FT4 Levels Research Articles

Branched-Chain Amino Acids, Alanine, and Thyroid Function: A Cross-Sectional, Nuclear Magnetic Resonance (NMR)-Based Approach from ELSA-Brasil.

The association of thyroid function with essential and non-essential amino acids is understudied, despite their common metabolic roles. Thus, our aim was to evaluate the association of thyroid function with the levels of branched-chain amino acids (BCAAs-leucine, isoleucine, and valine) and of alanine in the general population. We utilized data from the São Paulo research center of ELSA-Brasil, a longitudinal population-based cohort study. Thyroid parameters included thyroid stimulating hormone (TSH), free T4 and free T3 levels, and the FT4:FT3 ratio. BCAAs and alanine were analyzed on a fully automated NMR platform. The current analysis included euthyroid participants and participants with subclinical hyperthyroidism and hypothyroidism. We used Pearson's coefficient to quantify the correlation between thyroid-related parameters and amino acids. Linear regression models were performed to analyze whether thyroid parameters were associated with BCAAs and alanine levels. We included 4098 participants (51.3 ± 9.0 years old, 51.5% women) in this study. In the most adjusted model, higher levels of TSH were associated with higher levels of alanine, FT4 levels were inversely associated with isoleucine levels, FT3 levels were statistically significant and positively associated with valine and leucine, and the T3:T4 ratio was positively associated with all amino acids. We observed that subclinical hypothyroidism was positively associated with isoleucine and alanine levels in all models, even after full adjustment. Our findings highlight the association of subclinical hypothyroidism and thyroid-related parameters (including TSH, free T4, free T3, and FT4:FT3 ratio) with BCAAs and alanine. Further studies are needed to explore the mechanisms underlying this association. These insights contribute to our understanding of the influence of thyroid-related parameters on BCAA and alanine metabolism.

Role of Lugol solution before total thyroidectomy for Graves' disease: randomized clinical trial.

Lugol solution is often administered to patients with Graves' disease before surgery. The aim is to reduce thyroid vascularization and surgical morbidity, but its real effectiveness remains controversial. The present study was designed to evaluate the effects of preoperative Lugol solution on thyroid vascularization and surgical morbidity in patients with Graves' disease undergoing total thyroidectomy. Fifty-six patients undergoing total thyroidectomy for Graves' disease were randomly assigned to receive 7 days of Lugol treatment (Lugol+ group, 29) or no Lugol treatment (LS- group, 27) before surgery in this single-centre and single-blinded trial. Preoperative hormone and colour Doppler ultrasonographic data for assessing thyroid vascularization were collected 8 days before surgery (T0) and on the day of surgery (T1). The primary outcome was intraoperative and postoperative blood loss. Secondary outcomes included duration of surgery, thyroid function, morbidity, vascularization, and microvessel density at final pathology. No differences in demographic, preoperative hormone or ultrasonographic data were found between LS+ and LS- groups at T0. At T1, free tri-iodothyronine (FT3) and free thyroxine (FT4) levels were significantly reduced compared with T0 values in the LS+ group, whereas no such variation was observed in the LS- group. No differences between T0 and T1 were found for ultrasonographic vascularization in either group, nor did the histological findings differ. There were no significant differences between the LS+ and LS- groups concerning intraoperative/postoperative blood loss (median 80.5 versus 94 ml respectively), duration of surgery (75 min in both groups) or postoperative morbidity. Lugol solution significantly reduces FT3 and FT4 levels in patients undergoing surgery for Graves' disease, but does not decrease intraoperative/postoperative blood loss, thyroid vascularization, duration of surgery or postoperative morbidity. NCT05784792 (https://www.clinicaltrials.gov).

Predicting Factors of Worse Prognosis in COVID-19: Results from a Cross-sectional Study on 52 Inpatients Admitted to the Internal Medicine Department.

