Normal Thyroid-stimulating Hormone Levels Research Articles

CONGENITAL HYPOTHYROIDISM IN NEWBORN AND ASSOCIATION WITH SOCIODEMOGRAPHIC PARAMETERS AMONG NEONATE DELIVERED AT MILITARY HOSPITAL IN A CITY OF CENTRAL INDIA

Objectives: The present study aims to assess the incidence of congenital hypothyroidism (CH) among neonates in a tertiary care hospital in central India, examining its association with various sociodemographic parameters. Methods: This cross-sectional study, conducted between January and December 2022, included all live births at a tertiary care center in Jabalpur, Madhya Pradesh. Cord blood thyroid-stimulating hormone (TSH) levels were measured for all newborns as part of routine screening. Sociodemographic data, including maternal age, gestational age, birth order, and newborn sex, were collected. Universal sampling was employed, encompassing all consenting parents and their neonates. Results: Among 388 live births, TSH values ranged from 0.23 to 35.59 mIU/L, with a mean TSH of 8.76±5.92 mIU/L. Of the neonates, 95.9% had normal TSH levels, while 4.1% exhibited elevated levels. Subsequent follow-up identified CH in two neonates (5.2 per thousand live births). Analysis revealed no significant association between elevated TSH levels and maternal age or newborn sex. However, a significant association was observed with gestational age. Birth order also displayed significance, with the third birth order having a higher proportion of neonates with raised TSH levels. Conclusion: This study highlights the importance of CH screening in preventing long-term complications and the various sociodemographic factors linked to CH, such as maternal age, gestational age, and birth order.

The Relationship Between TSH and Indirect Bilirubin Levels in Neonates Suspected of Having Jaundice

Background: Congenital hypothyroidism (CH) is a condition of thyroid hormone deficiency that occurs at birth. The TSH (thyroid-stimulating hormone) test is crucial for diagnosing hypothyroidism. CH is known to cause prolonged unconjugated hyperbilirubinemia. Therefore, this study aimed to analyze the relationship between TSH and indirect bilirubin levels in neonates suspected of having jaundice. Methods: This is a non-experimental, retrospective study conducted at Lombok Dua Dua Lontar Mother and Child Hospital in Surabaya. The study involved data collection on neonates aged 2–7 days suspected of jaundice, whose TSH and indirect bilirubin levels were measured between November 2022 to April 2024. Results: Among 100 neonates, 62% were aged 2-4 days, while 38% were aged 5-7 days. The majority were male (56%), with female comprising 44%. Of the 100 neonates, only 1 (1%) had borderline TSH levels, while 99% had normal TSH levels. Hyperbilirubinemia was observed in 94% of the neonates, while 6% had normal indirect bilirubin levels. Statistical analysis using the Spearman correlation showed no significant link between TSH and indirect bilirubin levels (p = 0.802). Conclusions: While this study did not find a clear connection between TSH and indirect bilirubin levels in neonates suspected of having jaundice, one case of borderline TSH was identified. This neonate required referral to pediatric endocrinology, as untreated congenital hypothyroidism can lead to mental retardation. Despite limited research linking TSH and bilirubin levels in jaundiced neonates, routine screening for congenital hypothyroidism using TSH testing should be reconsidered. Future studies could benefit from focusing on specific causes of neonatal jaundice to help narrow down research questions in this area.

Estimating the Prevalence of Primary Hypothyroidism in Karbala City, and Modulation of Clinical Manifestations Among Patients Receiving Levothyroxine; A Single Center Study

Background: Hypothyroidism has a wide range of clinical manifestations and general symptoms, including but not limited to obesity, tiredness, poor concentration, depression, widespread muscle soreness, menstruation abnormalities, and constipation. The administration of a daily dosage of levothyroxine is sufficient for the successful management of hypothyroidism, as it facilitates the restoration of serum thyroid stimulating hormone (TSH) levels to their normal range. Several factors can influence the absorption of levothyroxine in the human body, including age, weight, the presence of other medical problems, and dietary intake. The aim of this study was to assess the prevalence of primary hypothyroidism and alteration in clinical presentation associated with replacement therapy. Methods: This was a cross-sectional, observational study conducted over at Al Hassan Metabolism, Endocrine, and Diabetes Center (HMEDC) in Karbala city. The study team created a questionnaire, and data was collected from face-to-face patient interviews, which included various sociodemographic variables, TSH and ferritin levels, drug interactions, as well as signs and symptoms exhibited both prior to and following treatment. Additionally, the patient treatment regimen and the specific doses of levothyroxine administered are also recorded. Results: the total number of cases visited Al Hassan Metabolism, Endocrine, and Diabetes Center (HMEDC) during the study period was (10800). The prevalence of thyroid diseases was 300 (2.8%). The rate of primary hypothyroidism out of the total number of hypothyroid cases was 85.1%. (61%) of the patients had normal levels of TSH whereas (42%) of the patients were found to be undertreatment. A total of (84%) of the patients exhibited normal levels of ferritin. The patients exhibited a reduction in their signs and symptoms following the administration of therapy. Conclusion: treatment with levothyroxine improved sluggish speech, constipation, lack of appetite, cold sensitivity, weight gain, and weariness. There is no observed correlation between the dosage of levothyroxine and the manifestation of signs and symptoms.

