Serum FT4 Research Articles

Environmental exposure to perchlorate, nitrate and thiocyanate, and thyroid function in Chinese adults: A community-based cross-sectional study

BackgroundEvidence on environmental exposure to perchlorate, nitrate, and thiocyanate, three thyroidal sodium iodine symporter (NIS) inhibitors, and thyroid function in the Chinese population remains limited. ObjectiveTo investigate the associations of environmental exposure to perchlorate, nitrate, and thiocyanate with markers of thyroid function in Chinese adults. MethodsA total of 2441 non-pregnant adults (mean age 50.4 years and 39.1% male) with a median urinary iodine of 180.1 μg/L from four communities in Shenzhen were included in this cross-sectional study. Urinary perchlorate, nitrate, thiocyanate, and thyroid profiles, including serum free thyroxine (FT4), total thyroxine (TT4), free triiodothyronine (FT3), total triiodothyronine (TT3), and thyroid stimulating hormone (TSH), were measured. Generalized linear model was applied to investigate the single-analyte associations. Weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) models were used to examine the association between the co-occurrence of three anions and thyroid profile. ResultsThe median levels of urinary perchlorate, nitrate, and thiocyanate were 5.8 μg/g, 76.4 mg/g, and 274.1 μg/g, respectively. After adjusting for confounders, higher urinary perchlorate was associated with lower serum FT4, TT4, and TT3, and higher serum FT3 and TSH (all P < 0.05). Comparing extreme tertiles, subjects in the highest nitrate tertile had marginally elevated TT3 (β: 0.02, 95% CI: 0.00–0.04). Each 1-unit increase in log-transformed urinary thiocyanate was associated with a 0.04 (95% CI: 0.02–0.06) pmol/L decrease in serum FT3. The WQS indices were inversely associated with serum FT4, TT4, and FT3 (all P < 0.05). In the BKMR model, the mixture of three anions was inversely associated with serum FT4, TT4, and FT3. ConclusionsOur study provides evidence that individual and combined environmental exposure to perchlorate, nitrate, and thiocyanate are associated with significant changes in thyroid function markers in the Chinese population with adequate iodine intake.

Serum lipid profile in relation to free thyroxine and the effect of levothyroxine treatment on lipids in patients with isolated hypothyroxinemia during pregnancy: a single-center retrospective study

BackgroundThyroid function is widely considered a lipid metabolism regulator. However, studies on lipid metabolism in pregnant women with low free thyroxine (FT4) levels are limited and inconclusive. Furthermore, the association between maternal FT4 deficiency and adverse lipid metabolic parameters is unknown. Therefore, we aimed to investigate this association and the effects of levothyroxine (L-T4) treatment on these metabolic indicators.MethodsThis retrospective study included 164 patients with isolated hypothyroidism (IH) (FT4 levels below the 5th percentile with normal thyroid stimulating hormone levels according to the gestational-specific reference range) and 407 euthyroidism patients (control group who had regular antenatal examinations at Zhejiang Provincial People's Hospital, Hangzhou, China) between January 1, 2019, and December 31, 2020. Patients with IH were divided into levothyroxine (L-treatment group, n = 77) and dietary iodine supplement treatment groups (dietary treatment group, n=87) according to the hospital’s treatment policy and clinical experience. The intervention lasted for at least 8 weeks. Metabolic indicators, including thyroid function and lipid parameters, were collected at least twice before and after the intervention. Other data collected included maternal age, history of abortion, prepregnancy BMI, and gestational weight gain (Fig. 1).ResultsCompared with the control group, Patients with IH had a higher degree of dyslipidemia, reflected in elevated total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and apolipoprotein B (Apo B) levels. In IH patients, an inverse correlation was found between FT4 and TG levels, which remained after adjusting for prepregnancy BMI. The L-treatment group demonstrated a significantly slower rate of hypercholesterolemia progression during pregnancy than the dietary treatment group. In addition, there was a relationship between the therapeutic effect and the degree of disease, with the main factors being FT4, TSH and TG levels prior to starting treatment.ConclusionsLow FT4 levels were associated with elevated blood lipid levels. Serum FT4 and lipid levels in patients could be improved by medical intervention.

Study of Relationship Between Iron Deficiency and Thyroid Function in Pregnant Females.