The initial phases of the COVID-19 pandemic posed a real need for clinicians to identify patients at risk of poor prognosis as soon as possible after hospital admission. The study aimed to assess the role of baseline anamnestic information, clinical parameters, instrumental examination, and serum biomarkers in predicting adverse outcomes of COVID-19 in a hospital setting of Internal Medicine. Fifty-two inpatients consecutively admitted to the Unit of Internal Medicine "Baccelli," Azienda Ospedaliero - Universitaria Policlinico of Bari (February 1 - May 31, 2021) due to confirmed COVID-19 were grouped into two categories based on the specific outcome: good prognosis (n=44), patients discharged at home after the acute phase of the infection; poor prognosis, a composite outcome of deaths and intensive care requirements (n=8). Data were extracted from medical records of patients who provided written informed consent to participate. The two study groups had similar demographic, anthropometric, clinical, and radiological characteristics. Higher interleukin 6 (IL-6) levels and leucocyte count, and lower free triiodothyronine (fT3) levels were found in patients with poor than those with good prognosis. Higher IL-6 levels and leucocyte count, lower fT3 concentration, and pre-existing hypercholesterolemia were independent risk factors of poor outcomes in our study population. A predicting risk score, built by assigning one point if fT3 < 2 pg/mL, IL-6 >25 pg/mL, and leucocyte count >7,000 n/mm3, revealed that patients totalizing at least 2 points by applying the predicting score had a considerably higher risk of poor prognosis than those scoring <2 points (OR 24.35 (1.32; 448), p = 0.03). The weight of pre-existing hypercholesterolemia did not change the risk estimation. Four specific baseline variables, one anamnestic (pre-existing hypercholesterolemia) and three laboratory parameters (leucocyte count, IL-6, and fT3), were significantly associated with poor prognosis as independent risk factors. To prevent adverse outcomes, the updated 4-point score could be useful in identifying at-risk patients, highlighting the need for specific trials to estimate the safety and efficacy of targeted treatments.

Relationship between preoperative FT3 levels and new-onset atrial fibrillation after off-pump coronary artery bypass grafting.

Postoperative atrial fibrillation (POAF) is the most common arrhythmia after cardiac surgery. While thyroid dysfunction can predict POAF, the association between preoperative serum free triiodothyronine (FT3) levels and POAF in patients undergoing off-pump coronary artery bypass (OPCAB) grafting remains unclear. This study aimed to investigate the relationship between preoperative FT3 levels and POAF in OPCAB patients. This prospective observational study included patients with sinus rhythm and no history of atrial fibrillation or thyroid disease who underwent OPCAB and FT3 testing at the Tianjin Chest Hospital from June 2021 to March 2023. The relationship between FT3 level and POAF was evaluated using restricted cubic spline. Cox proportional hazards regression models were used to analyze the associations between FT3 concentration categories [low T3 syndrome (LT3S) (FT3 below the normal range), low normal FT3 (3.10-4.59 pmol/L), high normal FT3 (4.60-6.80 pmol/L)] and POAF, adjusting for potential confounders. Stratified analyses were performed to assess effect modification by gender and age (<60 vs. ≥60 years old). Among 875 patients, 259 (29.6%) developed POAF within 2 days after surgery. Restricted cubic spline analysis showed an S-shaped association between FT3 concentration and POAF risk. Compared to the low normal FT3 group, LT3S was associated with an increased risk of POAF [hazard ratio (HR), 1.41; 95% confidence interval (CI): 1.90-2.19], while high normal FT3 was associated with a decreased risk (HR, 0.72; 95% CI: 0.51-0.99). The association between FT3 and increased POAF risk was more pronounced in patients aged ≥60 years (HR, 1.41; 95% CI: 1.89-2.22). Preoperative FT3 levels most likely could predict POAF risk after OPCAB, especially in patients aged 60 years and older. Measuring FT3 preoperatively may identify high-risk patients benefiting from close monitoring and prophylactic treatment. Further investigation of thyroid hormone replacement therapy for LT3S is warranted.

