Cardiovascular risk and subclinical hypothyroidism: focus on lipids and new emerging risk factors. What is the evidence?

Lipid Profile Perturbations Associated With Subclinical Hypothyroidism: A Descriptive Study

Background Hypothyroidism is a prevalent endocrine disorder associated with dyslipidemia, which increases cardiovascular risk. Our study aimed to estimate the prevalence of dyslipidemia and subclinical hypothyroidism (SCH) and their correlation in a diverse population. Methods A descriptive cross-sectional retrospective analysis was conducted to assess the prevalence of dyslipidemia in patients with SCH. Data were collected over 19 months from the Clinical Biochemistry Department of a Moroccan university hospital. A total of 447 patients were included based on comprehensive lipid profile and thyroid-stimulating hormone (TSH) assessments, and normal free thyroxine (FT4) levels. Lipid profile and TSH measurements followed standardized procedures using the Cobas Roche® 6000 system (Roche Diagnostics Corporation, Indianapolis, USA). Dyslipidemia and SCH were defined according to established thresholds recommended by reputable organizations. Statistical analyses were performed using SPSS version 23.0 (IBM Corp., Armonk, USA) and Microsoft Excel (Microsoft Corporation, Redmond, USA), with significance set at p < 0.05. Results In the total population (447 individuals), the prevalence of dyslipidemia was approximately 42.05% (N = 188), with hypoHDLemia being most prevalent at approximately 31.31% (N = 140). The prevalence of SCH was approximately 12.75% (N = 57), with women constituting approximately 7.6% and men approximately 5.15%. In the euthyroid group 1 (N = 390), the prevalence of dyslipidemia was approximately 40.76% (159 individuals), while in the hypothyroid group 2 (N = 57), it increased to approximately 50.87% (N = 29). Hypertriglyceridemia was more prevalent in Group 2, with a prevalence of approximately 21.05% (N = 12), compared to Group 1, which had a prevalence of approximately 13.84% (N = 54). Additionally, hypoHDLemia was notably higher in Group 2, with a prevalence of approximately 38.59% (N = 22), compared to Group 1, which had a prevalence of approximately 30.25% ( N = 118). The chi-square test revealed a significant association between SCH and dyslipidemia (χ2 = 1.427, p < 0.05). The calculated odds ratio (OR) of 1.5 (p < 0.05) indicates that individuals with SCH are 1.5 times more likely to have dyslipidemia compared to those without SCH. Conclusion In conclusion, our study provides valuable insights into the prevalence of dyslipidemia and its association with SCH in our patient population. We observed a notable prevalence of dyslipidemia among individuals with SCH, characterized by elevated levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). Importantly, while chi-square tests revealed a significant association between SCH and dyslipidemia, logistic regression analyses did not confirm a statistically significant correlation after adjusting for potential confounders.

A clinical decision support system for predicting coronary artery stenosis in patients with suspected coronary heart disease

Invasive coronary angiography imposes risks and high medical costs. Therefore, accurate, reliable, non-invasive, and cost-effective methods for diagnosing coronary stenosis are required. We designed a machine learning-based risk-prediction system as an accurate, noninvasive, and cost-effective alternative method for evaluating suspected coronary heart disease (CHD) patients. Electronic medical record data were collected from suspected CHD patients undergoing coronary angiography between May 1, 2017, and December 31, 2019. Multi-Class XGBoost, LightGBM, Random Forest, NGBoost, logistic models and MLP were constructed to identify patients with normal coronary arteries (class 0: no coronary artery stenosis), minimum coronary artery stenosis (class 1: 0 < stenosis <50%), and CHD (class 2: stenosis ≥50%). Model stability was verified externally. A risk-assessment and management system was established for patient-specific intervention guidance. Of 1577 suspected CHD patients, 81 (5.14%) had normal coronary arteries. The XGBoost model demonstrated the best overall classification performance (micro-average receiver operating characteristic [ROC] curve: 0.92, macro-average ROC curve: 0.89, class 0 ROC curve: 0.88, class 1 ROC curve: 0.90, class 2 ROC curve: 0.89), with good external verification. In class-specific classification, the XGBoost model yielded F1 values of 0.636, 0.850, and 0.858, for Classes 0, 1, and 2, respectively. The visualization system allowed disease diagnosis and probability estimation, and identified the intervention focus for individual patients. Thus, the system distinguished coronary artery stenosis well in suspected CHD patients. Personalized probability curves provide individualized intervention guidance. This may reduce the number of invasive inspections in negative patients, while facilitating decision-making regarding appropriate medical intervention, improving patient prognosis.

Update on subclinical thyroid dysfunction

Subclinical thyroid dysfunction is defined by serum thyroid-stimulating hormone (TSH) levels either greater or less than the reference range with normal thyroxine (T4) concentrations, and consists of subclinical hypothyroidism (SCH) and subclinical hyperthyroidism (SCHyper). For the proper diagnosis of SCH, it is most important to be able to correctly evaluate the serum TSH levels, which have numerous unique characteristics. We also need to be versed in TSH harmonization, which was recently launched world-wide. In this review, we will attempt to determine the best clinical approaches to the treatment of subclinical thyroid dysfunction based on recent guidelines published from several countries and novel findings of several recent large-scale clinical studies.

Subclinical Hypothyroidism in Advanced Chronic Kidney Disease Patients: Prevalence and Associated Factors

Introduction

Renal function and thyroid metabolism are tightly related. However, evidence about subclinical hypothyroidism prevalence in patients with chronic kidney disease and its related factors is scarce.

Objectives

Our aim is to analyze subclinical hypothyroidism prevalence and its related factors in patients with advanced chronic kidney disease. Materials and methods. Nondialysis-dependent patients with chronic kidney disease at stages 3 to 5 were included. Other inclusion criteria were age above 18 years and clinical stability. Patients with diagnosed thyroid illnesses were excluded. Subclinical hypothyroidism was defined as thyroid stimulating hormone (TSH) > 5.3 mU/L, with free thyroxine 4 (FT4) between 0.54 and 1.24 ng/dl. Filiation data, comorbidities, and routine blood and urine test results were registered.