Associative Learning in Subclinical Hypothyroidism at Different Ranges of Thyroid Stimulating Hormone: A Cambridge Neuropsychological Test Automated Battery (CANTAB) Study of Visual Paired Association Learning Task.

Associative learning deficits are constantly found in subclinical hypothyroidism (SCH). Despite achieving normal thyroid stimulating hormone (TSH) levels, a considerable number of patients undergoing levothyroxine (LT-4) treatment frequently complain about memory retrieval. The Paired Association Learning (PAL) task involves computerised testing on the CANTAB- Cambridge Neuropsychological Test Automated Battery, also considered a screening tool for Alzheimer's disease (AD). This study aimed to investigate the impact of different levels of TSH on visual associative learning in SCH and determine if these impairments were reversed with LT-4. A total of 134 participants were included in this cross-sectional study. Group 1: 35 healthy controls; patients with SCH (Group 2: 33 newly identified cases; Group 3: 32 patients on LT-4 with elevated TSH; Group 4: 34 euthyroid but on LT-4). A thyroid profile and a neuropsychological clinical assessment were done. The visual PAL task was performed on CANTAB. PAL was significantly impaired (p = <0.05) in all 3 patient groups as compared to Group 1. The PAL total errors (adjusted) scores were significantly higher in Groups 2 and 3, indicating that associative learning is definitely impaired in SCH, reaching levels previously seen in patients with AD. Our findings encourage screening for visual associative learning or memory retrieval in patients with SCH. The study present has established a more reasonable threshold of TSH 2.5mIU/L to encourage examination of associative learning and the initiation of LT-4 in SCH. Poor PAL task performance in patients with SCH may have significant implications in clinical settings for suspecting AD.

The Association Between Hypothyroidism and Cognitive Function Change in Women across the Menopause Transition: The Study of Women's Health Across the Nation.

Background: Patients treated for hypothyroidism with levothyroxine (LT4) monotherapy may present with persistent hypothyroidism symptoms, including cognitive symptoms, despite having a normal thyroid stimulating hormone (TSH) level. It remains unclear whether LT4 monotherapy is sufficient to normalize cognitive function outcomes over time. Methods: This is a multisite longitudinal study of a diverse group of women during midlife representing 5 ethnic/racial groups from 7 enrollment sites across the United States in the Study of Women's Health Across the Nation. Women were screened for a history of thyroid disease and the use of LT4. The study consisted of two primary groups: women with LT4-treated hypothyroidism and control women without thyroid disease. Each participant completed up to 9 cognitive assessments over the study period testing processing speed, working memory, and episodic memory (immediate and delayed recall). Multivariable generalized linear mixed models of scores for each cognitive assessment were developed to determine the association between LT4-treated hypothyroidism and cognitive function trajectories. Covariates included sociodemographic, clinical characteristics, and menopausal status (pre/early peri, late peri, and surgical/post). Sensitivity analyses were conducted to assess the impact of abnormal TSH levels and practice effects (i.e., improvements in scoring after repeated testing). Results: Of the 2033 women who were included in the study, 227 (11.2%) met criteria for LT4-treated hypothyroidism. At baseline, both processing speed and working memory scores were higher in LT4-treated women (mean processing speed scores: 56.5 vs 54.4; p value = 0.006; mean working memory scores: 6.8 vs 6.4; p value = 0.018). However, when considering the effect of LT4-treated hypothyroidism over time, there were no significant differences in the rate of cognitive decline (in any measure) between the hypothyroidism and control groups with or without covariate adjustment. The results were similar when considering LT4-treated women with abnormal TSH levels or after minimizing practice effects. Conclusions: We observed no difference in cognitive decline between women with LT4-treated hypothyroidism and women without thyroid disease. For similar aged patients with cognitive complaints, if thyroid function testing is normal, clinicians should consider causes other than inadequate thyroid hormone treatment to explain these symptoms.

