FREE THYROID HORMONES AND MORTALITY IN CAUCASIANS UNDERGOING ANGIOGRAPHY: THE LUDWIGSHAFEN RISK AND CARDIOVASCULAR HEALTH (LURIC) STUDY

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.

Chronic Methylmercury Intoxication Induces Systemic Inflammation, Behavioral, and Hippocampal Amino Acid Changes in C57BL6J Adult Mice

Methylmercury (MeHg) is highly toxic to the human brain. Although much is known about MeHg neurotoxic effects, less is known about how chronic MeHg affects hippocampal amino acids and other neurochemical markers in adult mice. In this study, we evaluated the MeHg effects on systemic lipids and inflammation, hippocampal oxidative stress, amino acid levels, neuroinflammation, and behavior in adult male mice. Challenged mice received MeHg in drinking water (2 mg/L) for 30 days. We assessed weight gain, total plasma cholesterol (TC), triglycerides (TG), endotoxin, and TNF levels. Hippocampal myeloperoxidase (MPO), malondialdehyde (MDA), acetylcholinesterase (AChE), amino acid levels, and cytokine transcripts were evaluated. Mice underwent open field, object recognition, Y, and Barnes maze tests. MeHg-intoxicated mice had higher weight gain and increased the TG and TC plasma levels. Elevated circulating TNF and LPS confirmed systemic inflammation. Higher levels of MPO and MDA and a reduction in IL-4 transcripts were found in the hippocampus. MeHg-intoxication led to increased GABA and glycine, reduced hippocampal taurine levels, delayed acquisition in the Barnes maze, and poor locomotor activity. No significant changes were found in AChE activity and object recognition. Altogether, our findings highlight chronic MeHg-induced effects that may have long-term mental health consequences in prolonged exposed human populations.

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.

Correlation between inflammatory parameters and pituitary-thyroid axis in patients with COVID-19

PURPOSE

Inflammation plays a critical role in the progression of COVID-19. Nonthyroidal illness syndrome (NTIS) has been increasingly recognized in affected patients. We aim to evaluate the correlation of thyroid hormones with markers of inflammation and association with disease outcome in hospitalized patients with COVID-19, and in two profiles of NTIS (low T3-normal/low FT4 vs. low T3-high FT4).

METHODS

consecutive patients admitted to a nonintensive care unit for COVID-19 were recruited. Infection was mild in 22%, moderate in 27.1% and severe in 50.8%; 7.41% died. T4, T3, FT4, FT3, and their ratios (T3/T4, FT3/FT4) were correlated with albumin, ferritin, fibrinogen, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), lactate dehydrogenase (LDH), and D-dimer.

RESULTS

Fifty five patients (50.9% men, median age 56 years) were included. Albumin correlated positively with T3 and hormones ratios, but negatively with FT4. T3, FT3, T3/T4, and FT3/FT4 correlated inversely with ferritin, fibrinogen, ESR, CRP, LDH, and D-dimer. FT4 showed direct correlation with fibrinogen and ESR. T3/T4 was lower in severe compared to mild/moderate disease [7.5 (4.5-15.5) vs. 9.2 (5.8-18.1); p = 0.04], and lower in patients who died than in those discharged [5 (4.53-5.6) vs. 8.1 (4.7-18.1); p = 0.03]. A low T3/high FT4 profile was associated with lower albumin, higher ferritin, and severity.

CONCLUSION

In this cohort, thyroid hormones correlated with inflammation and outcome. T3 and T3/T4 correlated inversely with inflammatory markers; a low T3/T4 ratio was associated with severity and poor prognosis. Patients with low T3 but high FT4 had higher ferritin, lower albumin, and more severe disease at presentation.

The significance of high thyroxine in hospitalized patients with low thyroid-stimulating hormone

PURPOSE

There is scarce data about the interpretation of high thyroid hormone levels in hospitalized patients. We wished to investigate the significance of high thyroxine (T4) in hospitalized patients with low TSH.