Results

A total of 299 patients were included. Of them, 184 (61.5%) were men. The mean age was 71 ± 13 years old. The mean glomerular filtration rate (CKD-EPI) was 22 ± 9 ml/min/1.73 m². According to chronic kidney disease stages, global distribution of patients was as follows: Stage 3, 67 patients (22.4%); Stage 4, 155 patients (51.8%); and Stage 5, 77 patients (25.8%). We found subclinical hypothyroidism in 54 (18.1%) patients. According to chronic kidney disease stages, distribution of affected patients was as follows: Stage 3, 9 patients (13%); Stage 4, 25 patients (16.1%); and Stage 5, 20 patients (26%). Differences among stages were statistically significant. By univariate analysis, factors related with subclinical hypothyroidism were as follows: age RR 1.048 (95% CI 1.019–1.078; p=0.001), hypertension RR 2.705 (95% CI 1.026–7.130; p=0.04), glomerular filtration rate RR 0.962 (95% CI 0.929–0.996; p=0.03), and proteinuria higher than 1 gram/day RR 2.387 (95% CI 1.303–4.374; p=0.005). By multivariate analysis adjusted by age, hypertension, glomerular filtration rate, proteinuria, diabetes, and cardiovascular disease history, only age RR 1.016 (95% CI 1.009–1.028; p=0.04) and glomerular filtration rate RR 0.963 (95% CI 0.930–0.997; p=0.03) preserved their independent association with subclinical hypothyroidism.

Conclusions

Subclinical hypothyroidism prevalence in patients with chronic kidney disease is high and increases with renal disease severity. Factors independently related to subclinical hypothyroidism are age and glomerular filtration rate.

Low Urinary Iodine Concentration Is Associated with Increased Risk for Elevated Plasma Glucose in Females: An Analysis of NHANES 2011-12

Iodine intake in the US has declined in recent years. Iodine insufficiency increases the risk for inadequate thyroid hormone production and there is growing evidence that sub-clinical hypothyroidism may be disruptive to metabolic health, including insulin resistance (IR). We investigated the association between urinary iodine concentrations (UIC), a measurement of iodine status, and IR in adults. Data from 1286 US adults (≥20 years) in the NHANES 2011-2012 were analyzed. Two subgroups (low = UIC < 100 µg/L and normal = UIC ≥ 100 µg/L) were compared for markers of IR, including fasting plasma glucose (FPG) and insulin, homeostatic model assessment of insulin resistance (HOMA-IR), and glycated hemoglobin (HbA1C). Chi-square test, both linear and logistic regression models were used. In males, there were no significant associations between UIC and markers of IR; however, females with normal UIC had greater risks for elevated HOMA-IR (AOR = 0.56, 95% CI= 0.32-0.99) and HbA1C (AOR = 0.56, 95% CI = 0.34-0.90), while females with low UIC had a greater risk for FPG ≥ 5.6 mmol/L (AOR = 1.73, 95% CI = 1.09-2.72). Results only partially support our hypothesis that UIC is associated with the odds of IR in adults. The finding of an increased risk for elevated FPG, a marker of prediabetes, in female adults with low iodine status requires further investigation.

A Clinical Debate: Subclinical Hypothyroidism

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Characteristics of coronary artery disease in patients with subclinical hypothyroidism: evaluation using coronary artery computed tomography angiography

Background

Subclinical hypothyroidism (SCH) has recently been acknowledged as an independent risk factor for coronary artery disease (CAD). However, the characteristics of CAD in patients with SCH are not fully understood. This study aims to evaluate the features of CAD in patients with SCH using coronary computed tomographic angiography (CCTA).

Materials and methods

From 1 April, 2018 to 30 June, 2020, 234 consecutive SCH patients with coronary plaques identified on CCTA were included retrospectively. They were further subdivided into different degree of SCH groups (mild SCH vs. moderate SCH vs. severe SCH: 143 vs 62 vs 28) and different gender groups (men with SCH vs. women with SCH:116 vs 118). The distributions and types of plaques, luminal narrowing, segment involvement scores (SIS) and segment stenosis scores (SSS) were evaluated and compared among the different groups.

Results

Patients with severe SCH had fewer calcified plaques (0.7 ± 0.9 vs. 2.0 ± 1.9, p < 0.001) and more non-calcified plaques (0.9 ± 1.0 vs. 0.3 ± 0.5, p < 0.001) than those with mild SCH. As the SCH condition worsened, the proportion of non-calcified plaques significantly increased. Whereas there were no significant discrepancies in SIS and SSS among patients with different grades of SCH (all p > 0.05). Men with SCH had higher SIS (3.9 ± 2.3 vs. 3.0 ± 2.3, p = 0.004) and SSS (7.8 ± 5.4 vs. 5.4 ± 3.0, p = 0.002) than women. Multivariate logistic and linear regression analysis demonstrated that grades of SCH (Moderate SCH, odds ratio [OR] 2.11; 95% CI 1.03–4.34, p = 0.042; severe SCH, OR: 10.00; 95% CI 3.82–26.20, p < 0.001, taken mild SCH as a reference) was independently associated with the presence of non-calcified plaques, whereas sex (B: 1.67; 95% CI 0.27–3.10, p = 0.009) was independently associated with SSS.

Conclusions

Severe SCH is associated with non-calcified plaques, and men with SCH have higher total plaque burden than women. We suggest that it is important to evaluate for coronary plaque in SCH patients, especially those with severe SCH and men with SCH.