A confusing situation in the clinic: isolated maternal hypothyroxinemia

Isolated maternal hypothyroxinemia (IMH) is a common problem in the clinic. There is a normal maternal thyroid stimulating hormone (TSH) level with a low maternal free thyroxine (FT4) level. The aim of this review is to explain IMD in the light of current literature and to contribute to clinicians in the management of IMH. Iodine deficiency is the most important factor in etiology. The effects of IMH on the pregnant woman and the fetus are not clear. However, it is a serious concern among serious clinicians, especially considering the importance of the effect of thyroid hormones on fetal brain development. As for the treatment of IMH, the number of studies conducted is not sufficient and there is no consensus and evidence on levothyroxine treatment. However, there is a consensus on iodine supplementation and it is recommended to take 250 mg of iodine daily. As a result, IMH is a problem that should be taken seriously during pregnancy and care should be taken regarding its diagnosis and treatment. Additionally, more research is needed on the effects and treatment of IMH on pregnant and fetal health

Analysis of Inflammatory and Thyroid Hormone Levels Based on Hepatitis A and B Virus Immunity Status: Age and Sex Stratification.

This study investigated the potential associations between hepatitis virus antibody status and thyroid and inflammatory function. The C-reactive protein (CRP), thyroid-stimulating hormone (TSH), and free thyroxine (FT4) levels were measured in individuals with and without antibodies to the hepatitis A virus (HAV) and hepatitis B virus (HBV). Participants were stratified by age, sex, and HAV/HBV antibody status. Participants with and without antibodies to HAV and HBV had normal CRP, TSH, and FT4 levels. However, notable discrepancies were observed in FT4 levels among participants with HAV antibodies and in CRP and FT4 levels among those with both HAV and HBV antibodies, suggesting potential associations between viral immunity and thyroid function, especially in younger participants. Significant variations in thyroid hormone levels were noted when the sample was stratified by sex and HAV and HBV antibody status, indicating that the association between antibody status and thyroid hormone levels varied by sex. This study underscores the need for further research on the effect of viral immunity on inflammatory parameters and thyroid hormone levels.

Association Between Particulate Matter Exposure and Preterm Birth in Women With Abnormal Preconception Thyrotropin Levels: Large Cohort Study.

Prior research has linked exposure to particulate matter with an aerodynamic diameter of ≤2.5 μm (PM2.5) with preterm birth (PTB). However, the modulating effect of preconception thyroid stimulating hormone (TSH) levels on the relationship between PM2.5 exposure and PTB has not been investigated. This study aimed to assess whether preconception TSH levels modulate the impact of PM2.5 exposure on PTB. This cohort study was conducted in Guangdong, China, as a part of the National Free Pre-Pregnancy Checkups Project. PM2.5 exposure was estimated by using the inverse distance weighting method. To investigate the moderating effects of TSH levels on trimester-specific PM2.5 exposure and PTB, we used the Cox proportional hazards model. Additionally, to identify the susceptible exposure windows for weekly specific PM2.5 exposure and PTB, we built distributed lag models incorporating Cox proportional hazards models. A total of 633,516 women who delivered between January 1, 2014, to December 31, 2019, were included. In total, 34,081 (5.4%) of them had abnormal preconception TSH levels. During the entire pregnancy, each 10-μg/m3 increase in PM2.5 was linked to elevated risks of PTB (hazard ratio [HR] 1.559, 95% CI 1.390-1.748), early PTB (HR 1.559, 95% CI 1.227-1.980), and late PTB (HR 1.571, 95% CI 1.379-1.791) among women with abnormal TSH levels. For women with normal preconception TSH levels, PM2.5 exposure during the entire pregnancy was positively associated with the risk of PTB (HR 1.345, 95% CI 1.307-1.385), early PTB (HR 1.203, 95% CI 1.126-1.285), and late PTB (HR 1.386, 95% CI 1.342-1432). The critical susceptible exposure windows were the 3rd-13th and 28th-35th gestational weeks for women with abnormal preconception TSH levels, compared to the 1st-13th and 21st-35th gestational weeks for those with normal preconception TSH levels. PM2.5 exposure was linked with a higher PTB risk, particularly in women with abnormal preconception TSH levels. PM2.5 exposure appears to have a greater effect on pregnant women who are in the early or late stages of pregnancy.

