95% confidence interval) -4.07 (-6.37 to -1.78) and -2.40 (-3.78 to -1.02) mL/min/1.73 m2 lower eGFR as compared with euthyroid subjects (n = 66 542). In (subclinical) hyperthyroid subjects (n = 2254), average eGFR was 3.01 (1.50-4.52) mL/min/1.73 m2 higher. During 329 713 patient years of follow-up, eGFR did not decline more rapidly in individuals with low thyroid function compared with individuals with normal thyroid function.

CONCLUSIONS

Low thyroid function is not associated with a deterioration of renal function. The cross-sectional association may be explained by renal dysfunction causing thyroid hormone alterations.

Fluoride exposure and kidney and liver function among adolescents in the United States: NHANES, 2013-2016

BACKGROUND

Hepato- and nephrotoxicity of fluoride have been demonstrated in animals, but few studies have examined potential effects in humans. This population-based study examines the relationship between chronic low-level fluoride exposure and kidney and liver function among United States (U.S.) adolescents. This study aimed to evaluate whether greater fluoride exposure is associated with altered kidney and liver parameters among U.S. youth.

METHODS

This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (2013-2016). We analyzed data from 1983 and 1742 adolescents who had plasma and water fluoride measures respectively and did not have kidney disease. Fluoride was measured in plasma and household tap water. Kidney parameters included estimated glomerular filtration rate (calculated by the original Schwartz formula), serum uric acid, and the urinary albumin to creatinine ratio. Liver parameters were assessed in serum and included alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, blood urea nitrogen, gamma-glutamyl transferase, and albumin. Survey-weighted linear regression examined relationships between fluoride exposure and kidney and liver parameters after covariate adjustment. A Holm-Bonferroni correction accounted for multiple comparisons.

RESULTS

The average age of adolescents was 15.4 years. Median water and plasma fluoride concentrations were 0.48 mg/L and 0.33 μmol/L respectively. A 1 μmol/L increase in plasma fluoride was associated with a 10.36 mL/min/1.73 m2 lower estimated glomerular filtration rate (95% CI: -17.50, -3.22; p = 0.05), a 0.29 mg/dL higher serum uric acid concentration (95% CI: 0.09, 0.50; p = 0.05), and a 1.29 mg/dL lower blood urea nitrogen concentration (95%CI: -1.87, -0.70; p < 0.001). A 1 mg/L increase in water fluoride was associated with a 0.93 mg/dL lower blood urea nitrogen concentration (95% CI: -1.44, -0.42; p = 0.007).

CONCLUSIONS

Fluoride exposure may contribute to complex changes in kidney and liver related parameters among U.S. adolescents. As the study is cross-sectional, reverse causality cannot be ruled out; therefore, altered kidney and/or liver function may impact bodily fluoride absorption and metabolic processes.

Negative association between free triiodothyronine level and contrast-induced acute kidney injury in patients undergoing primary percutaneous coronary intervention

BACKGROUND

A low FT3 level is significantly associated with a variety of kidney disease and acute myocardial infarction (AMI). However, it remains unclear whether low FT3 is associated with CI-AKI in patients who underwent pPCI.

METHODS

Single-center retrospective study evaluated 363 STEMI patients undergoing pPCI. Patients were classfied into 2 groups, low FT3 group (FT3 < 3.1 pmol/L) and normal FT3 group (FT3 ≥ 3.1 pmol/L);CI-AKI was defined as an increase in the serum creatinine levels of ≥50% or 0.3 mg/dL above the baseline level within 48 h after contrast medium exposure.

RESULTS

Overall, 80(22.0%) patients had low FT3, and 59(16.3%) patients developed CI-AKI. The incidence of CI-AKI and in-hospital mortality was significantly higher in patients with low FT3 than normal (31.3% vs 12.0%; 15.0% vs 3.2%, respectively, both p < 0.0001). Multivariate logistic regression analysis indicated that low FT3 was an independent predictor of CI-AKI (odds ratio [OR] = 2.62, 95%CI:1.35-5.07, p < 0.05). In addition, low FT3 was associated with an increased risk of all-cause mortality during a mean follow-up period of 20 months (hazard ratio [HR] = 2.54, 95%CI:1.15-5.60, p < 0.05).

CONCLUSION

Low FT3 was associated with CI-AKI, short- and long-term mortality in STEMI patients after pPCI.