Iron is essential for the normal functioning of thyroid peroxidase and iron deficiency is very commonly encountered during pregnancy. Thyroid disorders and iron deficiency are associated with obstetrical and fetal complications. The aim of the study was to find out the relationship between iron deficiency and thyroid function in pregnant females during first trimester. The present cross-sectional observational study was conducted among first trimester pregnant females at the Department of Medicine, Obstetrics and Gynecology, and Biochemistry at Atal Bihari Vajpayee Institute of Medical Sciences and Dr. Ram Manohar Lohia Hospital, New Delhi. Hundredpregnant women were included in this study. On the basis of serum ferritin value, the study population was divided into two groups namely iron deficient and non-iron deficient. Serum thyroid-stimulating hormone (TSH), FT4, and anti-thyroid peroxidase (TPO) values were then compared between the two groups. In the present study, 68% of the females were iron deficient. In the Iron deficient group, serum TSH and anti-TPO levels were significantly higher as compared to that in the non-iron deficient group (35.29% vs. 6.25% and 22.06% vs. 3.13%; p=0.001 and 0.018, respectively). A positive correlation was obtained between FT4 and ferritin with correlationcoefficient of 0.907 and p-value of 0.0001. Serum TSH levels and serum anti-TPO levels were inversely correlated with ferritin. Univariate logistic regression analysis revealed that iron deficiency was associated with an increased risk ofsubclinical hypothyroidismwith odds ratio (OR)8.182(95% CI: 1.798-37.234, p=0.007) and raised anti-TPO with OR 8.77 (95% CI: 1.105-69.681; p=0.040). Iron deficiency is frequent during the first trimester of pregnancy and is associated with an increased risk of subclinical hypothyroidism and thyroid autoimmunity.

The associations between thyroid-related hormones and the risk of thyroid cancer: An overall and dose-response meta-analysis.

Thyroid cancer (TC) is one of the most common malignant tumours of the endocrine system. Thyroid-stimulating hormone (TSH) is known as being a risk factor for TC, but other thyroid-related hormones are inconsistently associated with TC. The purpose of this study was to comprehensively evaluate the relationships between thyroid-related hormones and the risk of TC. This study utilized searches of PubMed, Embase, Web of Science and Cochrane library up to the date of March 31st, 2022. Additionally, we performed a systematic review of related original studies combining overall and dose-response meta-analyses. A total of 30, 5 and 7 articles were included in the meta-analyses of TSH, Free triiodothyronine (FT3), free thyroxine (FT4) and TC risk with 58437, 6813 and 7118 participants respectively. An increased risk of TC was associated with high TSH exposure (OR=1.28, 95% CI: 1.19-1.37, P < 0.001) in the overall meta-analysis. For every 1 mU/L increase in TSH, the risk of TC increased by 16%. However, in those studies that used healthy subjects as controls, the association was not statistically significant(P=0.62). Additionally, high serum FT3 demonstrated a reduced risk of TC, with a combined OR of 0.86 in the fixed-effect model (95% CI: 0.81-0.90, P < 0.001). In addition, a statistically significant increase in TC risk was found when FT4 concentrations reached a certain threshold (approximately 2.2 ng/dL) in the dose-response meta-analysis. Significant associations between thyroid-related hormones and the risk of TC were found in this study. Further research is needed to understand the underlying mechanisms.

Association of maternal TSH and neonatal metabolism: A large prospective cohort study in China.

Neonatal metabolites are very important in neonatal disease screening, and maternal thyroid hormones play an important role in fetal and neonatal health. Our study aimed to explore the association of maternal thyroid hormones with neonatal metabolites and identify an important time windows. Pregnant women were recruited in Jinan Maternity and Child Care Hospital and followed up until delivery. Multivariate generalized linear regression models (GLMs) and restricted cubic spline (RCS) regression analysis models were used to investigate the associations of maternal TSH and FT4 with neonatal metabolites. In total, 6,653 pairs of mothers and newborns were enrolled in our study. We identified 5 neonatal metabolites, including arginine/ornithine (Arg/Orn), C14:1/C2, C18:1, C3DC+C4OH and C8:1, that were significantly associated with maternal serum TSH during the whole pregnancy (P < 0.05), especially in the first trimester. Moreover, 10 neonatal metabolites were significantly associated with maternal serum FT4 (P < 0.05), most of which had positive correlations with maternal FT4 in the first trimester (P < 0.05). Some neonatal metabolites also had linear or nonlinear dose-effect relationships with maternal serum TSH and FT4 during the whole pregnancy, particularly in the first trimester. Our study, for the first time, provides epidemiological evidence that maternal serum TSH and FT4, especially during the first trimester, are associated with linear or nonlinear variations in neonatal metabolites. Efforts to identify newborn metabolism levels should carefully consider the effects of maternal thyroid function.

Pregnancy disrupts the accuracy of automated fT4 immunoassays.

Thyroid hormone measurements are often performed in pregnant women, as hypo- and hyperthyroidism during pregnancy can severely affect the fetus. Serum free thyroxine (fT4) measurements are well known for their analytical challenges, due to low serum concentrations and the subtle equilibrium between free and bound T4 (to thyroid-binding globulin (TBG), transthyretin and albumin). Pregnant women have high TBG concentrations due to an increase in human chorionic gonadotropin (hCG) and estrogen and lower albumin concentrations which change the equilibrium and may affect the validity of fT4 measurements in their samples. As accurate serum fT4 measurements in pregnant women are important for the long-term health of the fetus, we aimed to evaluate the accuracy of several fT4 immunoassays in the serum of pregnant women. FT4 was measured in healthy controls and pregnant women using a candidate-reference method (LC-MS/MS) and five commercially available automated immunoassays (Alinity (Abbott), Atellica (Siemens), Cobas (Roche), Lumipulse (Fujirebio) and UniCel DXI (Beckman Coulter)). Method comparisons (Bland Altman plots and Passing and Bablok analyses) were performed. Serum samples from both healthy controls (n = 30) and pregnant women (n = 30; mean gestational age, 24.8 weeks) were collected. The fT4 immunoassays deviated +7 to +29% more from the LC-MS/MS in serum samples of pregnant women than healthy controls (falsely high). Our results indicate that immunoassays overestimate fT4 in pregnant women, which might lead to an overestimation of thyroid status. Physicians and laboratory specialists should be aware of this phenomenon to avoid drawing false conclusions about thyroid function in pregnant women.