Effect of probiotic supplementation along with calorie restriction on metabolic endotoxemia, and inflammation markers in coronary artery disease patients: a double blind placebo controlled randomized clinical trial

Purpose

Alterations in the gut microbiome (dysbiosis) has been associated with increased microbial translocation, leading to chronic inflammation in coronary artery disease (CAD). It has been proposed that modulation of gut microbiota by probiotic might modify metabolic endotoxemia. Therefore, the purpose of this study was to examine the effects of Lactobacillus rhamnosus GG (LGG) on endotoxin level, and biomarkers of inflammation in CAD participants.

Methods

This study was a 12-weeks randomized, double-blind, and intervention on 44 patients with CAD. Patients were randomly allocated to receive either one LGG capsule 1.6 × 10⁹ colony-forming unit (CFU) or the placebo capsules for 12 weeks. In addition, all the participants were also prescribed a calorie-restricted diet. Serum levels of interleukin-1β (IL-1β), Toll-like receptor 4 (TLR4), interleukin-10 (IL-10), and lipopolysaccharide (LPS), were assessed before and after the intervention.

Results

A significant decrease in IL1-Beta concentration (− 1.88 ± 2.25, vs. 0.50 ± 1.58 mmol/L, P = 0.027), and LPS levels (− 5.88 ± 2.70 vs. 2.96+ 5.27 mg/L, P = 0.016), was observed after the probiotic supplementation compared with the placebo. Participants who had ≥2.5 kg weight loss showed significantly improved cardiovascular-related factors, compared to patients with < 2.5 kg weight reduction, regardless of the supplement they took.

Conclusion

These data provide preliminary evidence that probiotic supplementation has beneficial effects on metabolic endotoxemia, and mega inflammation in participants with CAD.

Common Electrolyte and Metabolic Abnormalities Among Thyroid Patients

The prevalence of thyroid diseases is high in the general population and causes serious abnormalities and disorders that can affect the quality of life. Many complications can result from poor or inappropriate management of the disease, leading to serious cardiovascular and metabolic complications. In the present review study, we aim to discuss the effect of thyroid diseases on metabolic and electrolyte abnormalities and the potential correlation with some common disorders. Evidence from previous studies has demonstrated that thyroid dysfunctions hugely affect the metabolism of glucose in the bodies of the affected patients, which can lead to the development of both type 1 and 2 diabetes mellitus (DM). Hyperthyroidism can lead to the development of impaired glucose tolerance and secondary diabetes mellitus. These include an increased glycogenolysis and gluconeogenesis process, increased intestinal absorption of glucose, and secondary ketogenesis and lipolysis, which will subsequently affect the functions of the insulin-secreting cells of the pancreas. Evidence showed that thyroid diseases are associated with the development of obesity and metabolic syndrome, and the management for these modalities should involve prior management of underlying thyroid diseases. Efforts should be made to adequately manage these cases with concomitant approaches to achieve the best clinical outcomes.

Unfavorable Triglyceride-rich Particle Profile in Subclinical Thyroid Disease: A Cross-sectional Analysis of ELSA-Brasil

Subclinical thyroid disorders have been associated with atherosclerosis and increased cardiovascular risk. As triglyceride-rich lipoprotein particles (TRLPs) have recently emerged as a casual factor for atherogenesis, the aim of this study was to evaluate the relationship between subclinical hypo- and hyperthyroidism and TRLP subfractions. We selected 5066 participants from the ELSA-Brasil cohort with available data of thyroid function and lipid profile measured by nuclear magnetic resonance (NMR) spectroscopy. Individuals were divided into 3 groups by baseline thyroid function (subclinical hypothyroidism, euthyroidism, and subclinical hyperthyroidism). Triglyceride-rich lipoprotein particle subfractions were analyzed through NMR spectroscopy. To examine the association between TRLP subfractions and thyroid function, we conducted univariate and multivariate linear regression models adjusted for demographic characteristics, body mass index, diabetes, smoking status, and alcohol use. Of 3304 individuals, 54% were women, with a mean age of 50.6 ± 8.7 years, 51% white, and 53% with at least a college education. Of these individuals, 92% were euthyroid, whereas 6.8% had subclinical hypothyroidism and 1.2% had subclinical hyperthyroidism. The univariate linear regression showed that very small TRLPs (P = 0.026) and very large TRLPs (P = 0.008) were statistically increased in subclinical hypothyroidism when compared with euthyroidism. In subclinical hyperthyroidism, there was a reduction in total TRLPs (P = 0.003), seemingly driven by reduced very small TRLPs (P = 0.067). The findings were confirmed when adjusted for demographic characteristics, as well as comorbidities. This study suggests that subclinical hypothyroidism is associated with very small and very large TRLPs, which are related to an unfavorable atherogenic profile. Subclinical hyperthyroidism is associated to lower very small TRLPs.

Plasma Lipid Profile and Intestinal Microflora in Pregnancy Women With Hypothyroidism and Their Correlation With Pregnancy Outcomes

OBJECTIVE

To investigate the lipid profiles and intestinal microflora in pregnant patients with hypothyroidism and their correlation with pregnancy outcomes.

METHODS

In total, 27 pregnant women with hypothyroidism (study case) and 28 normal pregnant women (control group) were enrolled in this study. The lipid profiles and intestinal microflora in the two groups were compared using untargeted liquid chromatography-mass spectrometry (LC-MS) and 16S rRNA amplicon sequencing, respectively. The association among the differential metabolites, intestinal microflora, serological indicators and pregnancy outcomes was further analyzed.

RESULTS

Patients in study case had higher C-reactive protein (CRP) levels (P = 0.025) and lower birth weight (P=0.005) than the control group. A total of 42 differential lipid metabolites and 7 enrichment KEGG pathways were obtained between the two groups (VIP ≥ 1, P < 0.05). Ten lipid metabolites can be used as characteristic metabolites of study case, including phosphatidylcholine (PC), phosphatidylethanolamine (PE) and sphingomyelin (SM). The richness and diversity of intestinal microflora in study case were lower than those in the control group (P>0.05). LEfSe analysis revealed that patients in study case had higher abundance of Prevotella and Haemophilus and lower abundance of Blautia than the control group (P < 0.05). Blautia was positively correlated with SM and negatively correlated with PC and PE; the CRP level and Prevotella were positively correlated; the neonatal weight and PC level were negatively correlated (P < 0.05).