METHODS

We conducted a retrospective study of data from patients in nonsurgical departments. Three groups of random patients with low TSH were defined and compared: 123 patients with only high FT4 levels (T4 group), 82 with high FT3 levels with or without high FT4 level (T3 group), and 119 with low FT3 and FT4 level in the lower half of the norm and below (NTIS group).

RESULTS

The primary cause of admission in the T4 and NTIS groups was infectious disease, 20.3% and 40.3%, respectively; while in the T3 group it was cardiovascular disease (31.7%). The T4 group but not T3 group had epidemiological and clinical characteristics similar to the NTIS group. The T4 group had a significant correlation between increased CRP levels and decreased FT3 (r = 0.366, p < 0.001) similar to the NTIS group. The T3 group had a borderline correlation between increased FT3 and FT4 levels (r = 0.208, p = 0.061) but the T4 group did not.

CONCLUSIONS

The combination of low TSH and high FT4 levels in hospitalized patient is usually caused by nonthyroidal illness combined with drug effects. This thyroid function disturbance is common in hospitalized patients and if the FT3 level is below the middle of the norm, treatment is probably unnecessary.

Predictive value of free triiodothyronine (FT3) to free thyroxine (FT4) ratio in long-term outcomes of euthyroid patients with three-vessel coronary artery disease

BACKGROUND AND AIMS

Whether routine assessment of FT3/FT4 ratio in euthyroid patients with three-vessel disease (3VD) could help identify high-risk individuals remains unclear. This study evaluated the relationship between FT3/FT4 ratio and long-term clinical outcomes in this specific population.

METHODS AND RESULTS

This study included 2106 euthyroid patients with 3VD (stenoses of ≥50% in right coronary artery, left circumflex and left anterior descending). Patients were categorized into three groups according to tertiles of FT3/FT4 ratio (Q1>2.58,n = 704; 2.2 ≤ Q2<2.58, n = 706; Q3<2.22, n = 696). The median follow-up time was 5.3 years, during which 206 deaths and 332 MACCEs (consisting of all-cause death, myocardial infarction, and stroke) occurred. Compared with the other two groups, patients with low level of FT3/FT4 ratio tended to be female, older, diabetic, and had significantly higher incidences of all-cause death, cardiac death and MACCE (all P < 0.05). Cox regression analysis showed that patients with low level of FT3/FT4 ratio had higher risks of long-term cardiac death (adjusted HR = 1.87, 95% CI 1.06-3.28, P = 0.030) and MACCE (adjusted HR = 1.43, 95% CI 1.07-1.93, P = 0.017) than those with high level of FT3/FT4 ratio. Subgroup analysis showed there was a significant interaction between FT3/FT4 ratio and age (≥65 years vs.<65 years) for MACCE (P = 0.029).

CONCLUSION

Low level of FT3/FT4 ratio is independently associated with an increased risk of long-term cardiac death and MACCE in euthyroid patients with 3VD. Routine assessment of FT3/FT4 ratio might be helpful to identify high-risk individuals in this specific population.

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

BACKGROUND

In euthyroid patients undergoing percutaneous coronary intervention (PCI), it is still unclear whether free triiodothyronine to free thyroxine (FT3/FT4) ratio can predict the recurrence of cardiovascular events (CVEs). We aim to investigate its association with recurrent long-term adverse events in this population.

METHODS

3549 euthyroid patients with prior CVEs history undergoing PCI were consecutively enrolled in our study and subsequently divided into three FT3/FT4 ratio tertiles (T1<2.41, n=1170; 2.41≤T2<2.75, n=1198; T3>2.75, n=1181). The primary endpoint was major adverse cardiovascular and cerebrovascular event (MACCE), a composite of all-cause death, myocardial infarction, stroke and revascularization. The secondary endpoints were all-cause death and cardiac death.