Decreased circulating levels of free triiodothyronine in Sepsis children and correlation analysis

BackgroundIntensive physical stress in sepsis can induce the disorder of endocrine function and impact the clinical course and prognosis. Low T3 syndrome has been verified to be the predictive indicator of poor prognosis in several researches. Reports on the influence factors of thyroid hormonal levels in children with severe sepsis are rare. We aim to investigate the thyroid hormonal variations in the course of sepsis and analyze that how to be affected by clinical data and inflammatory biomarkers.MethodsIn the case-control study, 184 children with sepsis and 323 controls were included in Tongji Hospital, Wuhan, China, in 2019. Data on clinical and inflammatory parameters were collected from all participants. Circulating FT3(Free Triiodothyronine) levels were measured by Electrochemiluminescence immunoassay. Finally, we investigated the correlation between FT3 and related variables with linear regression analysis.ResultsSerum FT3 was lower in the sepsis group than in control group(2.59 + 1.17 vs 2.83 + 1.01 pg/mL, p < 0.05). Significant moderately negative correlations(|r| > 0.3) of FT3 levels with ferritin, PCT, duration of symptoms, SOFA score, and mortality were revealed. Moreover, we observed that FT3 had the positive correlation with albumin, as well as white blood cell count.ConclusionsConcentrations of serum FT3 are dramatically declined in sepsis children than in control children. Our results demonstrate that recognizing the potential abnormality of thyroid hormones in sepsis patients and examine timely through abnormal common clinical data and inflammatory biomarkers is a fine option.

Type 2 Deiodinase A/G (Thr92Ala) Polymorphism and Circulating Thyroid Hormone Level of Childbearing Age Women in Area Replete with Iodine Deficiency Disorders

BACKGROUND: Iodothyronine deiodinase (DIO) is an enzyme that regulates thyroid hormone activity. DIO consists of three types: deiodinase 1 (D1), 2 (D2), and 3 (D3). D2 is a gene that plays an important role in regulation of the biochemistry of the thyroid hormone in several tissues. D2 also plays a role in the production of triiodothyronine and controlling thyroid hormone signals. This study measured the observation that about 15% of the normal population show that D2 gene polymorphism (Thr92Ala) potentially affects the activity of D2. AIM: This study aimed to determine D2 polymorphisms and their association with thyroid hormone levels in women of childbearing age in replete iodine deficiency disorder areas. METHODS: Total number of subjects was 131. Analysis of serum TSH, T3, fT3, T4, and fT4 levels was done using ELISA. Polymorphism of Thr92Ala was analyzed by PCR-RFLP method. RESULTS: The results showed that the frequencies of the genotypes Thr92Ala were AA 16.79%, AG 41.22%, and GG 41.99%, whereas the allele frequency A 37.5% and G 62.5% (p HWE = 0.171). In this study, we found no differences of TSH and thyroid hormone level between group of each allel. Mean of TSH and thyroid hormone level was on normal range. CONCLUSION: This D2 polymorphism is associated with fT4 levels rather than fT3 but not statistically significant. Heterozygous alleles at D2 AG have higher TSH levels compared with homozygous alleles.

A study on normalization of hypothyroxinemia in neonates below 34 weeks of gestation

Objectives: The aim of the study was to estimate the time required for normalization of hypothyroxinemia of prematurity in neonates below 34 weeks of gestation. Material and Methods: A retrospective study was conducted in neonates born below 34 weeks of gestation, between January 2015 and December 2016. Data were collected on free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels, tested on days 3, 14, 28, and 42. Gestational age, birth weight, use of antenatal steroids, mechanical ventilation, and various preterm morbidities, along with development at 18 months of corrected age, were comparatively analyzed in neonates with and without hypothyroxinemia. The median time for normalization of fT4 in all these variables was estimated. Results: On day 3, low fT4 was noted in 69 (37.7%) out of 183 neonates born below 34 weeks of gestation; all had normal TSH levels. Hypothyroxinemia showed statistically significant association with gestational age, birth weight, antenatal steroid use, respiratory distress syndrome, invasive ventilation, shock, sepsis, patent ductus arteriosus (PDA), anemia during stay in neonatal intensive care unit, and development at 18 months. Median time for normalization was 14 days in most of the neonates, and 28 days in those with &lt;28 weeks of gestational age, weight of &lt;1000 g and with shock, anemia, and PDA. Two infants with hypothyroxinemia received therapy with levothyroxine at 6 weeks for a short duration, as TSH was high. Conclusion: Hypothyroxinemia of prematurity takes 14–28 days to normalize based on maturity, weight, and illnesses. This study recommends serum fT4 testing at 2 weeks of life, provided congenital hypothyroidism was ruled out by 3–4 days of life, using direct blood spot card metabolic screening.