Evaluation and diagnostic approach in patient with Perrault Syndrome

HIGHLIGHTS 1. The rare hereditary condition Perrault Syndrome is characterized by sensorineural hearing loss (SNHL) and ovarian dysfunction2. Cyclic estrogens and progesterone may be given to adolescents with amenorrhea to induce withdrawal bleeding and mimic the menstrual cycle. ABSTRACT Objectives: A multidisciplinary team, which included a reproductive endocrinologist and an otolaryngologist, identified Perrault Syndrome in a patient with secondary amenorrhea and bilateral sensorineural hearing loss. Case Report: A 16-year-old female presented to the obstetrics and gynecology clinic at a type B hospital with primary amenorrhea for one year. Menarche occurred at age 13, followed by regular menstrual cycles for two years, after which menstruation gradually ceased. She denied dysmenorrhea, constipation, leukorrhea, genital pruritus, growth retardation, and weight loss. The patient expressed concern about potential future infertility. At age 9, she was diagnosed with a viral infection by an ENT specialist due to bilateral hearing loss, leading to emotional disturbances. There was no history of prior medication, family illness, or chronic infections. Born at term via spontaneous vaginal delivery, the patient weighed 3,000 grams. Laboratory tests revealed normal T3 (1.51 ng/dl), FT4 (1.16 ng/dl), prolactin (18.25 ng/ml), estrogen (11 pg/ml), and progesterone (0.1 pg/ml) levels, but elevated FSH (66.46 mIU/ml) and LH (29.97 mIU/ml) levels. Symptomatic treatment included bone conduction hearing aids and estrogen replacement therapy. Conclusion: Perrault Syndrome, a rare hereditary condition, manifests as sensorineural hearing loss (SNHL) and ovarian dysfunction, including primary ovarian insufficiency (POI) and gonadal dysgenesis, in individuals with a 46, XX karyotype. Molecular diagnosis remains challenging. Consultation with a pediatric endocrinologist can guide cyclic estrogen and progesterone therapy to induce withdrawal bleeding in adolescents with amenorrhea. Women at risk of ovarian failure should consider donor eggs or oocyte cryopreservation. Avoiding aminoglycosides and excessive noise is crucial for managing hearing loss.

Assessing the causal relationship between obesity and hypothyroidism using Mendelian randomization.

To explore the causal relationship between obesity and hypothyroidism and identify risk factors and the predictive value of subclinical hypothyroidism (SCH) in obese patients using Mendelian randomization, this study employed five Mendelian randomization methods (MR Egger, Weighted Median, Inverse Variance Weighted, Simple Mode, and Weighted Mode) to analyze clinical data from 308 obese patients at the People's Hospital of Xinjiang Uygur Autonomous Region, from January 2015 to June 2023. Patients were divided based on thyroid function tests into normal (n = 173) and SCH groups (n = 56). Comparative analyses, along with univariate and multivariate logistic regression, were conducted to identify risk factors for SCH in obese patients. A significant association between obesity and hypothyroidism was established, especially highlighted by the inverse variance weighted method. SCH patients showed higher ages, thyroid-stimulating hormone levels, and thyroid autoantibody positivity rates, with lower T4 and FT4 levels. Age, FT4, thyroid autoantibodies, TPO-Ab, and Tg-Ab were confirmed as risk factors. The predictive value of FT4 levels for SCH in obesity was significant, with an Area Under the Curve (AUC) of 0.632. The study supports a potential causal link between obesity and hypothyroidism, identifying specific risk factors for SCH in obese patients. FT4 level stands out as an independent predictive factor, suggesting its utility in early diagnosis and preventive strategies for SCH.

Correlation analysis between serum free triiodothyronine and C-peptide-based insulin resistance index in euthyroid adults

Objective: To explore the correlation between serum free triiodothyronine (FT3) and C-peptide-based insulin resistance index (HOMA2 IR-CP) in euthyroid adults. Methods: A cross-sectional study. The clinical data of euthyroid adult participants who underwent physical examination in the Second Medical Center of Chinese PLA General Hospital from January to December in 2019 were retrospectively analyzed. According to the HOMA2 IR-CP level, the participants were divided into HOMA2 IR-CP>2.18 group (n=3 463) and HOMA2 IR-CP≤2.18 group (n=8 204). Univariate Pearson correlation analysis and multivariate logistic regression analysis were used to analyze the correlation between FT3 and HOMA2 IR-CP. The interaction model was used to analyze the interaction between FT3 and related factors, and the dose-response relationship between continuity variable FT3 and HOMA2 IR-CP was explored by using restricted cubic spline plots. Results: A total of 11 667 euthyroid adult participants aged (50.7±10.0)years were recruited according to the inclusion and exclusion criteria, with 7 756 males and 3 911 females. The proportion of males, body mass index, systolic blood pressure, glycated hemoglobin A1c, fasting plasma glucose, triglyceride, hemoglobin, alanine aminotransferase and FT3 levels in HOMA2 IR-CP>2.18 group were significantly higher than those in HOMA2 IR-CP≤2.18 group (all P<0.05). The levels of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and free thyroxine in HOMA2 IR-CP>2.18 group were lower than those in HOMA2 IR-CP≤2.18 group (all P<0.001). Univariate Pearson correlation analysis showed that FT3 was associated with HOMA2 IR-CP (r=0.21, P<0.001). Multivariate logistic regression analysis suggested an association between FT3 and HOMA2 IR-CP after adjusting for confounding factors(Pfor trend<0.001). Subgroup analysis showed an association between FT3 and HOMA2 IR-CP in different subgroups of gender, age and glucose metabolism status (Pfor trend<0.05). Multiplication interaction analysis suggested that there was an interaction between FT3 and age (Pinteraction<0.001). Restricted cubic spline model analysis demonstrated that the correlation between FT3 and HOMA2 IR-CP was linear (Poverall<0.001, Pnonlinear=0.479). Conclusions: There is a correlation between serum FT3 and HOMA2 IR-CP in euthyroid adults. With the increase of FT3 level, insulin resistance increases gradually.