A Critical Investigation of Sick Euthyroid Syndrome in Chronic Heart Failure Patients: Addressing the Need for Accurate Thyroid Assessment.

Background The body undergoes numerous metabolic changes during severe illness or physiological stress to protect itself by lowering metabolism and reducing overall demands. This evolutionary adaptation dates back to early human development, long before the advent of ICU facilities and advanced treatments. One such protective mechanism is Sick Euthyroid Syndrome (SES), also known as Non-thyroidal Illness Syndrome (NTIS). SES commonly occurs in critically ill patients and is frequently observed in conditions such as heart failure, chronic kidney disease, and severe sepsis. This syndrome is characterized by abnormal thyroid function tests in patients with acute or chronic systemic illnesses who do not have intrinsic thyroid disease. Typically, these patients exhibit low serum levels of triiodothyronine (T3), normal or low levels of thyroxine (T4), and normal or low thyroid-stimulating hormone (TSH) levels. SES is believed to be an adaptive response to illness, aimed at reducing the body's metabolic rate and conserving energy during severe physiological stress. This original article delves into SES's prevalence and clinical impact in these settings. Materials and methods The study aims to determine the prevalence of SES in patients with long-standing heart failure, elucidate the relationship between thyroid function and heart failure severity, and assess its impact on various hematological and clinical parameters. This observational, cross-sectional study was conducted at Dr. D. Y. Patil Medical College, Hospital and Research Centre, Pune, India, a 2011-bed hospital, over one and a half years. This study included 70 patients with chronic heart failure, aged 18 years and above, defined by a left ventricular ejection fraction of 40% or less and a Boston criteria score of 8 or more. Patients were excluded if they had a history of thyroid dysfunction, clinical sepsis, or were taking thyroid-affecting drugs. Results The study provides important insights into the prevalence and impact of SES in long-standing heart failure patients. It found that a significant 44.29% of these patients exhibited low T3 levels, highlighting the substantial occurrence of SES in this population. Additionally, the study revealed a negative correlation between N-terminal pro-b-type natriuretic peptide (NT-proBNP) levels, Boston score, and total T3, suggesting that as indicators of heart failure severity worsen, total T3 levels may decrease further. Another key finding is the high prevalence of anemia among heart failure patients, with a notable gender disparity: 92.11% of male patients were affected compared to 50% of female patients. Conclusion The study concluded that SES is significantly prevalent among long-standing heart failure patients, further indicating that thyroid suppression increases with the severity of heart failure. Recognizing SES can guide tailored treatments, prompting intensive monitoring and optimized heart failure management.Additionally, the study found a high prevalence of anemia, particularly among male patients, highlighting the need for gender-specific considerations in managing heart failure. These findings underscore the importance of routine thyroid function assessments and regular monitoring of anemia in heart failure patients. Future research should focus on improving clinical outcomes through comprehensive management of both thyroid function and anemia in these patients.

The role of non-invasive oscillometric method to detect aortic stiffness in patients with subclinical hypothyroidism

Introduction Subclinical hypothyroidism (SCH) is a biochemical condition that is diagnosed when peripheral free thyroid hormone levels are within normal reference laboratory range but serum thyroid-stimulating hormone (TSH) levels are mildly elevated. The aim of this study was to investigate the relationship between SCH and arterial stiffness using two different non-invasive methods, including echocardiography and oscillometric arteriography. Material and Methods The study included 33 newly diagnosed SCH patients and 34 age- and gender-matched healthy controls. Systolic and diastolic diameters and elastic parameters of the aorta were calculated by 2D Transthoracic echocardiography (TTE). Central blood pressure and aortic stiffness values of patient groups were measured noninvasively from the brachial artery using Mobil-O-Graph arteriography. Pulse wave velocity (PWV) and augmentation index (AIx) were used as arterial stiffness indicators. Results There was no significant difference between SCH and control groups with regard to age, gender, and body mass index (BMI). Aortic strain and aortic distensibility, were significantly lower in the SCH group than in the control group (p < 0.001). PWV and AIx which measured by Mobil-O-Graph arteriography were found to be significantly higher in the subclinical hypothyroid group compared to the control group (p < 0.05). Conclusion Aortic stiffness assessed by TTE and Mobil-O-Graph arteriography deteriorated in patients with SCH after excluding other cardiovascular risk factors. The assessment of aortic stiffness by the oscillometric method was easy and useful for widespread clinical use.