Serum testosterone mirrors inflammation parameters in females hospitalized with COVID-19.

While low testosterone (T) was described as a predictor of unfavorable coronavirus-disease 19 (COVID-19) outcome in men, data concerning the role of T in women with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are scant and limited to small cohorts. This study investigated the relationship between serum T values and outcomes of COVID-19 in a large female hospitalized cohort. One-hundred-sixty-eight adult women (median age 77, range 18-100years; 154 in post-menopause) hospitalized for COVID-19 were assessed for PaO2/Fio2 ratio, serum T and inflammatory parameters. Median duration for hospital stay was 14.2days (range 1-115) with overall mortality of 26% (n = 44). Subjects who died were significantly older (p < 0.001), had significantly more comorbidities (p = 0.015) and higher serum T (p = 0.040), white blood cells (p = 0.007), c-reactive protein (CRP; p < 0.001), interleukin-6 (IL-6; p < 0.001), procalcitonin (PCT; p < 0.001), lactate dehydrogenase (LDH; p = 0.001), D-dimer (p = 0.035), fibrinogen (p = 0.038) and lower serum free-triiodothyronine (FT3; p < 0.001) and luteinizing hormone (LH; p = 0.024) values. In post-menopausal women, significant associations were observed between T levels and serum CRP (rho: 0.23; p = 0.002), IL-6 (rho: 0.41; p < 0.001), LDH (rho: 0.34; p < 0.001), D-Dimer (rho: 0.21; p = 0.008), PCT (rho: 0.26; p = 0.001) and HDL cholesterol (rho: - 0,22, p = 0.008). In multivariate regression analyses, serum T maintained the significant association with mortality after correction for age, coexistent comorbidities and serum LH and FT3, whereas it was lost after correction for inflammatory parameters. In females, high serum T levels might be a mirror of inflammatory phenotype and worse COVID-19 course.

ODP460 Age- and sex- specific reference ranges for serum thyrotropin (TSH), free T4 and free T3 levels: Significant effects on the definition of subclinical dysfunction

Abstract Introduction Consistent reference ranges of serum TSH, FT4 and FT3 levels without consideration of age and sex have been used to evaluate thyroid function. However, based on the recent development of highly sensitive assays of these hormones, subtle differences significantly affect the diagnosis, especially when diagnosing subclinical dysfunction, which affects more than 5% of the population. In the present study, we investigated the age- and sex- differences in these hormone levels using two different kits. Methods A total of 14,860 subjects for the Siemens kit and 6,604 subjects for the Abbot kit who underwent annual health check-ups at Takasaki Hidaka Hospital were included. Exclusion criteria comprised a history of thyroid disease, steroid use, renal failure or liver cirrhosis. All samples were measured at 8–9: 00 AM after overnight fasting. Results Regarding serum TSH levels in men, the median of subjects in their 30's was 1.4 mIU/L, the 2.5th percentile was 0.4, and the 97.5th percentile was 3.7 with the Siemens kit. These values in subjects in their 60's were 1.6, 0.5, and 5.7, respectively. They gradually but significantly increased with age based on both kits. Similarly in women, the serum TSH levels gradually increased, particularly with the Siemens kit, and the levels in women were higher than those in men. The median serum FT4 level in men in their 30's was 1.3 ng/dL (1. 0-1.7) and that in those in their 60's was 1.2 (1. 0-1.6) with the Siemens kit. The levels in men gradually but significantly decreased with age, but those in women were lower than those in men and remained consistent with age. Regarding serum FT3 levels in men, they were significantly higher than those in similarly aged women, and also gradually but significantly decreased with age; men in their 30's: 3.37 pg/mL (2.68-3.99), 60's: 3.15 (2.46-3.76) with the Abbot kit. Discussion The serum TSH level is highly sensitive to slight changes in the serum level of thyroid hormones even within the normal ranges; therefore, we diagnose subclinical hypothyroidism and hyperthyroidism using serum TSH levels. Many investigators have discussed the effects of subclinical dysfunction on lipid metabolism, osteoporosis, and cognitive mental diseases, and medications to normalize thyroid hormone levels. As there are significant differences in serum TSH, FT4, and FT3 levels according to age and sex, the age- and sex- dependent normal ranges should be used to precisely evaluate thyroid function and decide clinical therapies. Presentation: No date and time listed

ODP479 Equilibrium Dialysis ID-LC/MS/MS Procedure for Routine Measurement of Free Thyroxine in Serum