RESULTS

The median follow-up time was 5 years. The incidence of all-cause death, cardiac death and MACCE were significantly higher among patients in the lowest FT3/FT4 tertile (P<0.05). After adjustment of confounding factors, decreased FT3/FT4 ratio was independently associated with an increased risk of all-cause death (HR 1.82, 95% CI 1.13-2.93, P=0.014), cardiac death (HR 1.90, 95% CI 1.04-3.46, P=0.036) and MACCE (HR 1.33, 95% CI 1.10-1.60, P=0.003) which was driven mainly by all-cause death.

CONCLUSIONS

In euthyroid patients with prior cardiovascular events undergoing PCI, FT3/FT4 ratio might be a potential predictor of all-cause and cardiac mortality. Routine assessment of FT3/FT4 ratio might be a simple and effective tool for risk stratification in this specific patient population.

Associations of Thyroid Hormones and Resting Heart Rate in Patients Referred to Coronary Angiography

Resting heart rate (RHR) is associated with increased risk of cardiovascular morbidity and mortality. Thyroid hormones exert several effects on the cardiovascular system, but the relation between thyroid function and RHR remains to be further established. We evaluated whether measures of thyroid hormone status are associated with RHR in patients referred to coronary angiography. Thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxin (FT4), and RHR were determined in 2795 participants of the Ludwigshafen Risk and Cardiovascular Health (LURIC) Study. Median (25th to 75th percentile) serum concentrations were 1.25 (0.76-1.92) mU/l for TSH, 4.8 (4.2-5.3) pmol/l for FT3 and 17.1 (15.4-19.0) pmol/l for FT4, and mean (±standard deviation) RHR was 68.8 (±11.7) beats/min. Comparing the highest versus the lowest quartile, RHR (beats/min) was significantly higher in the fourth FT4 quartile [3.48, 95% confidence interval (CI): 2.23-4.73; p <0.001] and in the fourth FT3 quartile (2.30, 95% CI: 1.06-3.55; p <0.001), but there was no significant difference for TSH quartiles. In multiple linear regression analyses adjusting for various potential confounders, FT3 and FT4 were significant predictors of RHR (p <0.001 for both). In subgroups restricted to TSH, FT3, and FT4 values within the reference range, both FT3 and FT4 remained significant predictors of RHR (p <0.001 for all). In conclusion, in patients referred to coronary angiography, FT3 and FT4 but not TSH were positively associated with RHR. The relationship between free thyroid hormones and RHR warrants further investigations regarding its diagnostic and therapeutic implications.

Prognostic significance of high free T4 and low free T3 levels in non-thyroidal illness syndrome

BACKGROUND

Non-thyroidal illness syndrome is characterized by decreased serum free T3 (FT3) level and associates with long term mortality. Serum free T4 (FT4) may affect on mortality with FT3 in course of chronic illness. This study performed to evaluate the association between both decreased FT3 with elevated FT4 levels and mortality risk.

METHODS

This study is a retrospective cohort analysis and consisted up 1164 (571 male, 593 female) patients with a 36 months follow up period. Patients divided into four groups according to thyroid functions. Patients with euthyroidism were in Group A, elevated FT3 in group B, decreased FT3 in group C and both decreased FT3 and elevated FT4 levels in group D. The levels of thyroid hormones and all cause mortality were compared between four groups.

RESULTS

Mortality rate was elevated between Groups A and B, A and C, A and D, B and C, B and D, C and D, (p < .001, p < .001, p < .001, p < .001, p < .001, p:0.019, respectively). A multivariate Cox proportional hazards model was performed to evaluate the mortality risk between groups. A close relationship was observed in Group C and D patients for the mortality risk (OR:1.561, 95% CI:1.165-2.090, p:0.003 and OR:2.224, 95% CI:1.645-3.006, p:0.0001, respectively).

CONCLUSION

Both decreased FT3 and elevated FT4 levels are independent predictor for long term mortality risk in hospitalized chronic patients with non-thyroidal illness syndrome.