O-304 Is there any association between thyroid-stimulating hormone (TSH) levels and semen parameters? A retrospective study in a European fertility clinic

Abstract Study question Is there any association between TSH levels and semen parameters considering age, body mass index (BMI), and life style? Summary answer In line with the results of logistic regression, normal TSH values increase the probability of having a higher sperm count. What is known already To date, association between TSH levels, semen parameters and other hormones have not been thoroughly investigated in European andrology labs. However, while andrology guidelines do not support a systematic evaluation of thyroid function, some studies reported that men in infertility clinics have higher risks of presenting thyroid disorders than in the general population. Study design, size, duration Both partners investigated for sterility are routinely checked for TSH in the work up of our clinic. We examined for 2021 – 2023 all 347 male patients (infertile/fertile) with complete records of demographic data, semen analysis and hormone analysis. Patients suffering from azoospermia, genital tract infections, hormonal supplementation or heavy medical treatments (radiotherapy, chemotherapy), as well as those receiving iodine supplements or drugs that could potentially affect testicular or thyroid physiology, were excluded. Participants/materials, setting, methods Age, BMI, smoking and detailed alcohol intake were recorded. A blood sample was taken from each patient in connection with the sperm collection to measure TSH, FSH, LH, prolactin and testosterone levels. Spearman’s correlation coefficients were used to determine correlations among hormones. Statistical analyses were performed using semen parameters as dichotomized using WHO reference values. Men above the reference values for count, concentration and motility were used as comparison subjects in multivariate logistic regression. Main results and the role of chance The analysis explored relationships between age, BMI, smoking, alcohol consumption and semen parameters with TSH hormone levels. The mean age of the participants was 35.8 ±7.43 years and BMI was 27.2 ±4.54 kgm-2. Of all participants, 37% reported being smokers, alcohol consumption was 3% regularly, 35% occasionally, 44% rarely, 18% none. Considering a TSH level (0.4-4 mIU/l) as normal, the prevalence of thyroid dysfunction in the cohort was 0.9% (TSH &amp;lt;0.4) and 1.1% (TSH &amp;gt;4) implying that most patients had normal TSH levels. In this cohort, TSH levels were not found to be significantly affected by age, BMI, smoking or alcohol consumption despite being known as putative confounding factors influencing TSH levels. Among the various hormones evaluated, only one significant positive correlation was found between TSH and Prolactin (r = 0.199, p = 0.0001), while a trend towards a negative correlation between TSH and LH (r=-0.101, p = 0.073) was suggested. Multivariate logistic regression analysis showed, not surprisingly, that age was a factor influencing sperm count, sperm concentration as well as total and progressive sperm motility. Logistic regression also showed that when TSH values were within the normal range, sperm counts were significantly higher (OR:1.302, P = 0.043; CI95%:1.009-1.681). Limitations, reasons for caution Sperm morphology and viability were not recorded. Evaluation of thyroxine (T4) and triiodothyronine (T3) levels could be useful. The crucial role of iodine and the complex relationship between iodine and selenium status (which depends on geographical location) in affecting thyroid function should be taken into account in future studies. Wider implications of the findings Male patients with abnormal TSH levels are not very common in this region. Normal TSH level is associated with a higher sperm count. TSH assessment in infertile couples should be routine in both partners, given the recorded worldwide increase in thyroid dysfunction and iodine deficiency. Trial registration number not applicable

The association of higher thyroid stimulating hormone levels in the normal range with unexplained infertility: A cross-sectional study.

Since thyroid hormones have an essential role in energy production, early development of the human placenta, embryo development, and implantation, abnormalities in thyroid function can significantly affect pregnancy outcomes. The present study aimed to investigate the effect of higher thyroid-stimulating hormone (TSH) levels in the normal range in euthyroid women with unexplained infertility. In this cross-sectional study, we evaluated the data for 300 euthyroid women aged between 18 and 39 yr with normal TSH levels ( 5 mIU/L) referred to Yazd Reproductive Sciences Institute, Yazd, Iran from December 2018-March 2021 in 2 groups: the case group (with unexplained infertility) and the control group (with male factor infertility). Finally, age, body mass index, and serum levels of TSH were extracted from participants' medical records and compared between groups. The mean age and TSH level of participants were 31.52 3.52 yr and 1.24 2.59 mIU/L, respectively. 142 women (47.3%) had TSH 2.5, and 158 women (52.7%) had TSH 2.5 mIU/L. The women with unexplained infertility had significantly higher TSH levels than controls in the same normal range (0.62 vs. 0.64 mIU/L, p 0.001). Although a more significant proportion of women in the case group had TSH levels 2.5 mIU/L, we did not find a significant association between TSH levels and age or body mass index. Women with unexplained infertility have a higher level of serum TSH in the normal range ( 2.5 mIU/L) than the control group. So, the effect of TSH treatment on these women should be considered.