Abstract Free thyroxine (FT4) test is essential for diagnosis of thyroid diseases. Most FT4 tests used in patient care are immunoassays (IAs). However, concerns about the accuracy of FT4 IAs have been raised in the clinical laboratory community. Reference measurement procedure (RMP) for FT4 based on well-defined equilibrium dialysis (ED) of serum has been established and are well recognized. While FT4 RMP is highly accurate and precise, it is not intended for routine clinical use. Our aim is to develop an ED-based FT4 assay that is traceable to the RMP and suitable for routine measurements such as investigations in epidemiologic studies. The described assay is based on ED-LC-MS/MS. FT4 in serum was isolated from protein-bound T4 in serum according to the CLSI C45-A guideline. FT4 levels achieved equilibrium in a commercially available micro-ED plate after 18 hours. The dialysate was collected and spiked with internal standard (13 C 6 -T4). The IRMM-468 certified primary reference material (JRC, Belgium) of T4 was used for assay calibration. FT4 in dialysate was extracted with ISOLUTE-96-well C18 SPE plates (Biotage) before LC-MS/MS analysis. T4 could be resolved from Triiodothyronine (T3), reverse triiodothyronine (rT3), and other interferences in the dialysate on a C18 UPLC column with an elution time of less than 8 min. Selective reaction monitoring in positive electrospray ionization mode was used for detection. The measuring range covered 1-100 pg/mL of FT4. The assay sensitivity allowed detection of 0.5 pg/mL FT4, which is sufficient for detection of FT4 in normal and hypothyroid patient samples. The difference of this method to the CDC FT4 RMP was within ±5%. The imprecision of the routine assay, evaluated over four different days, was less than 10% CV. The slopes of calibration curves in dialysate matrix and water were comparable with each other indicating no significant matrix effect on FT4 quantification. The use of micro-ED plates in combination with an automated liquid handling system allows for effective automation of the procedure. The stability of T4 calibrator stock and working solutions were confirmed at various conditions. Currently, a comprehensive comparison study is underway between the newly developed routine method and the CDC FT4 RMP. The described routine FT4 assay can significantly improve throughput. The sensitivity, precision, and accuracy are suitable for routine FT4 measurements in clinical laboratories and conducting large epidemiologic studies. Applying this FT4 routine method to generate population data will support the use of standardized FT4 measurements and to address data needs on FT4 in general population. Presentation: No date and time listed

ODP478 Effects of peripheral iodothyronine deiodinases on thyroid hormone economy: Insights from the overexpressing mice

Abstract Background In peripheral tissues, triiodothyronine (T3) production and consequent thyroid hormone actions are mainly regulated by iodothyronine deiodinases (DIOs) classified into 3 types: D1, D2, and D3. Although thyroid hormone economy in the DIO-deficient mice and patients carrying genetic variants of DIOs was well clarified, a condition of DIOs upregulation was not enough elucidated. We aimed to investigate effects of peripheral DIOs on thyroid hormone economy and consequent thyroid hormone action using novel DIO-overexpressing mice that were not yet generated. Methods We cloned coding sequences of human DIOs with FLAG-tag and HiBiT-tag sequences into a pcDNA3.1 vector. To obtain full-length proteins, we modified these vectors by cloning selenocysteine insertion sequence of each DIO (SECIS vectors). Western blot analyses and HiBiT lytic assay using HEK293T cells revealed that SECIS vectors expressed full-length proteins with substantial activity. Subsequently, in vivo transfections of pLIVE-based SECIS vectors into male C57BL/6J mice were performed by hydrodynamic gene delivery to generate mice overexpressing DIOs (D1, D2, and D3 mice). Results First, we verified that DIOs were successfully overexpressed in the livers using HiBiT lytic assay as well as RT-PCR. Analyses of multiple organs of D3 mice assured that full-length protein was not significantly expressed in the heart, the kidney, and the skeletal muscle. RT-PCR analyses also suggested that the pituitary glands and the thyroid glands were not transfected. We evaluated thyroid hormone economy of DIO-overexpressing mice compared to Empty mice transfected with pLIVE-Empty vector. D1 mice did not have changes in serum thyroid hormone levels, whereas D2 mice had higher serum fT3 levels. Clearer changes were found in D3 mice. They had hypothyroidism with higher serum rT3 levels. Correspondingly, in their livers, rT3 concentration was higher and T3-responsive genes were downregulated. We elucidated by adding the cohort with levothyroxine (LT4) administration because DIO-overexpressing mice had liver T4 insufficiency probably due to consumption by DIOs. Comparisons between the DIO-overexpressing mice with and without LT4 administration revealed that D2 mice presented upregulation of T3-responsive genes by LT4 administration distinct from Empty mice. Conclusions We generated DIO-overexpressing mice that expressed human DIOs predominantly in the liver. They provided physiological evidence to integrate the phenotypes of the knockout mice and specific clinical situations. D2 mice seemed to recruit T3 into the circulation as well as in the liver. D3 mice had an overt phenotype characterized by consumptive hypothyroidism. In addition, D3 mice are expected to be a novel hypothyroidism model that does not involve disruption of thyroidal hormone secretion. DIO-overexpressing mice can be generated by single injections of plasmid vectors of interest and can contribute to progress in the field of thyroid hormone economy and action. Presentation: No date and time listed