CONCLUSION

The lipid profile and intestinal microflora of pregnant women with hypothyroidism significantly differed from those of normal pregnant women and were associated with adverse pregnancy outcomes. The interaction between lipid metabolism and intestinal microflora may be a potential target for further studies investigating the pathogenesis of hypothyroidism during pregnancy.

ATHEROGENIC INDICES IN THE ASSESSMENT OF CARDIOVASCULAR DISEASE RISK IN CHILDREN WITH OBESITY AND SUBCLINICAL HYPOTHYROIDISM

Background

The frequency of subclinical hypothyroidism (SH) in patients with obesity is increased compared with the normal population. However, data on the risk of cardiovascular disease (CVD) in patients with SH are still scarce. Lipid parameters are strong predictors of early CVD. We aimed to investigate the role of lipid indices in predicting CVD risk compared to conventional lipid components.

Methods

A total of 220 euthyroid obese children (EU) and 90 obese children with SH were included in the study. All data were collected from hospital files. Lipid indices were evaluated. Atherogenic index of plasma (AIP), cardiac risk ratio (CRR) and atherogenic coefficient (AC) were calculated. AIP>0.24, CRR>5 ve AC>3 were considered as cardiovascular risk criteria.

Results

The presence of SH increased the risk of higher AIP and the risk of CRR, compared to euthyroid obese children.

Conclusion

Subclinical hypothyroidism in obese children may cause dislipidemia carrying a high cardiovascular disease risk.

Differences in HDL particle size in the presence of subclinical thyroid dysfunctions: The ELSA-Brasil study

BACKGROUND AND AIMS

Thyroid dysfunction is related to several lipid abnormalities. There is no consensus about concentration of high-density lipoprotein (HDL) in different studies. The aim of this report is to evaluate HDL particle (HDL-P) subfractions across a spectrum of thyroid functions in a Brazilian population.

METHODS

Individuals were divided into three groups by baseline thyroid function (subclinical hypothyroidism, euthyroidism, and subclinical hyperthyroidism). HDL-P subfractions were analyzed by Nuclear Magnetic Resonance (NMR) spectroscopy. To examine the association between HDL-P subfractions and thyroid function, we used univariate and multivariate linear regression models adjusted for demographic characteristics, comorbidities, lifestyle factors, and traditional lipid measurement (HDL-C, LDL-C and triglycerides).

RESULTS

Of 3304 participants, 54.1% were women, 51.2% white, with mean age 50.6 ± 8.7 years. HDL-C and triglycerides levels (p = 0.032 and p = 0.016, respectively) were higher in the SC hypothyroid group. There were no statistically significant differences in total cholesterol levels and LDL-C levels. In univariate analysis, small HDL-P subfractions were significantly lower in subclinical hypothyroidism (p = 0.026) whereas intermediate HDL-P were higher in subclinical hyperthyroidism (p = 0.049), compared to euthyroidism. After adjustment for demographic data, SC hypothyroidism was still statistically associated with lower levels of small HDL-P. After adjusting for comorbidities, lifestyle factors, and traditional lipid measurements, SC hypothyroidism had an established association with lower levels of small HDL-P while SC hyperthyroidism was associated with lower levels of large HDL-P.

CONCLUSIONS

In this large cohort from a Brazilian population, subclinical hypothyroidism was associated with lower small HDL-P subfractions, and subclinical hyperthyroidism with lower large HDL-P subfractions and higher intermediate HDL-P subfractions.

Sex differences in subclinical hypothyroidism and associations with metabolic risk factors: a health examination-based study in mainland China

BACKGROUND

The association between subclinical hypothyroidism (SCH) and metabolic risk factors in the general health examination-based population has been widely explored. However, the results have been inconclusive. Additionally, the sex differences in the prevalence of SCH and the association of SCH with metabolic risk factors remain unknown.

METHODS

We conducted this cross-sectional study using data from health examination-based participants between June 2016 and April 2018 in our health examination centre. Sex differences SCH and the association of SCH with metabolic risk factors were explored.

RESULTS

The total prevalence of SCH was 3.40% among the 5319 included participants, and 4.90% among the 2306 female participants, which was much higher than the prevalence of 2.26% among the 3013 male participants (p < 0.05). In males, the difference between participants younger than 60 and aged 60 or older was not significant (p = 0.104); while in females, the difference between participants younger than 40 and participants aged 40 or older was statistically significant (p = 0.023). Multivariate logistic regression analysis demonstrated that age (OR = 0.568, p = 0.004), body-mass index (BMI) (OR = 5.029, p < 0.001) and systolic/diastolic blood pressure (SBP/DBP) (OR = 5.243, p < 0.001) were independent predictors of SCH in females, but no metabolic risk factor was significantly associated with SCH in males. Further analysis revealed that the prevalence was much higher in participants with one or two metabolic risk factors than in those with no above metabolic risk factors regardless of age (p < 0.01).

CONCLUSIONS

Our study demonstrates that high BMI and/or high blood pressure are associated with SCH in female participants, and the prevalence of SCH among women with one or two metabolic risk factors ranges from 7.69-14.81%, which indicates that in such a population, serum concentrations of TSH and FT4 may be routinely screened in mainland China. Certainly, prospective, large-scale studies with long follow-up period are still necessary to further verify our results.

Association Between High-Sensitivity C-Reactive Protein and Idiopathic Adhesive Capsulitis

BACKGROUND

Chronic inflammation is implicated in the development of idiopathic adhesive capsulitis (IAC), whose association with high-sensitivity C-reactive protein (CRP), an inflammation marker, is undetermined. This study's purposes were to investigate the association between high-sensitivity CRP levels and IAC and to determine the metabolic factors associated with high-sensitivity CRP.