Effects of statin use on serum creatinine phosphokinase levels in normal thyroid function.

Statins are common lipid-lowering agents used in dyslipidemia. However, they increase serum creatinine phosphokinase (CPK) levels. Currently, there are no studies on the effect of thyroid-stimulating hormone (TSH) levels on CPK levels after statin administration. Therefore, this study aimed to investigate CPK level alterations after statin administration according to TSH quartiles in participants with euthyroidism. This retrospective analysis included 25,047 patients with euthyroidism. CPK levels were measured before and 6 months after statin administration. Normal TSH levels were divided into four quartiles, and the CPK levels and proportions of patients with normal CPK levels after statin administration for each TSH quartile were evaluated. The baseline CPK level was significantly higher in the lowest TSH quartile (Q1) compared to the other quartiles but decreased after statin administration. Thus, the difference between the CPK levels and the other quartile groups was not significant. The proportion of patients with normal CPK levels was also significantly lowest in Q1 before statin administration; however, no significant difference was noted in the ratio among each group after statin administration. These findings were consistent with the findings of the analysis according to statin intensity. In patients in the lowest TSH quartile of the normal TSH range, the CPK level decreased, and the proportion of normal CPK levels increased significantly after statin administration. However, similar changes were not observed in other TSH quartiles. Therefore, further studies are required to mechanistically confirm these conclusions.

Resistance To Thyroid Hormone Receptor Alpha Due to Heterozygous Pathogenic Variant in THRA Gene: A Case Report from India

Background: Thyroid Hormone Receptor Alpha (THRA) gene mutation is a thyroid hormone resistance syndrome characterized by non-responsiveness of target tissues to the active form of TH (T3). Clinical Description: We describe a heterozygous missense variant in exon 8 of THRA gene detected in a 2-month-old female with clinical phenotype of hypothyroidism, low free thyroxine, elevated free triiodothyronine &amp; normal levels of thyroid stimulating hormone. Management &amp; Outcome: Clinical improvement in linear growth, motor development domain, hypotonia &amp; constipation were noted with levothyroxine therapy but insufficiencies in cognitive and fine motor skills may remain. Conclusion: THRA gene mutation should be considered in patients with features of clinical hypothyroidism and elevated free T3, decreased/ normal free thyroxine &amp; normal thyroid-stimulating hormone levels.

Triiodothyronine/Thyroxine Ratio as a Marker of Clinical Response to Levothyroxine Replacement in Patients With Hypothyroidism.

Hypothyroidism is one of the most common endocrine disorders with a simple therapy, that is levothyroxine (LT4). A normal thyroid-stimulating hormone (TSH) measurement is used as a marker of optimal replacement. But, many patients still have symptoms. Triiodothyronine (T3), thyroxine (T4), and their ratio may correlate with clinical improvement. The study aims to assess the T3/T4 ratio as a marker of clinical response in patients with hypothyroidism. Method:A cross-sectional study was conducted from June to November 2022 at Faiha Specialized Diabetes, Endocrine, and Metabolism Center, in Basrah, southern Iraq. We included 48 adult patients with primary hypothyroidism on LT4 treatment only and TSH within the target reference range for at least within the last six months. Each patient was subjected to a questionnaire that was designed to capture hypothyroidism-related complaints in the form of a five-point Likert scale. Biochemical assessments were done with the measurement of TSH, T3, and T4. Despite having a normal TSH level, nearly all the patients had persistent and varying severity of clinical complaints of hypothyroidism. Tiredness, hair problems, weight gain, and cold intolerance were the most severely persistent symptoms. Patients with scores of two and more for weight gain, cold intolerance, and skin problems had significantly lower T3/T4 ratios (P = 0.04, 0.002, and 0.02, respectively), while in the remaining clinical symptoms, the T3/T4 ratio did not differ significantly. A low T3/T4 ratio was significantly associated with resistant symptoms of hypothyroidism and may be used as a marker for treatment efficacy with TSH rather than TSH value alone.

Thyroid Hormone Homeostasis in Levothyroxine-treated Patients: Findings From ELSA-Brasil.

