Usefulness of FT3 to FT4 Ratio to Predict Mortality in Euthyroid Patients With Prior Cardiovascular Events Undergoing PCI: Five-Year Findings From a Large Single-Center Cohort Study

J-shaped association of free triiodothyronine to free thyroxine ratio with 5-year mortality among patients with chronic kidney disease: a prospective cohort study

PURPOSE

To investigate the association of free triiodothyronine to free thyroxine (FT3/FT4) ratio with 5-year mortality in patients with chronic kidney disease (CKD) using data from the National Health and Nutrition Examination Survey (NHANES) through 2001-2002 and 2007-2012.

METHODS

Two thousand four hundred twenty-four patients with CKD stage 1-5 were included. Patients' baseline characteristics were collected. Cox proportional hazards models were used to investigate the association of FT3/FT4 ratio with 5-year all-cause and cardiovascular mortality. Subgroup analysis was performed.

RESULTS

Within 5 years of follow-up duration, 425 (17.53%) deaths were recorded, and 154 patients died from cardiovascular disease. A J-shaped association between FT3/FT4 ratio and 5-year mortality was observed. After fully adjustment, the elevated FT3/FT4 ratio was significantly associated with a decreased 5-year all-cause mortality risk (HR: 0.79, 95% CI 0.63-0.99) among patients with CKD stage 1-5 when FT3/FT4 ratio < 4.71, and is significantly associated with an increased 5-year all-cause mortality risk in CKD patients with advanced CKD stages or low UACR when FT3/FT4 ratio ≥ 4.71 (HR: 2.74, 95% CI 1.20-6.29; HR: 3.09, 95% CI 1.12-8.57, respectively). The elevated FT3/FT4 ratio also showed a J-shaped association with the 5-year cardiovascular mortality which disappears after fully adjustment.

CONCLUSION

The FT3/FT4 ratio is closely associated with 5-year mortality risk among patients with CKD, indicating a potential role of FT3/FT4 ratio as a biomarker for mortality prediction in CKD patients.

Association between sensitivity to thyroid hormones and dyslipidemia in patients with coronary heart disease

BACKGROUND

Thyroid hormones affect lipid metabolism via central and peripheral regulation. However, there have been few studies on the association between thyroid hormone sensitivity and dyslipidemia. We aimed to investigate the association between thyroid hormone sensitivity and dyslipidemia in patients with coronary heart disease (CHD).

METHODS

A total of 31,678 patients with CHD were included in this large multicenter retrospective study. Central thyroid hormone sensitivity was evaluated using the thyroid feedback quantile-based index (TFQI), parametric thyroid feedback quantile-based index (PTFQI), thyroid-stimulating hormone index (TSHI), and thyrotropin thyroxine resistance index (TT4RI); peripheral thyroid hormone sensitivity was assessed by the ratio of free triiodothyronine (FT3)/free thyroxine (FT4). Logistic regression analysis was used to analyze the association between thyroid hormone sensitivity and dyslipidemia.

RESULTS

Among 31,678 participants, 21,648 (68.34%) had dyslipidemia. In the multi-adjusted models, the risk of dyslipidemia was positively correlated with TFQI (odds ratio [OR]: 1.04; 95% confidence interval [CI]: 1.03-1.05), PTFQI (OR: 1.09; 95% CI: 1.06-1.12), TSHI (OR: 1.08; 95% CI: 1.06-1.11), and TT4RI (OR: 1.08; 95% CI: 1.05-1.11). Conversely, the risk of dyslipidemia was negatively correlated with FT3/FT4 (OR: 0.94; 95% CI: 0.92-0.97). In stratified analyses, the association between thyroid hormone sensitivity and dyslipidemia was statistically significant for different sexes, glucose levels, and blood pressure states.

CONCLUSION

There is a significant association between sensitivity to thyroid hormones and dyslipidemia, regardless of sex, glucose level, or blood pressure. Graphical abstract.