Longitudinal Evaluation of Reproductive Endocrine Function in Men with ACTH-Dependent Cushing Syndrome.

Hypogonadism may be caused by Cushing syndrome (CS) and may intensify its adverse consequences. To determine the frequency of male hypogonadism before and after curative surgery for CS, and its cause. Post-hoc analyses of prospective cohort studies. Clinical research center. Men with ACTH-dependent CS. Cohort 1 (C1) (n=8, age 32.5±12 y; studied 1985-1989); Cohort 2 (C2) (n=44, 42.7 ± 15.1 y; studied 1989-2021). C1: Every 20-minute blood sampling for 24h before and 1-40 months after surgical cure. Three subjects underwent GnRH stimulation tests pre- and post-surgery. C2: Hormone measurements at baseline and 6 and 12 months (M) post-cure. C1: LH, FSH, LH pulse frequency and LH response to GnRH. C2: LH, FSH, testosterone (T), free T, fT4, T3, TSH and UFC levels and frequency of hypogonadism pre- and post-surgery. C1: mean LH and LH pulse frequency increased after surgery (p < 0.05) without changes in LH pulse amplitude, mean FSH, or peak gonadotropin response to GnRH. C2: 82% had baseline hypogonadism (total T 205 ± 28 ng/dL). Thyroid hormone levels varied inversely with UFC and cortisol. LH, total and free T, and SHBG increased at 6M and 12M post surgery, but hypogonadism persisted in 51% at 6M and in 26% at 12M. Hypogonadism in men with CS is widely prevalent but reversible in ∼75% of patients one year after surgical cure and appears to be mediated through suppression of hypothalamic GnRH secretion, and modulated by thyroid hormones.

Thyroid dysfunction in the wake of Omicron: understanding its role in COVID-19 severity and mortality.

SARS-CoV-2 can invade the thyroid gland. This study was to delineate the risk of thyroid dysfunction amidst the prevalence of the Omicron variant, and to investigate the correlation between thyroid function and Coronavirus disease 2019 (COVID-19) outcomes. The study also aimed to ascertain whether thyroid dysfunction persisted during COVID-19 recovery phase. This was a retrospective cohort study. COVID-19 patients from the Renmin Hospital of Wuhan University, China during the epidemic of Omicron variants were included, and their thyroid function were analyzed in groups. A history of thyroid disease was not associated with COVID-19 outcomes. COVID-19 can lead to a bimodal distribution of thyroid dysfunction. The severity of COVID-19 was inversely proportional to the levels of thyroid- stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4), leading to a higher prevalence of thyroid dysfunction. Severe COVID-19 was a risk factor for euthyroid sick syndrome (ESS) (OR=22.5, 95% CI, 12.1 - 45.6). Neutrophil to lymphocyte ratio mediated the association between severe COVID-19 and ESS (mediation effect ratio = 41.3%, p < 0.001). ESS and decreased indicators of thyroid function were associated with COVID-19 mortality, while high levels of FT3 and FT4 exhibited a protective effect against death. This effect was more significant in women (p < 0.05). During the recovery period, hyperthyroidism was quite uncommon, while a small percentage of individuals (7.7%) continued to exhibit hypothyroidism. COVID-19 severity was linked to thyroid dysfunction. Severe COVID-19 increased the risk of ESS, which was associated with COVID-19 mortality. Post-recovery, hyperthyroidism was rare, but some individuals continued to have hypothyroidism.

Effects of low-dose methotrexate with MMI in patients with Graves' disease: results of a randomized clinical trial.