METHODS

This case-control study examined a group of 202 patients with IAC and without intrinsic shoulder lesions or extrinsic causes and a control group of 606 age and sex-matched persons seeking general check-ups at our health promotion center during the same period as the case group. Control subjects had normal shoulder function and no previously diagnosed adhesive capsulitis; no medication for diabetes, dyslipidemia, and thyroid abnormalities; and no history of trauma or of shoulder surgery. The studied variables were body mass index; diabetes; thyroid abnormalities; dyslipidemias; triglyceride/high-density lipoprotein (TG/HDL) >3.5; serum levels of thyroid hormone, fasting glucose, and glycosylated hemoglobin A1c (HbA1c); and high-sensitivity CRP >1.0 mg/L. Multivariable conditional logistic regression analysis evaluated the matched sets of subjects. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined for the studied variables possibly affecting IAC.

RESULTS

Serum high-sensitivity CRP >1.0 mg/L was significantly associated with IAC (OR, 2.47 [95% CI, 1.65 to 3.70]) after adjusting for diabetes, fasting glucose level, HbA1c, dyslipidemia, TG/HDL >3.5, and thyroid-stimulating hormone (p ≤ 0.031). Diabetes (OR, 1.71 [95% CI, 1.09 to 3.33]), fasting glucose level (OR, 1.54 [95% CI, 1.12 to 2.12]), HbA1c (OR, 2.00 [95% CI, 1.25 to 3.22]), hypertriglyceridemia (OR, 1.70 [95% CI, 1.03 to 3.41]), hypo-high-density lipoproteinemia (OR, 1.98 [95% CI, 1.04 to 3.79]), and TG/HDL >3.5 (OR, 1.37 [95% CI, 1.06 to 1.88]) were significantly associated with high-sensitivity CRP >1.0 mg/L in patients with IAC (p ≤ 0.039).

CONCLUSIONS

Serum high-sensitivity CRP >1.0 mg/L is an independent associated marker for IAC. Dyslipidemia, insulin resistance, and hyperglycemia, which are recognized factors associated with IAC, are also associated with high-sensitivity CRP >1.0 mg/L in these patients, supporting the interaction of chronic systemic inflammation in IAC.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Slit2 May Underlie Divergent Induction by Thyrotropin of IL-23 and IL-12 in Human Fibrocytes

IL-23 and IL-12, two structurally related heterodimeric cytokines sharing a common subunit, divergently promote Th cell development and expansion. Both cytokines have been implicated in the pathogenesis of thyroid-associated ophthalmopathy (TAO), an autoimmune component of Graves disease. In TAO, CD34+ fibrocytes, putatively derived from bone marrow, can be identified in the orbit. There they masquerade as CD34+ orbital fibroblasts (OF) (CD34+ OF) and cohabitate with CD34- OF in a mixed fibroblast population (GD-OF). Slit2, a neural axon repellent, is expressed and released by CD34- OF and dampens the inflammatory phenotype of fibrocytes and CD34+ OF. In this study we report that thyrotropin (TSH) and the pathogenic, GD-specific monoclonal autoantibody, M22, robustly induce IL-23 in human fibrocytes; however, IL-12 expression is essentially undetectable in these cells under basal conditions or following TSH-stimulation. In contrast, IL-12 is considerably more inducible in GD-OF, cells failing to express IL-23. This divergent expression and induction of cytokines appears to result from cell type-specific regulation of both gene transcription and mRNA stabilities. It appears that the JNK pathway activity divergently attenuates IL-23p19 expression while enhancing that of IL-12p35. The shift from IL-23p19 expression in fibrocytes to that of IL-12p35 in their derivative CD34+ OF results from the actions of Slit2. Thus, Slit2 might represent a molecular determinant of balance between IL-23 and IL-12 expression, potentially governing immune responses in TAO.

Prevalence of hypothyroidism among chronic kidney disease patients in security force hospital (SFH) in Saudi Arabia

Introduction:

Impairment in kidney function leads to disturbed thyroid physiology. All levels of the hypothalamic-pituitary-thyroid axis may be involved, including alterations in hormone production, distribution, and excretion, and even CKD progress with hypothyroidism.

Aim of Work:

To assess the prevalence of hypothyroidism among chronic kidney disease patients.

Materials and Methods:

A cross-sectional analysis was conducted in the nephrology department of security forces hospital from January 2015 to February 2018. Biochemical tests (includes blood urea, serum creatinine, PTH, total T4, TSH) were carried out to all participants.

Results:

Out of 255 CKD patients in the present study, 166 patients had no hypothyroidism, 43 had subclinical hypothyroidism, and 46 had hypothyroidism. The percentage of hypothyroidism among CKD patients was 34.9%, including dialysis patients and 17.66% after exclusion. Out of 24 peritoneal dialysis patients in the current study (P = 0.03), 7 had subclinical hypothyroidism and another 7 had hypothyroidism. In addition, out of 139 hemodialysis patients (P = 0.02), 20 patients had subclinical hypothyroidism and 18 had hypothyroidism. The majority (67.36%) of CKD patients were in CKD stage 5 and had no hypothyroidism (45.10%). Only 29 (11.37%) patients in CKD stage 5 had hypothyroidism and 28 (10.89%) patients had subclinical hypothyroidism. T4 was higher in nondialysis patients, whereas TSH and PTH were higher in dialysis patients.

Conclusion:

The prevalence of hypothyroidism among chronic kidney disease patients was high and increased with the decrease in estimated GFR.