OR19-5 Dissecting Thyroidal Pathways Activated by PD-L1 Blockade Identifies New Mechanisms for Thyroiditis Triggered by Immune Checkpoint Inhibitors

Abstract Programmed death-ligand 1 (PD-L1) is a strong immunosuppressor that inhibits T-cell activation by binding to its receptor (PD-1) on T-cells. Blocking the PD-L1/PD-1 interaction by monoclonal antibodies (mAbs) is an effective therapy for several cancers via activation of T-cells. Destructive thyroiditis and hypothyroidism often develop during anti-PD-L1 (αPD-L1) therapy but the pathogenic mechanisms are not known. We evaluated in vivo, the role of PD-L1 and its interactions with inflammatory triggers in the development of autoimmune thyroiditis (AIT). NOD.H-2h4 mice were treated with either αPD-L1 or isotype control (CTR) for two weeks and AIT evaluated after six weeks. αPD-L1 treated mice showed significantly higher Abs (p = 6×10e-4) and T-cell responses (p = 0.02) to thyroglobulin (Tg) compared with CTR mice. Serum fT4 levels were lower (p = 0.01) and TSH higher (p = 0.05) in αPD-L1 treated vs. CTR mice. Seven of the eight αPD-L1 treated mice (and none of the CTR mice) developed thyroid lymphocytic infiltration characterized by the presence of the CD4+, CD8+, FoxP3+ T- cells and B220+ B- cells. To gain insight into the pathways regulated by PD-L1 in the thyroid we assessed gene expression in the thyroid of αPD-L1 treated mice using RNA-seq. PD-L1 blockade was associated with upregulation of pathways of lymphocyte activation (p = 1.3×10e-5), lymphocyte proliferation (p = 2×10e-5), chemotaxis (p = 3.8×10e-12), and inflammatory response (p = 7.9×10e-7). Specifically, blocking PD-L1 was associated with upregulation of cytokine/chemokine genes that have a critical role in Th1 differentiation: IFNγ, IL-12, IL-15, CCL1 to CCL5, CD300, CXCL10, CXCL11. Ingenuity Pathway Analysis identified IFNγ and TNF as the top regulators of these activated gene networks. These results indicate that blockade of PD-L1 in thyroid promoted the Th1 mediator, IFNγ, inducing activation and proliferation of thyroidal CD4+ and CD8+ T cells, triggering thyroid tissue damage and AIT. Since PD-L1 mediates immune responses to inflammatory stressors (e.g. viral infections), we evaluated PD-L1 interaction with a known inflammatory trigger of AIT, interferon alpha (IFNα). Treatment with αPD-L1 + IFNα accelerated AIT in NOD.H-2h4 mice that developed high Tg Ab and T-cell responses and thyroidal lymphocytic infiltration only two weeks after treatment. Moreover, thyroiditis was more severe in mice receiving αPD-L1 + IFNα than αPD-L1 alone, manifesting by higher T-cell responses (p = 5×10e-3), and significantly more profound hypothyroidism. These results suggest that PDL-1 has a protective role in the thyroid against inflammatory stressors, and that its blockade exposes the thyroid to inflammatory damage. Therefore, in patients undergoing αPD-L1 therapy, inflammatory conditions (e.g. infections) can be a "second hit" that accelerates the onset of thyroiditis and augments thyroidal inflammation. Presentation: Monday, June 13, 2022 12:00 a.m. - 12:15 a.m.

Association of COVID-19 vaccination before conception with maternal thyroid function during early pregnancy: A single-center study in China.

Despite the high vaccination coverage, potential COVID-19 vaccine-induced adverse effects, especially in pregnant women, have not been fully characterized. We examined the association between COVID-19 vaccination before conception and maternal thyroid function during early pregnancy. We conducted a retrospective cohort study in Shanghai, China. A total of 6979 pregnant women were included. Vaccine administration was obtained from electronic vaccination records. Serum levels of thyroid hormone were measured by fluorescence and chemiluminescence immunoassays. Among the 6979 included pregnant women, 3470 (49.7%) received at least two doses of an inactivated vaccine. COVID-19 vaccination had a statistically significant association with both maternal serum levels of free thyroxine (FT4) and thyroid stimulating hormone (TSH). Compared with unvaccinated pregnant women, the mean FT4 levels were lower in pregnant women who had been vaccinated within 3 months before the date of conception by 0.27 pmol/L (β = -0.27, 95% confidence interval [CI], -0.42, -0.12), and the mean TSH levels were higher by 0.08 mIU/L (β = 0.08, 95% CI, 0.00, 0.15). However, when the interval from vaccination to conception was prolonged to more than 3 months, COVID-19 vaccination was not associated with serum FT4 or TSH levels. Moreover, we found that COVID-19 vaccination did not significantly associate with maternal hypothyroidism. Our study suggested that vaccination with inactivated COVID-19 vaccines before conception might result in a small change in maternal thyroid function, but this did not reach clinically significant levels.

Exploration of RCBF and Metabolic Changes in the Brain Functional Areas of Patients with Hypothyroidism by ASL and MRS Techniques.

