Decreased blood vessel density and endothelial cell subset dynamics during ageing of the endocrine system.

Age-associated alterations of the hormone-secreting endocrine system cause organ dysfunction and disease states. However, the cell biology of endocrine tissue ageing remains poorly understood. Here, we perform comparative 3D imaging to understand age-related perturbations of the endothelial cell (EC) compartment in endocrine glands. Datasets of a wide range of markers highlight a decline in capillary and artery numbers, but not of perivascular cells in pancreas, testis and thyroid gland, with age in mice and humans. Further, angiogenesis and ß-cell expansion in the pancreas are coupled by a distinct age-dependent subset of ECs. While this EC subpopulation supports pancreatic ß cells, it declines during ageing concomitant with increased expression of the gap junction protein Gja1. EC-specific ablation of Gja1 restores ß-cell expansion in the aged pancreas. These results provide a proof of concept for understanding age-related vascular changes and imply that therapeutic targeting of blood vessels may restore aged endocrine tissue function. This comprehensive data atlas offers over > 1,000 multicolour volumes for exploration and research in endocrinology, ageing, matrix and vascular biology.

The paradox of spring: Thyroid and glucocorticoid responses to cold temperatures and food availability in free living Carneddau ponies.

In seasonal environments, maintaining a constant body temperature poses challenges for endotherms. Cold winters at high latitudes, with limited food availability, create opposing demands on metabolism: upregulation preserves body temperature but depletes energy reserves. Examining endocrine profiles, such as thyroid hormone triiodothyronine (T3) and glucocorticoids (GCs), proxies for changes in metabolic rate and acute stressors, offer insights into physiological trade-offs. We evaluated how environmental conditions and gestation impact on faecal hormone metabolites (fT3Ms and fGCMs) from late winter to spring in a free-living population of Carneddau ponies. Faecal T3Ms were highest in late February and March, when temperatures were lowest. Then, fT3Ms concentrations decreased throughout April and were at the lowest in May before increasing towards the end of the study. The decline in fT3M levels in April and May was associated with warmer weather but poor food availability, diet diversity and diet composition. On the other hand, fGCM levels did not display a clear temporal pattern but were associated with reproductive status, where pregnant and lactating females had higher fGCM levels as compared to adult males and non-reproductive females. The temporal profile of fT3Ms levels highlights metabolic trade-offs in a changing environment. In contrast, the ephemeral but synchronous increase in fGCM concentrations across the population suggest a shared experience of acute stressors (i.e., weather, disturbance or social). This multi-biomarker approach can evaluate the role of acute stressors versus energy budgets in the context of interventions, reproduction, seasonality and environmental change, or across multiple scales from individuals to populations.

Association of thyroid function with non-alcoholic fatty liver disease in recent-onset diabetes.

BACKGROUND AND AIMS: Non-alcoholic fatty liver disease (NAFLD) has been linked to type 2 diabetes (T2D), but also to hypothyroidism. Nevertheless, the relationship between thyroid function and NAFLD in diabetes is less clear. This study investigated associations between free thyroxine (fT4) or thyroid-stimulating hormone (TSH) and NAFLD in recent-onset diabetes. METHODS: Participants with recent-onset type 1 diabetes (T1D, n = 358), T2D (n = 596) or without diabetes (CON, n = 175) of the German Diabetes Study (GDS), a prospective longitudinal cohort study, underwent Botnia clamp tests and assessment of fT4, TSH, fatty liver index (FLI) and in a representative subcohort 1 H-magnetic resonance spectroscopy. RESULTS: First, fT4 levels were similar between T1D and T2D (p = .55), but higher than in CON (T1D: p < .01; T2D: p < .001), while TSH concentrations were not different between all groups. Next, fT4 correlated negatively with FLI and positively with insulin sensitivity only in T2D (ß = -.110, p < .01; ß = .126, p < .05), specifically in males (ß = -.117, p < .05; ß = .162; p < .01) upon adjustments for age, sex and BMI. However, correlations between fT4 and FLI lost statistical significance after adjustment for insulin sensitivity (T2D: ß = -.021, p = 0.67; males with T2D: ß = -.033; p = .56). TSH was associated positively with FLI only in male T2D before (ß = .116, p < .05), but not after adjustments for age and BMI (ß = .052; p = .30). CONCLUSIONS: Steatosis risk correlates with lower thyroid function in T2D, which is mediated by insulin resistance and body mass, specifically in men, whereas no such relationship is present in T1D.