The effectiveness of levothyroxine (LT4) in restoring thyroid hormone (TH) homeostasis, particularly serum thyroxine (T4) and triiodothyronine (T3) levels, remains debatable. This work aimed to assess TH homeostasis in LT4-treated individuals using data from the Longitudinal Study of Adult Health in Brazil (ELSA-Brasil) study. The ELSA-Brasil study follows 15 105 adult Brazilians (aged 35-74 years) over 8.2 years (2008-2019) with 3 observation points assessing health parameters including serum thyrotropin (TSH), free T4 (FT4), and free T3 (FT3) levels. We analyzed 186 participants that initiated treatment with LT4 during the study, and 243 individuals continuously treated with LT4 therapy. Initiation of therapy with LT4 resulted in an 11% to 19% decrease in TSH, an approximately 19% increase in FT4, and a 7% reduction in FT3 serum levels (FT3 dropped >10% in ∼40% of the LT4-treated patients). This was associated with an increase in triglyceride levels and utilization of hypolipidemic and antidiabetic medications. Participants continuously treated with LT4 exhibited a stable elevation in serum FT4 and a reduction in serum FT3 and TSH levels. While 115 participants (47.3%) had at least 1 serum FT4 levels above the control reference range (>1.52 ng/dL), 38 participants (15.6%) had at least 1 serum FT3 below the reference range (<0.23 ng/dL). The present results challenge the dogma that treatment with LT4 for hypothyroidism restores TH homeostasis in all patients. A substantial number of LT4-treated patients exhibit repeated FT4 and FT3 levels outside the normal reference range, despite normal TSH levels. Further studies are needed to define the clinical implications of these findings.

Overt hypothyroidism in pregnancy and language development in offspring: is there an association?

PurposeOvert hypothyroidism during pregnancy is linked to various obstetric complications, such as premature birth and fetal death. While some studies have shown that maternal hypothyroidism can impact a child's Intelligence Quotient (IQ) and language development, findings are controversial. The aim of this study was to explore the connection between treated maternal hypothyroidism during pregnancy and offspring neurodevelopment, focusing on learning and language and examining related maternal obstetric complications.MethodsGroup 1 included 31 hypothyroid women with elevated thyroid stimulating hormone (TSH) (> 10 mU/L, > 10 µIU/mL) during pregnancy, and Group 2 had 21 euthyroid women with normal TSH levels (0.5–2.5 mU/L, 0.5–2.5 µIU/mL). Children underwent neuropsycological assessments using the Griffiths-II scale.ResultsPregnancy outcome showed an average gestational age at delivery of 38.2 weeks for hypothyroid women, compared to 40 weeks for controls, and average birth weight of 2855.6 g versus 3285 g for controls, with hypothyroid women having children with higher intrauterine growth restriction (IUGR) prevalence and more caesarean sections. The 1-min APGAR score was lower for the hypothyroid group's children, at 8.85 versus 9.52. Neuropsychological outcomes showed children of hypothyroid mothers scored lower in neurocognitive development, particularly in the learning and language subscale (subscale C), with a notable correlation between higher maternal TSH levels and lower subscale scores.ConclusionFetuses born to hypothyroid mothers appeared to be at higher risk of IUGR and reduced APGAR score at birth. Neurocognitive development seemed to affect language performance more than the developmental quotient. This alteration appeared to correlate with the severity of hypothyroidism and its duration.

Association of pro-atherogenic risk factors with thyroid-stimulating hormone level in women 25–44 years old

Thyroid hormones play an important role in regulating metabolism. A large body of literature suggests an increased risk of developing metabolic syndrome (MS) in individuals with hypothyroidism, but little data exists on the effects of high-normal levels of thyroid-stimulating hormone (TSH) on metabolism.Material and methods. The study was conducted on a representative sample of people aged 25–44 years (n = 1513, of which 840 were women). The analysis included the results of 343 women. A questionnaire, anthropometric and biochemical study were carried out. Biochemical parameters were analyzed in quartiles of TSH content. Determination of MS was carried out using the criteria of NCEP ATP III (2001), IDF (2005), VNOK (2009).Results. TSH content in the examined sample was 1.5 [1.0; 2.2] mU/l (median [lower quartile; upper quartile]). Among women 25–44 years old, women with highly normal TSH level (3.1 [2.7, 3.8] mU/l) have less favorable metabolic parameters. MS was detected in 31 % cases, with a predominant increase in the frequency of abdominal obesity – in 51 %, with increased triglyceride levels in 18 %. Women with hypertriglyceridemia had higher TSH content than those with normal triglyceride levels (2.4 ± 1.6 vs. 1.8 ± 1.3 mU/L, respectively, p = 0.007).Conclusions. In women 25–44 years of age, high-normal TSH content is more often associated with metabolic unhealth.