Low FT3/FT4 Ratio Is Linked to Poor Prognosis of Acute Myocardial Infarction in Euthyroid Patients with Type 2 Diabetes Mellitus

This is an observational, retrospective, single-center study aimed to determine whether the free triiodothyronine (FT3) to free thyroxine (FT4) ratio was related to acute myocardial infarction (AMI) prognosis in individuals with type 2 diabetes mellitus (T2DM). A total of 294 euthyroid T2DM patients with new-onset AMI were enrolled. FT3/FT4 ratio tertiles were used to categorize patients into Group 1 (FT3/FT4 ≥ 4.3), Group 2 (3.5 ≤ FT3/FT4 < 4.3), and Group 3 (FT3/FT4 < 3.5). Major adverse cardiac events (MACE), including nonfatal myocardial infarction, target vessel revascularization (TVR), and cardiac mortality, served as the primary endpoint. Group 3 demonstrated a considerably higher incidence of MACE than the other two groups over the average follow-up duration of 21 ± 6.5 months (all p < 0.001). Multivariable Cox regression analysis showed that a low FT3/FT4 ratio was an independent risk factor for MACE after AMI (Group 1 as a reference; Group 2: hazard ratio [HR] 1.275, 95% confidence interval [CI]: 0.563−2.889, p = 0.561; Group 3: HR 2.456, 95% CI: 1.105−5.459, p = 0.027). Moreover, the area under the receiver-operating characteristic curve (AUC) indicates a good predictive value of FT3/FT4 ratio for MACE (AUC = 0.70). Therefore, in T2DM patients with AMI, a low FT3/FT4 ratio was strongly linked to poor prognosis.

Association of thyroid function, within the euthyroid range, with cardiovascular risk: The EPIPorto study

BACKGROUND

Thyroid hormones are important modulators of cardiovascular function. Both hypothyroidism and hyperthyroidism are known to contribute to an increased cardiovascular risk. It remains uncertain whether thyroid hormones level within the euthyroid range are associated with cardiometabolic risk. We aimed to evaluate the association between thyroid function levels within the euthyroid range and cardiovascular risk in a population-based cohort.

METHODS

Eight hundred thirty-five subjects aged ≥45 years from the EPIPorto population-based cohort were included. We excluded participants with TSH, free T4 (FT4), or free T3 (FT3) outside of the reference range, or with previous cardiovascular or thyroid disease. The associations between thyroid function, cardiovascular risk factors and the 10-year estimated risk of cardiovascular events (using SCORE2 and SCORE2-OP) were evaluated in linear and logistic regression models, crudely and adjusting for age, sex, BMI, diabetes, and smoking.

RESULTS

The mean age of the participants was 61.5 (SD 10.5) years and 38.9% were men. Eleven percent of the participants had diabetes, 47.8% had dyslipidemia, and 54.8% had hypertension. The mean body mass index (BMI) was 27.4 (SD 4.6) kg/m², and the median (percentile25-75) 10-year risk of cardiovascular events was 5.46% (2.92, 10.11). Participants with higher BMI, larger waist circumference and higher hs-CRP had higher levels of FT3 and FT3/FT4 ratio. Lower FT3/FT4 ratio and higher FT4 levels were associated with higher prevalence of diabetes and more adverse lipid profile. Higher TSH, lower FT3 and lower FT3/FT4 ratio were associated with lower eGFR. Lower FT3, lower FT3/FT4 ratio and higher FT4 were associated with an increased 10-year risk of cardiovascular events.

CONCLUSIONS

In a population-based study, variations of thyroid function within the euthyroid range were associated with cardiovascular risk factors. On one hand, individuals with higher BMI, larger waist circumference and higher hs-CRP had higher levels of FT3 and FT3/FT4 ratio. On the other hand, a decreased conversion of T4 to T3 (lower FT3, lower FT3/FT4 ratio and/or higher FT4) was associated with a higher prevalence of diabetes, a more adverse lipid profile, a lower eGFR and an increased 10-year risk of cardiovascular events.

Free Triiodothyronine and Free Triiodothyronine to Free Thyroxine Ratio Predict All-Cause Mortality in Patients with Diabetic Foot Ulcers

PURPOSE

Free triiodothyronine (FT3) and FT3/free thyroxine (FT4) ratio have been associated with mortality in various diseases. However, no study to date has identified a link between FT3, FT3/FT4 ratio and all-cause mortality in patients with diabetic foot ulcers (DFUs). This study aimed to investigate this relationship.

METHODS

This retrospective cohort study included 726 patients diagnosed with DFUs in a public hospital from January 2015 to October 2019. Patients were classified by the optimal cut-off values of the FT3 and FT3/FT4 ratio, respectively. The association of FT3 and FT3/FT4 ratio with all-cause mortality was evaluated in a multivariable cox regression model. Directed acyclic graphs were used to assess the minimally sufficient sets of confounding variables.

RESULTS

Log rank tests indicated that patients with low FT3 and FT3/FT4 ratio had lower overall survival rates (all p < 0.001). The adjusted HRs for all-cause mortality were 0.48 (95% CI: 0.32-0.73, P = 0.001) when comparing high versus low FT3 and 0.47 (95% CI: 0.32-0.70, P < 0.001) when comparing high versus low FT3/FT4 ratio. Subgroup analyses showed that these associations existed only in elderly patients (≥65 years) and women, after adjustment. In men, only high FT3/FT4 ratio was associated with low all-cause mortality, after adjustment.