A Novel Transgenic Model to Study Thyroid Axis Activity in Early Life Stage Medaka.

Identifying endocrine disrupting chemicals in order to limit their usage is a priority and required according to the European Regulation. There are no Organization for Economic Co-operation and Development (OECD) test guidelines based on fish available for the detection of Thyroid axis Active Chemicals (TACs). This study aimed to fill this gap by developing an assay at eleuthero-embryonic life stages in a novel medaka (Oryzias latipes) transgenic line. This transgenic line expresses green fluorescent protein (GFP) in thyrocytes, under the control of the medaka thyroglobulin gene promoter. The fluorescence expressed in the thyrocytes is inversely proportional to the thyroid axis activity. When exposed for 72 h to activators (triiodothyronine (T3) and thyroxine (T4)) or inhibitors (6-N-propylthiouracil (PTU), Tetrabromobisphenol A (TBBPA)) of the thyroid axis, the thyrocytes can change their size and express lower or higher levels of fluorescence, respectively. This reflects the regulation of thyroglobulin by the negative feedback loop of the Hypothalamic-Pituitary-Thyroid axis. T3, T4, PTU, and TBBPA induced fluorescence changes with the lowest observable effect concentrations (LOECs) of 5 µg/L, 1 µg/L, 8 mg/L, and 5 mg/L, respectively. This promising tool could be used as a rapid screening assay and also to help decipher the mechanisms by which TACs can disrupt the thyroid axis in medaka.

Salivary iodine concentration in pregnant women and its association with iodine status and thyroid function.

PURPOSE: There have been no reports on the application of salivary iodine concentration (SIC) in evaluating iodine nutrition in pregnant women. This study aimed to clarify the relationship between SIC and indicators of iodine nutritional status and thyroid function during pregnancy, to investigate whether salivary iodine can be applied to the evaluation of iodine nutritional status in pregnant women, and to provide a reference basis for establishing a normal range of salivary iodine values during pregnancy. METHODS: Pregnant women were enrolled in the Department of Obstetrics, the people's hospital of Yuncheng Country, Shandong Province, from July 2021 to December 2022, using random cluster sampling. Saliva, urine, and blood samples were collected from pregnant women to assess iodine nutritional status, and venous blood was collected to determine thyroid function. RESULTS: A total of 609 pregnant women were included in this study. The median spot urinary iodine concentration (SUIC) was 261 µg/L. The median SIC was 297 µg/L. SIC was positively correlated with SUIC (r = 0.46, P < 0.0001), 24-h UIC (r = 0.30, P < 0.0001), 24-h urinary iodine excretion (24-h UIE) (r = 0.41, P < 0.0001), and estimated iodine intake (EII) (r = 0.52, P < 0.0001). After adjusting for confounders, there was a weak correlation between SIC and serum total iodine and serum non-protein-bound iodine (P = 0.02, P = 0.04, respectively). Pregnant women with a SIC < 176 µg/L had a higher risk of insufficient iodine status (OR = 2.07, 95% CI 1.35-3.19) and thyroid dysfunction (OR = 2.71, 95% CI 1.18-6.21) compared to those with higher SIC. Those having SIC > 529 µg/L were more likely to have excessive iodine status (OR = 2.82, 95% CI 1.81-4.38) and thyroid dysfunction (OR = 3.04, 95% CI 1.36-6.78) than those with lower SIC values. CONCLUSION: SIC is associated with urinary iodine concentration and thyroid function in pregnant women. SIC < 176 µg/L was associated with an increased risk for iodine deficiency and hypothyroxinemia, while SIC > 529 µg/L was related to excess and thyrotoxicosis. SIC can be used as a reference indicator for evaluating the iodine nutrition status of pregnant women, but it needs further investigation and verification. TRIAL REGISTRATION: NCT04492657(Aug 9, 2022).