Evaluating the progression to abnormal thyrotropin in euthyroid preconception women: a population-based study

Background Abnormal preconception thyrotropin levels were associated with fecundability and adverse fetomaternal outcomes, however, little is known regarding the natural change of serum thyrotropin in euthyroid preconception women. Thus, we performed a population-based study to evaluate the progression to abnormal thyrotropin in euthyroid preconception women.Methods This retrospective cohort study used data from the National Free Prepregnancy Checkups Project (NFPCP) collected between 2010 and 2020. Female Han Chinese participants aged 20–49 years who had two repeated NFPCP participations with a time interval of 1.5–3.0 years, confirmed non-pregnant status within this duration, and normal thyrotropin levels during their first participation were included for the analysis of thyrotropin abnormalities during the second NFPCP examination. Data were analyzed between June 1 and October 1, 2023.ResultsThis study included 186,095 euthyroid women of reproductive age (mean ± SD, 26.72 ± 4.70 years) whose preconception thyrotropin levels were between 0.37 and 4.87 mIU/L. The median follow-up time was 2.13 (IQR, 1.85–2.54) years. A total of 8,497 (4.57%) women developed abnormal thyrotropin, including 4,118 (2.21%) subnormal thyrotropin and 4,379 (2.35%) supranormal thyrotropin. Compared with the reference group (thyrotropin 1.01–2.00 mIU/L), the lower baseline thyrotropin group had greater risk of developing subnormal thyrotropin, and the higher baseline thyrotropin group had greater risk of developing supranormal thyrotropin. Moreover, the restricted cubic spline analysis revealed a U-shaped dose–response association of baseline thyrotropin levels or thyrotropin multiples of the median (MOM) levels against risk of subnormal thyrotropin in the follow-up, and a J-shaped dose–response association against risk of supranormal thyrotropin levels in the follow-up. We further found that baseline thyrotropin outside of 1.43–1.93 mIU/L or baseline thyrotropin MOM outside 0.59–1.36 would hava a higher risk of developing of abnormal thyrotropin.ConclusionsBoth low and high baseline thyrotropin were associated with a significantly increased risk of developing abnormal thyrotropin outcomes. The optimal preconception baseline thyrotropin levels may be between 1.43 mIU/L and 1.93 mIU/L or baseline thyrotropin MoM between 0.59 and 1.36 to minimize progression toward abnormal thyrotropin after 1.5–3.0 years. These findings may help with counseling of preconception thyroid function monitoring.

Three candidate SNPs show associations with thyroid-stimulating hormone in euthyroid subjects: Tehran thyroid study.

Previous studies have shown interindividual variation in free thyroxine (FT4) serum levels and thyroid stimulating hormone (TSH) in healthy persons. Genetic factors mainly determine this variation, and genome-wide association studies have increased the number of thyroid function-associated variants. The present study investigates the association of candidate variants with FT4 and TSH in a euthyroid Iranian population. A total of 2931 unrelated euthyroid subjects (FT4 10.29-21.88pmol/L; TSH 0.32-10 mIU/L, thyroid peroxidase antibody TPOAb < 33IU/mL in men and < 35IU/mL in women), with available genotypes were chosen from the Tehran Thyroid Study (TTS), to examine the impact of selected SNPs on thyroid hormone under the additive genetic model. In order to evaluate regional associations with FT4 and TSH levels, a haplotype analysis was done. We identified a strong association between the rs4338740-C allele and TSH in the adjusted model (β = -0.095, P-value = 0.0004). Also, findings indicated that rs4954192 ACMSD and rs4445669 CADM1 correlated with normal TSH levels (P-value = 0.011, P-value = 0.014, respectively). Haplotype analysis revealed that two haplotypes were significantly associated with TSH levels in euthyroid individuals. The ACGA and AC haplotypes on chromosomes 8 and 14 were significantly correlated with normal TSH levels, respectively (P-value = 0.014, P-value = 0.016). This is the first genetic association study with TSH and FT4 reference values in an Iranian population. Our findings indicate that a few gene variants associated with the reference values of TSH in other populations are also associated with the reference values of TSH in Iranians. The online version contains supplementary material available at 10.1007/s40200-023-01383-2.