The Correlation Between Low Serum T3 Levels and All-Cause and Cardiovascular Mortality in Peritoneal Dialysis Patients

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 serum-free thyroxine level and all-cause mortality in critically ill patients: a retrospective study from MIMIC-IV

Background

Low thyroxine (T4) levels have been observed in critically ill patients; however, controversial results regarding T4 supplemental therapy are reported. The association between serum free T4 (FT4) levels and mortality in critically ill patients has not been fully established and needs to be clarified.

Methods

Data from the Medical Information Mart for Intensive Care (MIMIC)-IV were collected and analyzed. The association between FT4 level and 30-day mortality after ICU admission was analyzed using Kaplan-Meier curves, spline smoothing fitting, martingale residuals of the null Cox model, and restricted cubic spline (RCS). Logistic regression, Cox regression, and receiver operating characteristic curve (ROC) were used to uncover the relationship and predictive value of serum FT4 and 30-day mortality in critically ill patients.

Results

In the final analysis, 888 patients were enrolled, and the serum FT4 levels were divided into four groups. A significant difference in 30-day mortality was observed between the four groups. Kaplan-Meier curves also presented significantly higher 30-day mortality in groups 1 and 2 (p < 0.0001). Further multivariance logistic regression showed that group 1 with FT4 levels lower than 0.7 μg/dl can predict 30-day mortality (odds ratio (OR) = 3.30, 95% confidence interval (CI) = 1.04-11.31). Spline smoothing fitting analysis showed a "V"-shaped line between 30-day mortality and FT4 level within 0-3 μg/dl. Further RCS analysis showed that the risk of death decreased rapidly as FT4 levels increased when serum FT4 levels were lower than 1.2 μg/dl and started to become flat afterward. The area under the ROC of the lower FT4 level to predict 30-day mortality was 0.833 (95% CI = 0.788-0.878). Both multivariant Cox regression and logistic regression showed that FT4 levels lower than 1.2 μg/dl can independently predict 30-day mortality when adjusted for other potential confounders (HR = 0.34, 95% CI = 0.14-0.82; OR = 0.21, 95% CI = 0.06-0.79, respectively), but its predictive power disappeared when adjusted for T3 or total T4.

Conclusion

Serum FT4 levels were significantly negatively associated with 30-day mortality when they were lower than 1.2 μg/dl and could predict the risk of 30-day mortality. A higher FT4 level is potentially related to increased 30-day mortality.

Thyroid Function and Low Free Triiodothyronine in Chinese Patients With Autoimmune Encephalitis

Background and Objectives

Low free triiodothyronine (FT3) is usually associated with worse functional outcome in critical illness; however, the information on thyroid dysfunction and autoimmune encephalitis (AE) is limited. This study aims to evaluate the clinical prognostic value of thyroid function and low-T3 syndrome in patients with multiple subtypes of AE.

Methods

In this retrospective study, we identified the hospital records of 319 candidate patients with AE admitted between January 2016 and December 2020. We then extracted the clinical features and outcomes. Modified Rankin scale (mRS) scores were used to evaluate the patients’ neurological function. The serum levels of FT3, free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were measured upon admission. Normal thyroid stimulating hormone level with FT3 below the lower limit of the reference interval (2.63 nmol/L) was defined as low-T3 syndrome.

Results

A total of 237 AE cases remained after screening. Among these, 57.81% (137/237) were men and the average age at onset was 41 y (interquartile range, 12–61 y). We found that 83.54% (198/237) of the patients had a good prognosis, and 16.46% (39/237) had a poor prognosis. Abnormal thyroid function was observed in 30.80% of these patients, with a relatively greater prevalence in the group with a poor prognosis (p < 0.001). The serum FT3 levels in the poor-prognosis group were significantly lower than those in the good-prognosis group (p < 0.001). Low-T3 syndrome occurred in 15.19% of AE cases and was more frequent in patients with poor prognosis (p < 0.001).

Conclusions

Abnormal thyroid function in AE is frequent, and serum FT3 levels in patients with poor prognosis are significantly lower than in those with good prognosis. Low-T3 syndrome could be a potential candidate for predicting the prognosis of AE following future research.

The serum free triiodothyronine to free thyroxine ratio as a potential prognostic biomarker of chronic kidney disease in patients with glomerular crescents: A retrospective study

BACKGROUND

Crescent formation indicates severe glomerular pathology, and hypothyroidism usually predicts poor prognosis for severe diseases. However, the relationship between thyroid function and the progression of chronic kidney disease (CKD) is unclear. This study analysed the prognostic predictive value of the serum free triiodothyronine (FT3) to free thyroxine (FT4) ratio and its correlation with renal function in patients with CKD with crescent formation.

METHODS

This single-centre study included 162 CKD patients with glomerular crescents confirmed by renal pathology between March 2012 and December 2014. According to the first tertile (0.284) of FT3/FT4 ratio, the patients were divided into high and low FT3/FT4 ratio groups. Kaplan-Meier and Cox regression analyses were performed to evaluate the prognostic value of the FT3/FT4 ratio.

RESULTS

The age, haemoglobin, eGFR, urinary albumin-to-creatinine ratio, cardiac troponin T, N-terminal brain natriuretic peptide precursor, FT3, FT4, percentage of total crescents in non-globally sclerotic glomeruli, prevalences of hypertension, moderate to severe renal tubulopathy and crescentic nephritis, and proportion of patients receiving glucocorticoids and immunosuppressants were significantly different between high and low FT3/FT4 ratio groups (P < 0.05). Multivariate Cox regression analysis showed that when compared with patients with a high FT3/FT4 ratio (>0.284), those with intermediate and low FT3/FT4 ratios (≤0.284) had an increased risk of the long-term composite endpoint (P < 0.05 for various adjustment models).

CONCLUSIONS

A low FT3/FT4 ratio is associated with increased mortality and worse outcome risk in CKD patients with crescent pathology.