The correlation between the thyroid function and urinary iodine/creatinine ratio of pregnant women attending a tertiary hospital in Beijing, China, during different trimesters.

OBJECTIVE: This study investigated the correlation between thyroid function and urinary iodine/creatinine ratio (UI/Cr) in pregnant women during different trimesters and explored potential influencing factors. METHODS: In this cross-sectional study, serum levels of thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), and UI/Cr were measured in 450 pregnant women. Correlations were analyzed using Pearson's correlation coefficient and multiple linear regression. Subgroup analyses were performed based on age, body mass index (BMI), parity, gestational age, education, occupation, and family history of thyroid disorders. RESULTS: UI/Cr was positively correlated with FT4 levels in the first and second trimesters, particularly in women with older age, higher BMI, multiparity, higher education, and employment. No significant correlations were found between UI/Cr and TSH or FT3 levels. CONCLUSION: UI/Cr is positively correlated with FT4 levels in early pregnancy, especially in women with certain risk factors. Regular monitoring of iodine status and thyroid function is recommended for pregnant women to ensure optimal maternal and fetal health.

Association between physical activity and thyroid function in American adults: a survey from the NHANES database.

OBJECTIVE: Physical activity (PA) is closely related to our lives, and the effects of PA on thyroid function have not been elucidated. METHODS: Using data from the National Health and Nutrition Examination Survey (NHANES) 2007-2012, we included 5877 participants and analyzed the associations of thyroid function with weekly physical activity (PAM, expressed in metabolic equivalents of task) and physical activity time (PAT) in American adults. Univariate and multivariate logistic analyses were used to demonstrate the associations of PAM and PAT with the primary outcome. Linear regression analysis was performed to determine the associations between thyroid biochemical indicators/diseases and PAM/PAT. RESULTS: Our study revealed noticeable sex differences in daily PA among the participants. The odds ratio of the fourth versus the first quartile of PAM was 3.07 (confidence interval, CI [1.24, 7.58], p = 0.02) for overt hypothyroidism, 3.25 (CI [1.12, 9.45], p = 0.03) for subclinical hyperthyroidism in adult men. PAT in the range of 633-1520 min/week was found to be associated with the occurrence of subclinical hyperthyroidism [p < 0.001, OR (95% CI) = 5.89 (1.85, 18.80)], PAT of the range of > 1520 min/week was found to be associated with the occurrence of overt hypothyroidism [p < 0.001, OR (95% CI) = 8.70 (2.80, 27.07)] and autoimmune thyroiditis (AIT) [p = 0.03, OR (95% CI) = 1.42 (1.03, 1.97)] in adult men. When PAM < 5000 MET*minutes/week or PAT < 1000 min/week, RCS showed an L-shaped curve for TSH and an inverted U-shaped curve for FT4. The changes in FT3 and TT3 in men were linearly positively correlated with PAM and PAT, while TT4 is linearly negatively correlated. CONCLUSION: The amount of daily physical activity of American adults is strongly associated with changes in thyroid function, including thyroid hormone levels and thyroid diseases. Thyroid hormone levels were varied to a certain extent with changes in PAM and PAT.

Relationship of Thyroid Volume and Function with Ankle-Brachial Index, Toe-Brachial Index, and Toe Pressure in Euthyroid People Aged 18-65.