Objective To study the regional cerebral blood flow (rCBF) in important brain functional areas and the metabolic levels of these brain functional areas in patients with primary hypothyroidism by using arterial spin labeling (ASL) and magnetic resonance spectroscopy (MRS) techniques to explain the possible causes of brain dysfunction in patients with primary hypothyroidism. Methods Twenty-five patients with primary hypothyroidism (newly diagnosed and not treated) who were treated in the endocrinology department of our hospital were selected as the research group, and 25 healthy patients with normal thyroid function who came to our hospital during the same period with matched gender and age were selected as the control group. ASL and MRS techniques were used to detect and calculate regional cerebral blood flow (rCBF) in the frontal lobe, hippocampus, and posterior cingulate gyrus, as well as N-acetylaspartate/creatine (NAA/Cr), choline/creatine (Cho) in the brain/Cr, and inositol/creatine (mI/Cr) ratio. The correlations between metabolite ratios measured by rCBF, MRS, and serum TSH, FT3, and FT4 levels were analyzed. Results Compared with the control group, the rCBF in the frontal lobe, hippocampus, and posterior cingulate gyrus of the dominant hemisphere of the hypothyroid patients in the study group decreased significantly (P < 0.05). The comparison of metabolite ratios showed that compared with the control group, the NAA/Cr ratio of the frontal lobe and posterior cingulate gyrus of the study group was significantly decreased, and the Cho/Cr ratio of the posterior cingulate gyrus of the study group was significantly increased. The MI/Cr ratio of the hippocampus was significantly decreased (all P values < 0.05). Correlation analysis showed that rCBF and NAA/Cr in posterior cingulate gyrus were significantly negatively correlated with serum TSH levels (P < 0.05). Conclusion The changes of rCBF and metabolite ratios in the frontal lobe, hippocampus, and posterior cingulate gyrus of patients with primary hypothyroidism can be detected using ASL and MRS techniques. The changes of rCBF and metabolite ratio and their negative correlation with serum TSH level are helpful to explain the causes of brain dysfunction in patients with primary hypothyroidism.

Exploring the endocrine disrupting potential of lead through benchmark modelling – Study in humans

Exposure to low levels of a toxic metal lead (Pb) affects human health, and its effect as an endocrine disruptor has been reported. However, the precise role of Pb in endocrine health is still unclear because no dose-response relationship has been established for such an effect. The present study aimed to examine blood Pb levels (BLLs) in relation to serum levels of free triiodothyronine (fT3), free thyroxine (fT4), thyroid stimulating hormone (TSH), and insulin in 435 nonoccupationally exposed Serbian subjects (218 women, 217 men, 18–94 years of age, mean age 48). In addition, benchmark dose (BMD) values were calculated for these endocrine endpoints using the PROAST 70.1 software. An explicit dose-response dependency between BLL and TSH, fT3, fT4, testosterone, and insulin serum levels was evident from BMD modelling. The results support the positive association between BLLs and serum insulin levels, with observed dose-response and calculated BMD values of 1.49 and 0.74 μg Pb/dL in males and females, respectively. Collectively, our findings reported potential endocrine-disrupting effects of Pb at the environmental exposure levels experienced by current Serbian population. They also strengthen the notion that the blood Pb threshold level for an endocrine effect is low.

Opposite Effect of Thyroid Hormones on Oxidative Stress and on Mitochondrial Respiration in COVID-19 Patients.

Background: Thyroid hormones (TH)s are master regulators of mitochondrial activity and biogenesis. Nonthyroidal illness syndrome (NTIS) is generally considered an adaptative response to reduced energy that is secondary to critical illness, including COVID-19. COVID-19 has been associated with profound changes in the cell energy metabolism, especially in the cells of the immune system, with a central role played by the mitochondria, considered the power units of every cell. Infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects and alters mitochondrial functions, both to influence its intracellular survival and to evade host immunity. Aim of the study: This study was undertaken to analyze the oxidative balance and mitochondrial respiration in COVID-19 patients with and without NTIS to elucidate the role that thyroid hormones (TH)s play in this context. Methods: In our cohort of 54 COVID-19 patients, admitted to our University Hospital during the COVID-19 pandemic, we evaluated the generation of reactive oxygen species (ROS) by measuring the serum levels of derivatives of reactive oxygen metabolites (dROMs), and we analyzed the antioxidant capacity by measuring the serum biological antioxidant potential (BAP). We then analyzed the mitochondrial respiration in peripheral blood mononuclear cells (PBMC)s of 28 of our COVID-19 patients, using the seahorse instrument (Agilent). Results were correlated with the serum levels of THs and, in particular, of FT3. In addition, the role of T3 on bioelectrical impedance analysis (BIA) and mitochondrial respiration parameters was directly evaluated in two COVID-19 patients with NTIS, in which treatment with synthetic liothyronine (LT3) was given both in vivo and in vitro. Results: In our COVID-19 patients with NTIS, the dROMs values were significantly lower and the BAP values were significantly higher. Consequently, the oxidative stress index (OSi), measured as BAP/dROMs ratio was reduced compared to that observed in COVID-19 patients without NTIS, indicating a protective role exerted by NTIS on oxidative stress. In our COVID-19 patients, the mitochondrial respiration, measured in PBMCs, was reduced compared to healthy controls. Those with NTIS showed a reduced maximal respiratory capacity and a reduced proton leak, compared to those with normal FT3 serum values. Such lowered mitochondrial respiratory capacity makes the cells more vulnerable to bioenergetic exhaustion. In a pilot study involving two COVID-19 patients with NTIS, we could reinforce our previous observation regarding the role of T3 in the maintenance of adequate peripheral hydroelectrolytic balance. In addition, in these two patients, we demonstrated that by treating their PBMCs with LT3, both in vitro and in vivo, all mitochondrial respiration parameters significantly increased. Conclusions: Our results regarding the reduction in the serum levels of the reactive oxygen species (ROS) of COVID-19 patients with NTIS support the hypothesis that NTIS could represent an adaptative response to severe COVID-19. However, beside this beneficial effect, we demonstrate that, in the presence of an acute reduction of FT3 serum levels, the mitochondrial respiration is greatly impaired, with a consequent establishment of a hypoenergetic state of the immune cells that may hamper their capacity to react to massive viral infection.