Thyroid hormone therapy in congenital hypothyroidism and pediatric hypothyroidism

The evaluation and management of hypothyroidism in children are similar to adults, but there are important differences based on the dependence on normal thyroid function for neurocognitive and physical development. In the pediatric population, hypothyroidism is frequently categorized as congenital or acquired hypothyroidism, depending on the age of presentation and the underlying etiology. The evaluation and management of children and adolescents with hypothyroidism are determined by the etiology as well as by the age at diagnosis, severity of the hypothyroidism, and the response to thyroid hormone replacement therapy. Children and adolescents require higher weight-based doses for thyroid hormone replacement than do adults, likely due to a shorter half-life of thyroxine (T4) and triiodothyronine (T3) in children, but weight-based dose requirements decrease as the child advances into adulthood. Multiple gaps in knowledge remains regarding how to optimize the treatment of hypothyroidism in pediatric patients, including (but not limited to) the selection of patients with subclinical hypothyroidism for treatment, and the potential benefit of combined LT3/LT4 therapy for patients with persistent symptoms and/or low T3 on LT4 monotherapy. The life-long impact on growth and development, and potentially on long-term cardiovascular and psychosocial health, are significant and highlight the importance of future prospective studies in pediatric patients to explore these areas of uncertainty.

Diagnosis and treatment of hypothyroidism in the elderly

The global population is aging with millions of people today living into their 90 s. Thyroid disease, particularly hypothyroidism, is widespread among all age groups, and it is expected to steadily increase as the population gets older. Clinical diagnosis of hypothyroidism is challenging, as the TSH reference range needs to be evaluated according to age, while evaluation of TSH levels must also take into account body weight and other variants such as polypharmacy, comorbidities, and general health condition. Since thyroid hormone has a potent regulatory effect on cholesterol metabolism, the possibility of thyroid dysfunction should be considered in cases of unexplained dyslipidemia. Once hypothyroidism has been confirmed, treatment requires caution, frequent cardiovascular monitoring, and individualized (precision) medicine. Treatment of subclinical hypothyroidism (SCH) in the elderly should be undertaken with care, guided by age and the degree of SCH: a TSH higher than 10 mU/l seems a reasonable threshold, though it should be regularly re-evaluated, while the LT4 dose needs to be tailored, taking into account the patient's health condition and the potential presence of dyslipidemia as well as other metabolic derangements.

Evaluation of cardiovascular risk by growth-differentiation factor-15 and tissue Doppler imaging in children with subclinical hypothyroidism

OBJECTIVE

Subclinical hypothyroidism, defined as increased TSH serum levels and normal serum free T4 concentrations, has been associated with an increased risk of heart disease in adults. But, data in children and adolescents are scanty and treatment of subclinical hypothyroidism is controversial. Growth differentiation factor-15 (GDF-15) is a promising biomarker of cardiac remodeling. This study aimed to evaluate the cardiovascular risk factors in children with subclinical hypothyroidism, measured with tissue Doppler echocardiography (TDE), and conventional echocardiography and GDF-15 level.

METHODS

The study comprised a total of 41 pediatric patients with subclinical hypothyroidism (SH) (mean age 9.6 ± 4.7 years) and 31 healthy children (mean age 11.2 ± 3.4 years) as the control group. Subclinical hypothyroidism was defined as a thyroid-stimulating hormone level higher than 4 mIU/l and a normal free-thyroxine level (0.6-1.8 ng/dl). Tissue Doppler echocardiography was performed to all individuals in the control group and patient group at the beginning of the study. Global systolic function as assessed by left ventricular ejection fraction was compared between groups. The serum GDF-15 level was measured.

RESULTS

There were no significant differences in demographic parameters between the SH and control groups. The left ventricular internal diameter end systole, interventricular septal end diastole, left ventricular posterior wall end diastole, and tricuspid annular plane systolic excursion values were significantly different between the SH and control groups (p = 0.038, 0.028, 0.005, and 0.000, respectively). The mean mitral isovolumic relaxation time value of the SH group was 57.2 ± 9.3 ms, compared to 44.5 ± 5.6 ms for the control group (p = 0.000). The mean tricuspid isovolumic contraction time value of the SH group was 58.7 ± 9.4 ms, and that of the control group was 45.1 ± 5.3 ms (p = 0.000). The mean tricuspid isovolumic relaxation time value of the SH group was 58.03 ± 9.5 ms, and that of the control group was 45.1 ± 5.3 ms (p = 0.000). There were no significant differences in the other m-mode or pulse Doppler echocardiography values between two groups. The GDF-15 value of the SH group was 382.6 ± 268.2 pg/mL, and that of the control group was 473.6 ± 337.9 pg/mL; this difference was not significant.

CONCLUSION

Patients with subclinical hypothyroidism versus healthy individuals had some changes in echocardiographic parameters that indicate involvement of diastolic function of the left ventricle. They were significantly different when compared SH group and the control group. This study demonstrated ventricle diastolic dysfunction in pediatric patients with hypothyroidism. The results of our study suggest that cardiac follow-up may be useful in patients with subclinical hypothyroidism and clinical trials are needed to explore therapeutic effects of T4 and T3 administration in this patients.

Evaluation of the relationship of subclinical hypothyroidism with metabolic syndrome and its components in adolescents: a population-based study

PURPOSE

This study investigated the association of subclinical hypothyroidism (SCH) with metabolic syndrome (MetS) and its components in adolescents.

METHODS

The study population included 1006 adolescents (aged 10-18 years) from the Korea National Health and Nutrition Examination Surveys; SCH subjects were compared with euthyroid subjects. MetS was defined using the International Diabetes Federation criteria. The risks of MetS and its components in SCH and euthyroid subjects were calculated using binary logistic regression analyses.

RESULTS

Study subjects had a mean age of 14.2 ± 2.5 years, and 53% were male. The prevalence of MetS was 2.5% in the overall study population (3.2% of males and 1.7% of females). Among the 1006 subjects, 143 (14.2%) had SCH. The risk of MetS was not higher in SCH subjects than in euthyroid subjects (odds ratio [OR], 1.50; 95% confidence interval [CI], 0.54-4.11); however, among the components of MetS, the risk of abdominal obesity was higher in SCH subjects than in euthyroid subjects (OR, 2.08; 95% CI, 1.04-4.15) after adjusting for age, sex, and body mass index (BMI). Although not statistically significant, a trend toward increased risk of elevated blood pressure (BP) was observed in SCH subjects relative to euthyroid subjects after further adjusting for age, sex, and BMI (OR, 2.01; 95% CI, 0.89-4.52). Furthermore, non-obese SCH subjects had higher systolic BP compared with non-obese euthyroid subjects after adjusting for age, sex, and BMI (P = 0.014).