Background and Objectives: The interrelationship between thyroid function and the state of the cardiovascular system has been investigated both in preclinical and human studies. However, it remains unclear whether there is any association between thyroid hormones and features of subclinical cardiovascular dysfunction in euthyroid patients. Material and Methods: This study involved 45 people (females: 57.8%) with no thyroid disease who, during planned hospitalization, underwent thyroid ultrasound, determination of biochemical parameters of thyroid function, and measurement of ankle-brachial index (ABI) and toe-brachial index (TBI). People with signs of acute illness or a deterioration of their health were excluded. Results: Significant correlations were found between free triiodothyronine (FT3) and several parameters of both ABI (R = 0.347; p = 0.019 for the mean ABI taken from right side and left side values) and TBI (R = 0.396; p = 0.007 for the mean TBI taken from right side and left side values), as well as the maximal toe pressure (TP) taken from right side and left side values (R = 0.304; p = 0.045). Thyrotropin (TSH) was shown to be significantly correlated only with the maximal TBI value (taken from right side and left side values) (R = 0.318; p = 0.033), whereas free thyroxin (FT4) was shown to be significantly correlated only with the minimal TBI value (taken from right side and left side values) (R = 0.381; p = 0.01). Thyroid volume (TV) was shown to be correlated with TP (R = 0.4; p = 0.008 for the mean TP taken from right side and left side values) and some parameters of TBI value (R = 0.332; p = 0.028 for the mean TBI taken from right side and left side values), but no significant correlations were found between TVand ABI parameters. Patients with a mean ABI value ≤ 1.0 or a mean TBI value ≤ 0.75 have lower TSH, FT3, FT4, and TV than the rest of the study population, but the difference was statistically significant only for FT3. Conclusions: Even in a population of euthyroid patients with no diagnosed thyroid disease, there are some significant correlations between the volume and function of the thyroid gland and the selected features of subclinical cardiovascular dysfunction such as ABI and TBI.

Retrospective Cross-Sectional Study of the Relationship of Thyroid Volume and Function with Anthropometric Measurements, Body Composition Analysis Parameters, and the Diagnosis of Metabolic Syndrome in Euthyroid People Aged 18-65.

Background and Objectives: The thyroid is a key endocrine gland for the regulation of metabolic processes. A body composition analysis (BCA) is a valuable complement to the assessment of body mass index, which is derived only from body weight and height. This cross-sectional retrospective study aimed to investigate the relationships between thyroid volume (TV) and thyroid function parameters, anthropometric measurements, BCA parameters, and the presence of metabolic syndrome (MetS) in adults without clinically overt thyroid disease. Material and Methods: This study involved 45 people (females: 57.8%; MetS: 28.9%) hospitalized for planned diagnostics without signs of acute illness or a deterioration of their health and without thyroid disease, who underwent thyroid ultrasound scans, biochemical tests to assess their thyroid function, MetS assessments, anthropometric measurements, and BCAs using the bioelectrical impedance method. Results: The TV was significantly larger in people with MetS compared to people without MetS. The TV was significantly higher and the serum thyrotropin (TSH) concentration was significantly lower in overweight and obese people than in normal and underweight people. The free triiodothyronine (FT3) serum concentration and TV were correlated with waist circumference and some parameters of the BCA, and the FT3 concentration was also correlated with the body mass index, waist-hip ratio, and waist-height ratio. No significant correlations were found between the FT4 and TSH and the results of the anthropometric and BCA measurements. Conclusions: Even in a population of euthyroid patients without clinically overt thyroid disease, there were some significant relationships between the volume and function of the thyroid gland and the results of their anthropometric parameters, BCAs, and the presence of MetS features.

Age-Related Features of the Function of the Hypothalamic-Pituitary-Thyroid (HPT) Axis in Nonhuman Primates under Constant Lighting.

We studied the features of the functioning of the hypothalamic-pituitary-thyroid (HPT) axis under conditions of constant (4 weeks) lighting (LED lamps intended for office and residential premise) on a translational model of young adult and old female rhesus monkeys, in particular taking into account their behavior. Constant lightning had no significant effect on the levels of thyroid-stimulating hormone, thyroxine, and triiodothyronine under basal conditions in all animals, regardless of age and behavioral characteristics, but induced a decrease in thyroid function under conditions of its activation with thyrotropin-releasing hormone, mainly in old animals.