Supplemental methotrexate (MTX) may affect the clinical course of Graves' disease (GD). Evaluate efficacy of add-on MTX on medical treatment in GD. Prospective, open-label, randomized supplementation controlled trial. Academic endocrine outpatient clinic. One hundred and fifty-three untreated hyperthyroid patients with GD. Patients received MTX 10 mg/d with methimazole (MMI) or MMI only. MTX and MMI were discontinued at months 12-18 in euthyroid patients. Discontinuation rate at months 18 in each group. In the MTX with MMI group, the discontinuation rate was higher than the MMI group at months 15-18 (50.0 vs. 33.3%, P=0.043, 95% CI 1.020 to 3.922; and 55.6 vs 38.9%, P=0.045, 95%CI 1.011 to 3.815, respectively). The decrease in TRAb levels in the MTX with MMI group was significant from baseline to months 6 compared to the MMI alone group [MTX+MMI 67.22% (43.12-80.32), MMI 54.85% (33.18-73.76), P= 0.039) and became more significant from months 9 [MTX+MMI 77.79% (62.27-88.18), MMI 69.55% (50.50-83.22), P= 0.035] to months 18 (P < 0.01 in 15-18 months). A statistically significant difference between the levels of TRAb in the MTX with MMI group and the MMI group at 9-18 months. There were no significant differences in the levels of FT3, FT4 and TSH between two groups. No serious drug-related adverse events were observed in both groups(P=0.771). Supplemental MTX with MMI resulted in higher discontinuation rate and improvement in decreased TRAb levels to homeostatic levels faster than methimazole treatment alone at months 12-18.

The Effects of Vibegron Add-on Therapy on Alpha 1-Blocker Therapy for Sexual Function and Overactive Bladder Symptoms in Benign Prostatic Hyperplasia: A Prospective, Open-Label Study.

Background: The effect of combining an α1-adrenergic receptor blocker (α1-blocker) and the β3-adrenoceptor agonist vibegron for treating persistent overactive bladder (OAB) symptoms associated with benign prostatic hyperplasia (BPH) on sexual function remains uncertain. Therefore, we aimed to evaluate the effects of vibegron as an add-on to α1-blocker therapy on both OAB and sexual function. Methods: Forty-three patients with BPH in whom OAB symptoms were inadequately controlled by α1-blocker treatment were included in this prospective open-label study. The OAB Symptom Score (OABSS), International Prostate Symptom Score (IPSS), 15-item International Index of Erectile Function (IIEF-15), and Erection Hardness Score (EHS), as well as the residual urine volume and serum-free testosterone (FT) and C-reactive protein (CRP) levels, were evaluated before and 8 weeks after the daily administration of 50 mg vibegron/α1-blocker combination therapy. Results: Vibegron/α1-blocker combination therapy significantly improved the OABSS (from 6.9 ± 2.6 to 5.1 ± 2.9, p < 0.0001) and IIEF intercourse satisfaction domain (from 1.1 ± 2.3 to 1.9 ± 2.6, p = 0.02). No significant differences were observed for the IPSS, EHS, total IIEF-15 score, residual urine volume, and serum FT and CRP levels. Conclusions: The study findings suggest that vibegron/α1-blocker combination therapy improves OAB and sexual satisfaction.

Frequency of Non-Thyroidal Illness Syndrome in Pediatric Patients with Sepsis and Septic Shock

Abstract Background Non-Thyroidal Illness Syndrome (NTIS) is considered when patients demonstrate abnormal thyroid functions and levels decrease at onset of infection and keep decreasing with disease progression. Levels usually get normalized after the illness is cured. NTIS is not studied well in pediatric population. Aim of the Work Assess the hormonal changes of NTIS in sepsis and septic shock patients. Furthermore, Follow up the severity of NTIS and its effect on outcome. Patients and Methods This study (1st phase: Cross-sectional, 2nd phase: Prospective) included 40 critically ill children categorized into two groups: (i) Sepsis group : was defined according to standard international criteria using pediatric Sequential Organ Failure Assessment (p SOFA) score and sepsis was considered when p SOFA score &amp;gt; 2 (ii) Septic shock group: was defined by a vasopressor requirement to maintain a mean arterial pressure ≥ 65 mm Hg and having a serum lactate level &amp;gt; 2 mmol/L despite adequate fluid resuscitation (Singer et al., 2016), with 20 patients in each group. Patients were admitted to the pediatric intensive care unit (PICU). Thyroid hormone levels were assessed and compared in day 1 and day 5 in all patients and subgroups. All patients were followed up until discharge or death. ROC curve and Univariate and multivariate approaches were used to assess the link between thyroid hormones and prediction of mortality. Results NTIS was found in 47.5% of patients. NTIS was higher among septic shock group than sepsis 65.5% versus 30% (p value = 0.027). NTIS was associated with each of ventilation, catecholamines infusion and SOFA score (p value =0.044, 0,027 and 0.033) respectively. FT3 (Free triiodothyronine) levels were lower and rT3 (reverse T3) levels were higher in day 5 of illness than day 1 (p value =0.041and 0.000) respectively. Furthermore, FT3 levels in day 5 were lower, and rT3 levels in day 1 and day 5 were higher in non survivors than survivors (p value =.0.002, 0.015 and 0.003) respectively. ROC curve to assess thyroid hormone levels, SOFA score and CRP (C-reactive protein) as predictors of mortality revealed that FT3 levels in day 5 was the best in predicting PICU mortality (sensitivity 100%, and specificity 68.42%), Followed by SOFA score day 5 (sensitivity 100%, and specificity 57.89%). In the multivariate regression analysis, we discovered that high rT3 levels in day1 and CRP in day 5 were independently associated with PICU mortality. Conclusion NTIS is common among critically ill children and higher among septic shock group than sepsis. Also, Beside the SOFA score, FT3 measured in day5 of illness and rT3 measured in day1 of illness were the best predictors of PICU mortality.