CONCLUSION

Routine assessment of FT3 and FT3/FT4 ratio may be a simple and effective way to identify high-risk patients with DFUs, especially in elderly patients and women.

FT3/FT4 ratio is correlated with all-cause mortality, cardiovascular mortality, and cardiovascular disease risk: NHANES 2007-2012

BACKGROUND

Thyroid hormones play a vital role in maintaining the homeostasis of the cardiovascular system. The FT3/FT4 ratio can be used to evaluate the rate of T4-to-T3 conversion, reflecting the peripheral sensitivity of thyroid hormones. There is no study to investigate its relationship with death and cardiovascular disease (CVD) in the general population.

METHODS

This retrospective cohort study involved 8,018 participants with measured thyroid function and no prior thyroid disease who participated in the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2012. Mortality status was determined by routine follow-up using the National Death Index through December 31, 2015.

RESULTS

During a median of 87 months of follow-up, we observed 699 all-cause deaths, including 116 cardiovascular deaths. In multivariate adjusted models, higher free thyroxine (FT4) was linked to increased all-cause mortality (HR, 1.15 per SD; 95% CI, 1.09-1.22), cardiovascular mortality (HR, 1.18 per SD; 95% CI, 1.01-1.39), and CVD risk (HR, 1.17 per SD; 95% CI, 1.08-1.27). Higher free triiodothyronine (FT3) was linked to decreased all-cause mortality (HR 0.81 per SD; 95% CI, 0.70-0.93). Higher FT3/FT4 ratio was linked to decreased all-cause mortality (HR, 0.77 per SD; 95% CI, 0.69-0.85), cardiovascular mortality (HR, 0.79 per SD; 95% CI, 0.62-1.00), and CVD risk (HR, 0.82 per SD; 95% CI, 0.74-0.92). The FT3/FT4 ratio stratified findings were broadly consistent with the overall results.

CONCLUSIONS

FT3, FT4, and the FT3/FT4 ratio were all independent predictors of all-cause death. FT4 and the FT3/FT4 ratio, but not FT3, were independent predictors of cardiovascular mortality and CVD risk. Along with FT3 and FT4, we should pay equal attention to the FT3/FT4 ratio in the general population.

Impaired sensitivity to thyroid hormones and carotid plaque in patients with coronary heart disease: A RCSCD-TCM study in China

CONTEXT

Previous studies on the association between thyroid function and carotid plaque have shown contradictory results, which may be attributable to the sensitivity to thyroid hormone indices. This study aimed to analyze the association between thyroid hormone sensitivity and risk of carotid plaque in patients with coronary heart disease (CHD) and further explore this association according to sex, age, smoking, and drinking status.

METHODS

This large-scale, multi-center, retrospective, cross-sectional study included 6679 patients with CHD (age 35-75). Central sensitivity to thyroid hormone was evaluated by the thyroid feedback quantile-based index (TFQI), parametric thyroid feedback quantile-based index (PTFQI), thyroid-stimulating hormone index (TSHI), and thyrotroph thyroxine resistance index (TT4RI). Peripheral sensitivity to thyroid hormone was assessed by free triiodothyronine/free thyroxine (FT3/FT4) ratio. Taking no carotid plaque as a reference, this study used logistic regression to analyze the association between central and peripheral thyroid hormone sensitivity and carotid plaque in patients with CHD.

RESULTS

Of the 6679 patients with CHD, 4843 (72.50%) had carotid plaque. In the multi-adjusted models, the TFQI (odds ratio [OR]: 1.50; 95% confidence interval [CI]: 1.26-1.78; P < 0.001), PTFQI (OR: 1.76; 95% CI: 1.46-2.12; P < 0.001), TSHI (OR: 1.21; 95% CI: 1.10-1.33; P < 0.001), and TT4RI (OR: 1.00; 95% CI: 1.00-1.01; P = 0.003) were positively associated with the risk of carotid plaque. Compared with that in females and people > 60 years, the OR value for carotid plaque was higher in males and people ≤ 60 years. Similarly, smokers and drinkers had higher OR values for carotid plaque than non-smokers and non-drinkers. Conversely, FT3/FT4 ratio (OR: 0.75; 95% CI: 0.70-0.81; P < 0.001) was negatively associated with carotid plaque, and the OR value for carotid plaque was lower in males, patients ≤ 60 years, smokers, and drinkers.