[Investigation of influencing factors and reference ranges for thyroid function in hospitalized preterm infants at the age of 7 days]. / 7æ—¥é¾„ä½é™¢æ—©äº§å„¿ç”²çŠ¶è ºåŠŸèƒ½å½±å“å› ç´ åŠå‚è€ƒå€¼èŒƒå›´æŽ¢è®¨.

OBJECTIVES: To investigate the influencing factors and reference ranges for thyroid function in preterm infants at the age of 7 days, with the aim of avoiding unnecessary clinical reexamination and intervention. METHODS: A retrospective analysis was performed for the data of 685 preterm infants from January 2020 to January 2023. According to gestational age and birth weight, they were divided into a high-risk group (gestational age <34 weeks or birth weight<2 000 g; 228 infants) and a low-risk group (gestational age ≥34 weeks and birth weight ≥2 000 g;457 infants). The influencing factors for thyroid function were analyzed, and 95% reference range was calculated. RESULTS: Gestational age, birth weight, birth season, sex, and assisted reproduction were the influencing factors for thyroid function (P<0.05). For the preterm infants in the high-risk group, the reference ranges of free triiodothyronine (FT3), free thyroxine (FT4), total triiodothyronine (TT3), total thyroxine (TT4), and thyroid stimulating hormone (TSH) were 2.79-5.40 pmol/L, 8.80-25.64 pmol/L, 0.80-2.15 nmol/L, 50.06-165.09 nmol/L, and 0.80-18.57 µIU/mL, respectively. For those in the low-risk group, the reference ranges of these indicators were 3.08-5.93 pmol/L, 11.17-26.24 pmol/L, 1.02-2.27 nmol/L, 62.90-168.95 nmol/L, and 0.69-13.70 µIU/mL, respectively. FT3, FT4, TT3, and TT4 were positively correlated with gestational age (P<0.05); FT3, FT4, TT3, and TT4 were positively correlated with birth weight (P<0.05); TSH was negatively correlated with birth weight (P<0.05). CONCLUSIONS: Thyroid function in preterm infants at the age of 7 days is affected by the factors such as gestational age and birth weight, and the reference ranges of thyroid function in preterm infants at the age of 7 days should be established based on gestational age and birth weight.

Gestational thyroid hormone concentrations and risk of attention-deficit hyperactivity disorder in the Norwegian Mother, Father and Child Cohort Study.

BACKGROUND: Maternal thyroid function plays an important role in foetal brain development; however, little consensus exists regarding the relationship between normal variability in thyroid hormones and common neurodevelopmental disorders, such as attention-deficit hyperactivity disorder (ADHD). OBJECTIVE: We sought to examine the association between mid-pregnancy maternal thyroid function and risk of clinically diagnosed ADHD in offspring. METHODS: We conducted a nested case-control study in the Norwegian Mother, Father and Child Cohort Study. Among children born 2003 or later, we randomly sampled singleton ADHD cases obtained through linkage with the Norwegian Patient Registry (n = 298) and 554 controls. Concentrations of maternal triiodothyronine (T3), thyroxine (T4), T3-Uptake, thyroid-stimulating hormone (TSH) and thyroid peroxidase antibody (TPO-Ab) were measured in maternal plasma, collected at approximately 17 weeks' gestation. Indices of free T4 (FT4i) and free T3 (FT3i) were calculated. We used multivariable adjusted logistic regression to calculate odds ratios and accounted for missing covariate data using multiple imputation. We used restricted cubic splines to assess non-linear trends and provide flexible representations. We examined effect measure modification by dietary iodine and selenium intake. In sensitivity analyses, we excluded women with clinically significant thyroid disorders (n = 73). RESULTS: High maternal T3 was associated with increased risk of ADHD (5th vs 1st quintile odds ratio  2.27, 95% confidence interval 1.21, 4.26). For FT4i, both the lowest and highest quintiles were associated with an approximate 1.6-fold increase in risk of ADHD, with similar trends found for T4. The FT4i association was modified by dietary iodine intake such that the highest risk strata were confined to the low intake group. CONCLUSIONS: Both high and low concentrations of maternal thyroid hormones, although within population reference ranges, increase the risk of ADHD in offspring. Increased susceptibility may be found among women with low dietary intake of iodine and selenium.