Association Between Subclinical Thyroid Dysfunction and Cognitive Decline: Findings From the ELSA-Brasil Study.

Thyroid dysfunction has been associated with cognitive decline and dementia. However, the role of subtle thyroid hormone alterations in cognitive function is still debatable. Participants without overt thyroid dysfunction aged 35-74 years at baseline were evaluated in 3 study waves (2008-2010, 2012-2014, and 2017-2019). We assessed baseline thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3). Cognitive performance was evaluated every 4 years in each wave using 10-word immediate and late recall, word recognition, semantic (animals category) and phonemic (letter f) verbal fluency, and the trail-making B-version tests. A global composite z-score was derived from these tests. The associations of TSH, FT4, and FT3 levels with cognitive decline over time were evaluated using linear mixed-effect models adjusted for sociodemographic, clinical, and lifestyle variables. In 9524 participants (mean age 51.2 ± 8.9 years old, 51% women, 52% White), there was no association between baseline TSH, FT4, and FT3 levels and cognitive decline during the follow-up. However, increase in FT4 levels over time was associated with faster memory (β = -0.004, 95% CI = -0.007; -0.001, p = .014), verbal fluency (β = -0.003, 95% CI = -0.007; -0.0005, p = .021), executive function (β = -0.004, 95% CI = -0.011; -0.003, p < .001), and global cognition decline (β = -0.003, 95% CI = -0.006; -0.001, p = .001). Decrease in FT4 levels over time was associated with faster verbal fluency (β = -0.003, 95% CI = -0.007; -0.0004, p = .025) and executive function (β = -0.004, 95% CI = -0.007; -0.0003, p = .031) decline. An increase or decrease in FT4 levels over time was associated with faster cognitive decline in middle-aged and older adults without overt thyroid dysfunction during 8 years of follow-up.

The association between TSH and thyroid hormones in the normal or subclinical dysfunction range with left ventricular diastolic dysfunction

Thyroid hormones modulate the cardiovascular system. However, the effects of subclinical thyroid dysfunction and euthyroidism on cardiac function remain unclear. We investigated the association between left ventricular (LV) diastolic dysfunction and subclinical thyroid dysfunction or thyroid hormones within the reference range. This cross-sectional study included 26,289 participants (22,197 euthyroid, 3,671 with subclinical hypothyroidism, and 421 with subclinical thyrotoxicosis) who underwent regular health check-ups in the Republic of Korea. Individuals with thyroid stimulating hormone (TSH) levels > 4.2 µIU/mL and normal free thyroxine (FT4, 0.78–1.85 ng/dL) and triiodothyronine (T3, 76–190 ng/dL) levels were defined as having subclinical hypothyroidism. Individuals with serum TSH levels < 0.4 µIU/mL and normal FT4 and T3 levels were defined as having subclinical thyrotoxicosis. The cardiac structure and function were evaluated using echocardiography. LV diastolic dysfunction with normal ejection fraction (EF) was defined as follows: EF of > 50% and (a) E/e’ ratio > 15, or (b) E/e’ ratio of 8–15 and left atrial volume index ≥ 34 mL/m2. Subclinical hypothyroidism was significantly associated with cardiac indices regarding LV diastolic dysfunction. The odds of having LV diastolic dysfunction was also increased in participants with subclinical hypothyroidism (adjusted odds ratio [AOR] 1.36, 95% confidence interval [CI], 1.01–1.89) compared to euthyroid participants. Subclinical thyrotoxicosis was not associated with LV diastolic dysfunction. Among the thyroid hormones, only serum T3 was significantly and inversely associated with LV diastolic dysfunction even within the normal range. Subclinical hypothyroidism was significantly associated with LV diastolic dysfunction, whereas subclinical thyrotoxicosis was not. Serum T3 is a relatively important contributor to LV diastolic dysfunction compared to TSH or FT4.