CONCLUSIONS

SCH was not associated with the presence of MetS. However, SCH may be associated with abdominal obesity and possibly elevated BP in adolescents.

Thyroid Dysfunction and Diabetes Mellitus: Two Closely Associated Disorders

Thyroid dysfunction and diabetes mellitus are closely linked. Several studies have documented the increased prevalence of thyroid disorders in patients with diabetes mellitus and vice versa. This review critically discusses the different underlying mechanisms linking type 1 and 2 diabetes and thyroid dysfunction to demonstrate that the association of these two common disorders is unlikely a simple coincidence. We assess the current state of knowledge on the central and peripheral control of thyroid hormone on food intake and glucose and lipid metabolism in target tissues (such as liver, white and brown adipose tissue, pancreatic β cells, and skeletal muscle) to explain the mechanism linking overt and subclinical hypothyroidism to type 2 diabetes and metabolic syndrome. We also elucidate the common susceptibility genes and the pathogenetic mechanisms contributing to the autoimmune mechanism involved in the onset of type 1 diabetes mellitus and autoimmune thyroid disorders. An untreated thyroid dysfunction can impair the metabolic control of diabetic patients, and this association can have important repercussions on the outcome of both of these disorders. Therefore, we offer recommendations for the diagnosis, management, and screening of thyroid disorders in patients with diabetes mellitus, including the treatment of diabetic patients planning a pregnancy. We also discuss the major causes of failure to achieve an optimal management of thyroid dysfunction in diabetic patients and provide recommendations for assessing and treating these disorders during therapy with antidiabetic drugs. An algorithm for a correct approach of these disorders when linked is also provided.

The influence of subclinical hypothyroidism on serum lipid profile, PCSK9 levels and CD36 expression on monocytes

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease and a secreted protein which increases cholesterol levels in plasma via inducing degradation of low-density lipoprotein receptor (LDLR). Cluster of differentiation 36 (CD36) is a member of a family of cell surface proteins in many cells. CD36 is known as fatty acid translocase (FAT) because it imports fatty acids inside cells and participate in triglyceride storage. It has been suggested that PCSK9 regulates CD36 in some tissues.

METHODS

Data and serum levels of TSH, FT4, lipid profile and PCSK9 and the expression of CD36 on monocytes from 40 new untreated patients with subclinical hypothyroidism (SH) and 40 age- sex- and BMI-matched euthyroid controls were analyzed in a cross-sectional study. Then the relationships between these parameters were examined.

RESULTS

Patients with SH had higher TSH, FT4, total cholesterol (TC) and triglyceride (TG) Low-density lipoprotein (LDL) and PCSK9 levels than controls. There were significant and positive correlations between serum TSH levels and lipid parameters except HDL-C. PCSK9 had a significant and negative correlation with FT4. No significant correlation could be found in relation to PCSK9 and CD36.

CONCLUSIONS

PCSK9 inhibitors are used to reduce blood cholesterol levels as drugs. If it will be proven that PCSK9 can induce CD36 degradation, taking these drugs may have unwanted side effects. This study showed that serum PCSK9 and lipid profile levels increase in patients with subclinical hypothyroidism and there is no relationship between PCSK9 and CD36 in these patients.

Mild subclinical hypothyroidism is associated with paediatric dyslipidaemia

BACKGROUND

There is a lack of consensus on the cardiometabolic consequences of mild subclinical hypothyroidism (SCH) among children. The objective of the current study was to compare lipid profiles in children with mild SCH with those of euthyroid children.

STUDY DESIGN

Retrospective medical record review.

PATIENTS

Children (ages 2-18 years) who had undergone simultaneous measurement of TSH, free thyroxine (T4) and lipids. Lipids in children with mild SCH (TSH 5-<10 mIU/L and normal free T4, n = 228) were compared with those in euthyroid children (n = 1215).

RESULTS

TSH level was positively associated with total cholesterol and nonhigh density lipoprotein (non-HDL) cholesterol [β 0.05(0.03-0.08), P < .0001 and β 0.05(0.03-0.08), P < .0001, respectively]. Total cholesterol was significantly higher in children and adolescents with mild SCH compared with euthyroid children (4.43 ± 1.14 mmol/L vs 4.2 ± 0.85 mmol/L, P = .0005). Similarly, non-HDL cholesterol level was also higher in children with mild SCH relative to euthyroid children (3.08 ± 1.14 mmol/L vs 2.91 ± 0.8 mmol/L, P = .001). The adjusted odds ratio of having elevated total cholesterol and elevated non-HDL cholesterol was greater in children with mild SCH compared with euthyroid children (OR 1.88, 95% CI; 1.28-2.73; P = .001 and 1.72, 95% CI 1.2-2.5; P = .003, respectively). The presence of thyroid autoimmunity was not associated with higher rates of dyslipidaemia.

CONCLUSIONS

Mild SCH in children and adolescents was associated with higher rates of elevated total cholesterol and elevated non-HDL cholesterol. Randomized placebo controlled studies are warranted to determine if treatment of mild SCH in children leads to improvement in lipid profile.

Association of metabolic risks with subclinical hypothyroidism: A cross-sectional analysis

Objective:

To compare lipid parameters, HbA1c, uric acid and albumin creatinine ratio (UACR) among subjects having euthyroidism, Sub-Clinical Hypothyroidism (SCH) and overt hypothyroidism.