Thyroid function, glycemic control, and diabetic nephropathy in patients with type 2 diabetes over 24 months: prospective observational study.

BACKGROUND: The higher prevalence of thyroid dysfunction in type 1 diabetes patients has been well established, whereas it is a matter of debate whether that is also observed in type 2 diabetes patients. This study was conducted to reveal whether higher prevalence of thyroid dysfunction is observed in patients with type 2 diabetes. METHODS: We examined thyroid functions and thyroid autoantibodies in 200 patients with type 2 diabetes and 225 controls, with 24 months follow up for those with type 2 diabetes. RESULTS: Serum free triiodothyronine (fT3) levels and fT3/free thyroxine (fT4) ratio were significantly lower, while fT4 levels were significantly higher in patients with type 2 diabetes. The number of patients with thyroid dysfunction or patients positive for thyroid autoantibodies were not different between the two groups. The fT3/fT4 ratio was positively and negatively correlated with serum c-peptide and HbA1c levels, respectively, suggesting that the difference can be attributable to insulin resistance and diabetic control. In the follow-up observation, we found no significant correlation between basal thyrotropin (TSH), fT3, fT4 or fT3/fT4 ratio with the amounts of changes of HbA1c levels at 12 or 24 months after the basal measurements. There was a negative relationship between TSH levels and eGFR at baseline measurements, but TSH levels did not seem to predict future decline of eGFR levels. No relationship was observed between urine albumin/ g‧cre levels and thyroid function. CONCLUSION: Thyroid dysfunction and thyroid autoantibodies were not different in prevalence between patients with type 2 diabetes and controls, although in patients with type 2 diabetes, the fT3/fT4 ratio was decreased. Basal thyroid function did not predict future diabetes control or renal function within 24 months of follow-up.

Manganese and thyroid function in the national health and nutrition examination survey, 2011-2012.

CONTEXT: Manganese (Mn) exposure is prevalent, as it is found naturally as ionized trace elements and released into the environment as a byproduct of manufacturing and waste disposal. Animal and human studies have suggested variable effects on thyroid function, but the association of Mn exposure with thyroid function has not been evaluated in a national sample. OBJECTIVE: To investigate the associations between serum and urinary Mn levels and serum thyroid hormone concentrations in a nationally representative sample. DESIGN, SETTING, PARTICIPANTS, AND INTERVENTION: This was a cross-sectional analysis of data from the 2011-2012 National Health and Nutrition Examination Survey among 1360 participants. MAIN OUTCOME MEASURES: Serum thyroid stimulating hormone (TSH), total triiodothyronine (T3), total thyroxine (T4), free T3, and free T4. RESULTS: Serum Mn levels were positively associated with increasing total T4, free T3, and total T3 in the whole cohort (p < 0.01). Urinary Mn levels were not associated with thyroid hormone levels. When subgroup analyses were performed by gender, only males had total T4 associated with serum Mn [ß = 0.01, p < 0.01, confidence interval (CI): 0.004-0.018]. In individuals under 22 years old, serum Mn was significantly associated with total T4 (ß = 0.02, p = 0.002, CI: 0.008-0.029). Serum Mn was positively associated with Free T3 in both genders (ß = 0.07, p < 0.001). CONCLUSION: While our findings do not suggest clinical thyroid dysfunction, there is an association between serum Mn and subclinical changes in thyroid function that warrant further studies. Regulatory action should be considered as Mn-based organometallic compounds are being considered as replacements for lead in gasoline and may pose future risks to human health.

Relationship between caffeine intake and thyroid function: results from NHANES 2007-2012.