Radioactive Iodine Treatment of Graves' Disease: Predictors of Time Interval Greater than 90 Days for Treatment Success.

Radioactive iodine (RAI) is often used for treating Graves' disease. We study predictors for a time interval greater than 90 days between RAI treatment and success. This was a retrospective study of 106 patients with Graves' disease seen at a public hospital in suburban New York City. Predictor variables were from demographics, prior treatment history, iodine 131 RAI treatment, and thyroid function prior to RAI treatment. There were 62.3% that had a time interval greater than 90 days between RAI treatment and success. Only the thyroid function prior to RAI treatment variable of free thyroxine (FT4) had statistically significantly increased odds for time interval greater than 90 days between RAI treatment and success (OR:1.28, 95% CI:1.02, 1.61, p = 0.03). Demographics, prior treatment history, and iodine 131 RAI treatment variables were not significantly associated with time interval greater than 90 days between RAI treatment and success. Thyroid function measured by FT4 was significantly associated with time interval greater than 90 days between RAI treatment and success. We suggest that the thyroid function variable of FT4 levels at initial diagnosis is most helpful for understanding the prognosis and success rate for using RAI treatment in patients with Graves' disease.

Expressions of glycemic parameters, lipid profile, and thyroid hormone in patients with type 2 diabetes mellitus and their correlation.

This study aimed to investigate the expressions of glycemic parameters, lipid profile, and thyroid hormone in type 2 diabetes mellitus (T2DM) patients and their correlation. Eighty-fourpatients with T2DM in our hospital were included as the observation group. The T2DM patients were divided into mild group, moderate group, and severe group according to the fasting plasma glucose (FPG) level. Another 84 healthy subjects in the same period of health examination in our hospital were included as the control group. The levels of glycemic parameters, (HbA1c and FPG), lipid profile (TC, TG, LDL-C, and HDL-C) and thyroid hormone (FT3, TSH, and FT4) were measured by automatic biochemical analyzer. The correlation between glycemic parameters, lipid profile, and thyroid hormone was analyzed by Pearson correlation analysis. The FPG, TC, TG, LDL-C, HbA1c, and TSH levels were significantly elevated, while the HDL-C and FT3 levels were significantly declined in the observation group versus to control group (p < .05). The levels of HbA1c, FPG, TC, LDL-C, and TSH were significantly increased, while the levels of HDL-C and FT3 were decreased in moderate and severe groups, when compared to mild group (p < .05). The levels of HbA1c, FPG, TC, LDL-C and TSH were higher, while the level of FT3 was lower in severe group than those in moderate group (p < .05). Pearson Correlation analysis showed that FT3 level in T2DM patients was positively correlated with FPG, HbAlc, TC, TG, and LDL-C levels (p < .05), but negatively correlated with HDL-C level (p < .05). TSH level was negatively correlated with FPG, HbAlc, TC, TG, and LDL-C levels (p < .05), while positively correlated with HDL-C level. The thyroid hormone levels were of clinical significance in evaluating glycolipid metabolism and severity of T2DM. Clinical detection of glycolipid metabolism and thyroid hormone levels in T2DM patients is of great significance for diagnosis, evaluation, and targeted treatment of the disease.

Titanium dioxide nanoparticles Disrupt ultrastructure and function of Rat thyroid tissue via oxidative stress

Nano-TiO2 is widely used in various fields such as industry, daily necessities, food and medicine. Previous studies have shown that it can enter mammalian tissues through the digestive tract or respiratory tract and have effects on various organs and systems. However, the effect of nano-TiO2 on the mammalian thyroid gland has not been reported. In this study, we fed SD rats with rutile nano-TiO2 at a dose of 5 mg/kg body weight for 3 weeks, and then examined the thyroid histology and thyroid function of the rats. In vitro experiments were conducted to determine the effects of nano-TiO2 on the viability, apoptosis, inflammatory factors, antioxidant enzymes, and oxidative stress of human thyroid follicular epithelial cells. Histological evidence showed abnormal morphology of rat thyroid follicles and organelle damage in follicular epithelial cells. Nano-TiO2 caused a decrease in the level of sodium/iodide symporter (NIS), an increase in the level of apoptotic protein cleaved-caspase 3, and an increase in the levels of pro-inflammatory factors IL-1β and TNF-α in rat thyroid tissue. Nano-TiO2 also resulted in increased serum FT4 and TPO-Ab levels. In in vitro experiments, nano-TiO2 reduced the viability of human thyroid follicular cells, downregulated the levels and activities of antioxidant enzymes CAT, GPX1 and SOD, and increased the levels of ROS and MDA caused by oxidative stress. These results indicate that nano-TiO2 damages the structure and function of thyroid follicular epithelial cells through oxidative stress. Long-term exposure to nano-TiO2 could be a potential risk factor for thyroid dysfunction.