CONCLUSION

This study showed that thyroid hormone sensitivity is significantly associated with carotid plaque in patients with CHD. This association is more significant in males, patients ≤ 60 years, smokers, and drinkers.

FT4/FT3 ratio: A novel biomarker predicts coronary microvascular dysfunction (CMD) in euthyroid INOCA patients

BACKGROUND

Ischemia and no obstructive coronary artery disease (INOCA) patients who presented coronary microvascular dysfunction (CMD) demonstrate a poor prognosis, yet the risk factors for CMD remain unclear. Subtle changes in thyroid hormone levels within the normal range, especially the free thyroxine (FT4)/free triiodothyronine (FT3) ratio, have been shown to regulate the cardiovascular system. This prospective study investigated the correlation between FT4/FT3 ratio and CMD in euthyroid patients with INOCA.

METHODS

This prospective study (www.chictr.org.cn/, ChiCTR2000037112) recruited patients with myocardial ischemia symptoms who underwent both coronary angiography (CAG) and myocardial perfusion imaging (MPI) with dynamic single-photon emission computed tomography (D-SPECT). INOCA was defined as coronary stenosis< 50% and CMD was defined as coronary flow reserve (CFR)<2.5. All patients were excluded from abnormal thyroid function and thyroid disease history.

RESULTS

Among 71 INOCA patients (15 [21.1%] CMD), FT4 and FT4/FT3 ratio in CMD group were significantly higher and both showed significantly moderate correlation with CFR (r=-0.25, p=0.03; r=-0.34, p=0.003, respectively). The ROC curve revealed that FT4/FT3 ratio had the highest efficacy for predicting CMD with an optimized cutoff value>3.39 (AUC 0.78, p<0.001, sensitivity, 80.0%; specificity, 71.4%). Multivariate logistic regression showed that FT4/FT3 ratio was an independent predictor of CMD (OR 7.62, 95% CI 1.12-51.89, p=0.038, P for trend=0.006).

CONCLUSION

In euthyroid INOCA patients, increased FT4/FT3 ratio levels are associated with the occurrence of CMD, presenting a novel biomarker for improving the risk stratification.

Free triiodothyronine levels and age influences the metabolic profile and COVID-19 severity parameters in euthyroid and levothyroxine-treated patients

Metabolic reprogramming is required to fight infections and thyroid hormones are key regulators of metabolism. We have analyzed in hospitalized COVID-19 patients: 40 euthyroid and 39 levothyroxine (LT4)-treated patients in the ward and 29 euthyroid and 9 LT4-treated patients in the intensive care unit (ICU), the baseline characteristics, laboratory data, thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), the FT3/FT4 ratio, 11 antiviral cytokines and 74 metabolomic parameters. No evidence for significant differences between euthyroid and LT4-treated patients were found in the biochemical, metabolomic and cytokines parameters analyzed. Only TSH (p=0.009) and ferritin (p=0.031) showed significant differences between euthyroid and LT4-treated patients in the ward, and TSH (p=0.044) and FT4 (p=0.012) in the ICU. Accordingly, severity and mortality were similar in euthyroid and LT4-treated patients. On the other hand, FT3 was negatively related to age (p=0.012), independently of sex and body mass index in hospitalized COVID-19 patients. Patients with low FT3 and older age showed a worse prognosis and higher levels of the COVID-19 severity markers IL-6 and IL-10 than patients with high FT3. IL-6 negatively correlated with FT3 (p=0.023) independently of age, body mass index and sex, whereas IL-10 positively associated with age (p=0.035) independently of FT3, body mass index and sex. A metabolomic cluster of 6 parameters defined low FT3 ward patients. Two parameters, esterified cholesterol (p=4.1x10^-4) and small HDL particles (p=6.0x10^-5) correlated with FT3 independently of age, body mass index and sex, whereas 3-hydroxybutyrate (p=0.010), acetone (p=0.076), creatinine (p=0.017) and high-density-lipoprotein (HDL) diameter (p=8.3x10^-3) were associated to FT3 and also to age, with p-values of 0.030, 0.026, 0.017 and 8.3x10^-3, respectively. In conclusion, no significant differences in FT3, cytokines, and metabolomic profile, or in severity and outcome of COVID-19, were found during hospitalization between euthyroid patients and hypothyroid patients treated with LT4. In addition, FT3 and age negatively correlate in COVID-19 patients and parameters that predict poor prognosis were associated with low FT3, and/or with age. A metabolomic cluster indicative of a high ketogenic profile defines non-critical hospitalized patients with low FT3 levels.