BACKGROUND: Moderate caffeine intake decreases the risk of metabolic disorders and all-cause mortality, and the mechanism may be related to its ergogenic actions. Thyroid hormones are vital in metabolic homeostasis; however, their association with caffeine intake has rarely been explored. OBJECTIVE: To investigate the association between caffeine intake and thyroid function. METHODS: We collected data on demographic background, medical conditions, dietary intake, and thyroid function from the National Health and Nutrition Examination Survey (NHANES) 2007-2012. Subgroups were classified using two-step cluster analysis, with sex, age, body mass index (BMI), hyperglycemia, hypertension, and cardio-cerebral vascular disease (CVD) being used for clustering. Restrictive cubic spline analysis was employed to investigate potential nonlinear correlations, and multivariable linear regression was used to evaluate the association between caffeine consumption and thyroid function. RESULTS: A total of 2,582 participants were included, and three subgroups with different metabolic features were clustered. In the most metabolically unhealthy group, with the oldest age, highest BMI, and more cases of hypertension, hyperglycemia, and CVD, there was a nonlinear relationship between caffeine intake and serum thyroid stimulating hormone (TSH) level. After adjusting for age, sex, race, drinking, smoking, medical conditions, and micronutrient and macronutrient intake, caffeine intake of less than 9.97 mg/d was positively associated with serum TSH (p = 0.035, standardized ß = 0.155); however, moderate caffeine consumption (9.97-264.97 mg/d) indicated a negative association (p = 0.001, standardized ß = - 0.152). CONCLUSIONS: Caffeine consumption had a nonlinear relationship with serum TSH in people with metabolic disorders, and moderate caffeine intake (9.97 ~ 264.97 mg/d) was positively associated with serum TSH.

Trimester-specific reference intervals for thyroid function parameters in pregnant Caucasian women using Roche platforms: a prospective study.

BACKGROUND: Standard thyroid function parameters reference intervals (RI) are unsuitable during pregnancy, potentially resulting in incongruous treatments that may cause adverse effects on pregnancy outcomes. We aimed at defining trimester-specific TSH, FT4 and FT3 RI, using samples longitudinally collected from healthy Caucasian women. MATERIALS AND METHODS: Blood samples from 150 healthy Caucasian women, who had a physiological gestation and a healthy newborn at term, were collected in each trimester and at around six months post-partum. They showed mild iodine deficiency. After excluding women with overt TSH abnormalities (> 10 mU/L) and/or TPO antibodies, data from 139 pregnant women were analyzed by means of widely used Roche platforms, and TSH, FT4 and FT3 trimester-specific RI were calculated. Post-partum data were available for 55 subjects. RESULTS: Serum TSH RI were 0.34-3.81 mU/L in the first trimester, and changed slightly to 0.68-4.07 U/L and 0.63-4.00 mU/L in the second and third trimester, respectively. Conversely, both FT4 and FT3 concentrations progressively decreased during pregnancy, the median values in the third trimester being 14.8% and 13.2% lower, respectively, than in the first trimester. Thyroid function parameters in the first trimester were similar to those measured after the end of pregnancy. CONCLUSIONS: This study calculates trimester-specific RI for thyroid function parameters in pregnancy, and proposes the reference limits that should be adopted when using Roche platforms in Caucasian women.

Iodine Intake Based on a Survey from a Cohort of Women at Their Third Trimester of Pregnancy from the Bosque County Chile.

Adequate iodine nutrition is fundamental for all humans and is critical during pregnancy and lactation due to iodine forms part of the structure of thyroid hormones (THs) and it is required for THs function. Iodine is a scarce micronutrient that must be obtained from the diet. Sufficient iodine can be found in the nature from seafood and given it is not frequently consumed by Chileans, public health policies state that table salt in Chile must be iodized. Health plans must be monitored to determine if the intake of iodine is being appropriated and the population has not fallen in deficiency or excess. The aim of this work was to evaluate iodine intake in 26 women at the third trimester of pregnancy. Pregnant women are resident from El Bosque a low-income County located in Santiago de Chile. These Chilean pregnant women were recruited by nutritionist at the Centros de Salud familiar (CESFAM). A 24 h dietary recall (24 h-DR) was applied to them to evaluate iodine intake. Samples of urine and blood were taken by health professionals to analyze parameters of thyroid function and to measure urine iodine concentration (UIC). The survey analysis showed that the iodine consumption in these pregnant women derived mainly from salt, bread and milk and not from seafood. The survey analysis indicated that iodine intake was above the requirements for pregnant women. However, the average UIC indicated that iodine intake was adequate, suggesting the need to find a better parameter to determine iodine intake in pregnant women.