Effect of Bushen Antai recipe on pyroptosis mechanism of subclinical hypothyroidism decidual cells in early pregnancy.

Subclinical hypothyroidism (SH) is common during pregnancy. It is not clear whether decidual cells in SH undergo pyroptosis during pregnancy. This study aimed to investigate the possible mechanism of Bushen Antai recipe (BAR) in the treatment of SH in early pregnancy and the relationship between SH during pregnancy and decidual cell pyroptosis through a rat model. A total of 60 female rats were divided into control group, model group, levothyroxine (L-T4) group, low-dose BAR group (6 g/kg), medium-dose BAR group (12 g/kg), and high-dose BAR group (24 g/kg). The control group underwent pseudothyroidectomy, while the remaining groups established nonpregnant SH rat models. Except for the blank control group, rats were successfully established with SH models during pregnancy. The control group and the model group were treated with saline or BAR. The animals were sacrificed 12 hours after the last administration. The levels of serum thyroid-stimulating hormone (TSH), free thyroxine (FT4), interleukin-1β (IL-1β), and interleukin-18 (IL-18) were detected by enzyme-linked immunosorbent assay (ELISA). Western blot was used to detect the expression of decidual nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome, Caspase-1, and porin family proteins. There was no significant difference in serum FT4 among groups (P>0.05). Compared with the control group, serum TSH, IL-1β, IL-18, and NLRP3, Caspase-1, and gasdermin D (GSDMD) proteins in the decidua of the model group were significantly increased (P<0.05). Compared with the model group, the L-T4 group and the high-dose BAR group could significantly decrease the levels of serum TSH, IL-1β, IL-18, and NLRP3, Caspase-1, and GSDMD in decidual tissue (P<0.05). The medium dose of BAR could significantly decrease the levels of TSH, NLRP3, Caspase-1, and GSDMD (P<0.05), and the low dose group of BAR significantly decreased the levels of TSH, NLRP3, and GSDMD (P<0.05). Among them, the high-dose group of BAR had the best reducing effect on IL-18, NLRP3, Caspase-1, and GSDMD. The decidual cells of SH rats in early pregnancy underwent pyroptosis with a high inflammatory response. BAR could improve TSH level in SH during pregnancy, inhibit decidual cell pyroptosis, and reduce the expression of inflammatory factors.

The longitudinal effect of oxcarbazepine on thyroid function in children and adolescents with epilepsy.

Thyroid hormone abnormalities have been linked to antiseizure medications (ASMs). Oxcarbazepine is considered safer than carbamazepine because it induces the hepatic cytochrome P450 metabolic enzymes less than the carbamazepine does. However, limited data exist for the influence of oxcarbazepine on thyroid function in children and adolescents. The objective of this study was to determine the effect of oxcarbazepine on thyroid function in these patients. A total of 162 pediatric patients with epilepsy who started oxcarbazepine for the first time between April 2003 and May 2020 were enrolled. The longitudinal effects of oxcarbazepine for thyroid functions were confirmed using general estimating equations. Serum triiodothyronine (T3), thyroxine (T4), and free thyroxine (fT4) levels decreased significantly during 5 years of follow-up (all p's < .001). In particular, T3 and fT4 levels were reduced steeply in the first 2 years of oxcarbazepine treatment. There was no significant change in thyroid-stimulating hormone during oxcarbazepine treatment. Serum T3, T4, and fT4 levels decreased significantly during oxcarbazepine use, and this change was maintained during the treatment period. In patients receiving oxcarbazepine, it is recommended that periodic thyroid function testing should be performed, especially within the first 2 years after starting this ASM. Our results indicate that oxcarbazepine-induced hypothyroidism does not appear to be accompanied by a significant increase in TSH, and consequently might be missed if TSH alone is monitored as a measure of thyroid dysfunction.