Stability analysis of a mathematical model for methimazole dosing in graves' hyperthyroidism: A dynamic approach

This study explores a novel mathematical model for analyzing methimazole (MMI) therapy in patients with Graves' disease, a common autoimmune cause of hyperthyroidism. The model leverages a system of ordinary differential equations to capture the interplay between key factors: methimazole concentration, thyroid-stimulating hormone (TSH), free thyroxine (FT4) concentration, thyroid-stimulating hormone receptor antibody (TRAb) concentration, and functional thyroid gland size (V). Thirteen parameters account for the underlying physiological processes. Stability analysis were employedby Lyapunov stability theory and LaSalle's principle, to demonstrate the model's asymptotic stability. This implies the system converges towards a steady state under defined conditions. Additionally, a clinically relevant chart is constructed based on FT4 levels and treatment duration.For model validation, patient data is utilized within SimBiology simulations implemented in MATLAB. These simulations offer valuable insights into the dynamic response of hyperthyroidism to MMI treatment. This approach holds promise for future applications in optimizing treatment strategies and facilitating personalized medicine approaches.

Relationship between thyroid hormone levels and metabolic dysfunction associated steatotic liver disease in patients with type 2 diabetes: A clinical study.

This study investigates the correlation between thyroid hormone levels and metabolic dysfunction in patients with type 2 diabetes mellitus (T2DM) who exhibit normal thyroid function and metabolic dysfunction associated with steatotic liver disease (MASLD). The objective is to identify a scientific basis for the management of T2DM complicated by MASLD, aiming to refine clinical strategies and enhance patient well-being. Statistical analysis was conducted using SPSS 26.0, employing independent sample t-tests for normally distributed data and logarithmic transformations for non-normal data to meet analysis prerequisites. Multifactorial logistic regression analysis elucidated the impact of various factors on the risk of MASLD in T2DM patients. Elevated levels of FT3 may be associated with an increased risk of nonalcoholic fatty liver disease. Additionally, the FT3/FT4 ratio has been validated as an effective serological marker for predicting the risk of MASLD. In patients with DM2 and normal thyroid function, changes in thyroid hormone levels are closely related to the occurrence of MASLD. Elevated levels of FT3, total triiodothyronine (TT3), and thyroid-stimulating hormone are associated with an increased risk of MASLD. FT3, TT3, and thyroid-stimulating hormone have important clinical value in the diagnosis of patients with T2DM complicated with MASLD.

Association between maternal age and sex-based neonatal free triiodothyronine levels

BackgroundAdvanced maternal age may affect the intrauterine environment and increase the risk of neurodevelopmental disorders in offspring. Thyroid hormones are critical for fetal neurological development but whether maternal age influences fetal thyroid hormone levels in euthyroid mothers is unknown.ObjectiveThis study evaluated the association between cord blood thyroid hormones and maternal age, fetal sex, maternal thyroid function, and other perinatal factors.MethodsThe study population consisted of 203 healthy women with term singleton pregnancies who underwent elective cesarean section. Maternal levels of free T3 (fT3), free T4 (fT4) and TSH before delivery, and cord levels of fT3, fT4 and TSH were measured. Spearman’s correlation coefficient and multiple linear regression analyses were performed to determine the correlation between cord thyroid hormone parameters and maternal characteristics.ResultsThere were no significant differences in maternal serum or cord blood thyroid hormone levels between male and female births. In multivariate linear regression analysis, maternal age and maternal TSH values were negatively associated with the cord blood levels of fT3 in all births, after adjusting for confounding factors. Maternal age was more closely associated with the cord blood levels of fT3 in female than in male births.ConclusionThe inverse association between maternal age and cord blood levels of fT3 in euthyroid pregnant women suggested an impact of maternal aging on offspring thyroid function.