Changes in Secretion of the Thyroid and Pituitary Glands with a Gradual Decrease in Deuterium Body Content.

We studied changes in the secretion of thyroid hormones and pituitary thyroid-stimulating hormone (TSH) in young mature male Wistar rats during gradual decrease in deuterium body content. The rats received deuterium-depleted water ([D]=10 ppm) instead of tap water for 21 days. As soon as after 1 day, an increase in the secretion of thyroid hormones was recorded. On day 14, secondary hypothyroidism due to a sharp decrease in TSH secretion by the pituitary gland was found. By day 21, secretion of the thyroid hormones increased, and the reciprocal dependence between the concentrations of thyroid hormones and TSH was restored. Thus, the thyroid gland showed a higher sensitivity to a decrease in the deuterium content in the body than the hypothalamic-pituitary complex. The second difference was in type of response: activation of the secretory processes in the thyroid gland and a transient decrease in the secretory activity of pituitary gland thyrotropes to a decrease in deuterium content.

Nkx2-1 and FoxE regionalize glandular (mucus-producing) and thyroid-equivalent traits in the endostyle of the chordate Oikopleura dioica.

The endostyle is a ventral pharyngeal organ used for internal filter feeding of basal chordates and is considered homologous to the follicular thyroid of vertebrates. It contains mucus-producing (glandular) and thyroid-equivalent regions organized along the dorsoventral (DV) axis. Although thyroid-related genes (Nkx2-1, FoxE, and thyroid peroxidase (TPO)) are known to be expressed in the endostyle, their roles in establishing regionalization within the organ have not been demonstrated. We report that Nkx2-1 and FoxE are essential for establishing DV axial identity in the endostyle of Oikopleura dioica. Genome and expression analyses showed von Willebrand factor-like (vWFL) and TPO/dual oxidase (Duox)/Nkx2-1/FoxE as orthologs of glandular and thyroid-related genes, respectively. Knockdown experiments showed that Nkx2-1 is necessary for the expression of glandular and thyroid-related genes, whereas FoxE is necessary only for thyroid-related genes. Moreover, Nkx2-1 expression is necessary for FoxE expression in larvae during organogenesis. The results demonstrate the essential roles of Nkx2-1 and FoxE in establishing regionalization in the endostyle, including (1) the Nkx2-1-dependent glandular region, and (2) the Nkx2-1/FoxE-dependent thyroid-equivalent region. DV axial regionalization may be responsible for organizing glandular and thyroid-equivalent traits of the pharynx along the DV axis.

Physiological and metabolic adaptations in pregnancy: importance of trimester-specific reference intervals to investigate maternal health and complications.

Diagnosis, prognostication, and monitoring of maternal health throughout pregnancy relies on laboratory testing, including but not limited to key markers of thyroid, hepatic, cardiac, hematology, and renal function. Dynamic physiological processes during gestation significantly influence the maternal biochemistry that supports both the mother and fetus. Resultant changes in blood biochemistry alter the expected values of common laboratory tests. However, the importance of pregnancy-specific reference intervals for laboratory test result interpretation and appropriate monitoring of maternal health and complications is underappreciated. Most clinical laboratories continue to use non-pregnant adult reference intervals for laboratory test interpretation in pregnancy. The current review summarizes and critically evaluates the available literature regarding physiological and metabolic adaptations in pregnancy and their influence on common biomarkers of health and disease. The main laboratory parameters discussed include thyroid, hepatic, metabolic, renal, hematology, inflammatory, and cardiac markers. Considering the available data, further studies are urgently needed to establish trimester-specific reference intervals in healthy pregnant women on updated analytical platforms. Without such data, the standard of clinical laboratory service in pregnancy remains compromised and affects the quality of maternal-fetal healthcare.