Methods:

This comparative cross-sectional analysis was carried out from Dec-2015 to Oct-2016 in collaboration between PNS HAFEEZ hospital and department of chemical pathology and endocrinology, Armed Forces Institute of Pathology, Rawalpindi. Biochemical parameters including lipid indices, HbA1c and UACR were compared between euthyroidism (TSH: 0.5 to 4.0 mIU/L, n=163), subclinical hypothyroidism (TSH: 4.0 to 10 mIU/L, n=16) and overt hypothyroidism (TSH:≥ 10.0 mIU/L, n=9).

Results:

LDL-cholesterol, non-HDL-cholesterol and UACR results were as: [(Euthyroid: 2.66 ± 0.73), (SCH: 2.68 ± 0.51) and (Overt hypothyroidism: 3.23 ± 0.59), p-value=0.063], [(Euthyroid: 3.49 ± 0.64), (SCH: 3.35 ± 0.59) and (Overt hypothyroidism: 4.01 ± 0.30), p-value=0.033] and [{Euthyroid: 2.48 (95% CI: 1.63-3.33)}, {SCH: 2.27 (95% CI: 0.37-4.90)} and {Overt hypothyroidism: 14.95 (95% CI: 10.71-19.14){, (p-value< 0.001)] Results for total cholesterol, triglycerides and HDL-cholesterol though increased in overt hypothyroid group were not found to be statistically significant.

Conclusion:

LDL-cholesterol, non-HDL-cholesterol and UACR increased from euthyroid subjects to overt hypothyroidism group. However, these changes were found to be more subtle in the subclinical hypothyroid subjects than cases with overt hypothyroidism.

Subclinical hypothyroidism and metabolic risk factors association: A health examination-based study in northern Taiwan

Background

Subclinical hypothyroidism (SCH) is defined as elevation in serum thyroid-stimulating hormone (TSH) levels despite normal serum levels of free thyroxine. It remains controversial whether people with SCH have higher total cholesterol and low-density lipoprotein cholesterol levels compared to normal-thyroid subjects. The aim of this study was to assess the metabolic risk factors for SCH.

Methods

Subjects were recruited from the health examination center of Chang Gung Memorial Hospital, Linkou, from January 1, 2010 to December 31, 2011. This was a cross-sectional review of medical records. The subjects were ethnic Taiwanese residents without known thyroid disease at baseline.

Results

A total of 22,324 subjects received annual health examination at Chang Gung Memorial Hospital from 2010 to 2011. Among them, 15,943 subjects were included as the normal thyroid group (NG), and 203 subjects (101 men and 102 women) met the criteria for SCH. The prevalence of metabolic syndrome (MetS) in the NG was 26.2% in men and 18.7% in women, whereas that in the SCH group was 39.6% in men and 29.4% in women. Women in the SCH group showed significantly higher cholesterol, triglyceride, non-high density lipoprotein (HDL) and cholesterol/HDL levels than those in the NG (p < 0.05).

Conclusion

Because SCH is more prevalent in women and the risk increases with age, greater attention to the risk of MetS development is warranted. As for men, regardless of thyroid function, the risk of MetS development with age still warrants attention. Thus, our data suggest that national guidelines for screening for thyroid disease using serum TSH levels in the elderly are mandatory.

For better or worse: Immune system involvement in Alzheimer's Disease

In this issue of the Biomedical Journal, we explore the key role of the immune system in the development of Alzheimer's disease. We also learn more about the link between two disorders related to metabolic imbalances, with findings that could help to inform future screening programs. Finally, we would like to highlight some big news for our journal: the Biomedical Journal will be indexed in the Science Citation Index and receive its first official impact factor from this year.

Current Helicobacter pylori infection is significantly associated with subclinical coronary atherosclerosis in healthy subjects: A cross-sectional study

Helicobacter pylori is a gastrointestinal pathogen known to be associated with cardiovascular disease (CVD). However, most analyses about the effect of H. pylori infection have been done in patients with a history of CVD but not in healthy subjects. We evaluated the association between H. pylori infection and subclinical atherosclerosis by using cardiac multidetector computed tomography (MDCT) in healthy subjects without previous CVD. From December 2007 to February 2014, 463 subjects who underwent the rapid urease test (CLO test), pulse-wave velocity (PWV) measurement, and MDCT for a self-referred health check-up were enrolled to this study. Helicobacter pylori infection was defined on the basis of CLO test positivity on endoscopic gastric biopsy. Significant coronary artery stenosis was defined as ≥50% stenosis in any of the major epicardial coronary vessel on MDCT. The CLO-positive subjects had a lower high-density lipoprotein-cholesterol (HDL-cholesterol) level compared to the CLO-negative subjects. The incidence of significant coronary stenosis was higher in the CLO-positive group (7.6% vs. 2.9%, P = 0.01). Furthermore, the number of subjects with coronary artery calcium score >0 and log{(number of segments with plaque)+1} were also significantly higher in the CLO-positive group. However, there was no statistical difference in the number of subjects with coronary artery calcium score >100, the prevalence of any plaque nor the plaque characteristics (calcified, mixed, or soft). Pulse-wave velocity (PWV) was neither associated with CLO test positivity. The CLO-positive group was 3-fold more likely to have significant coronary artery stenosis even after adjusting for confounding factors (adjusted odds ratio 2.813, 95% confidence interval 1.051–7.528, P = 0.04). In a healthy population, current H. pylori infection was associated with subclinical but significant coronary artery stenosis. The causal relationship between H. pylori infection and subclinical atherosclerosis in a “healthy” population remains to be investigated in the future.

Subclinical hypothyroidism in children: is it always subclinical?

Aim of this commentary is to report current knowledges on the main clinical and metabolic abnormalities which might be observed in children with longstanding and untreated subclinical hypothyroidism (SH) and to comment the most recent views about natural evolution of thyroid function in the cases with either idiopathic or Hashimoto’s thyroiditis-related SH. On the basis of these preliminary remarks, the essential guidelines for an appropriate and tailored management of SH children are also proposed.

Effects of Thyrotropin on Peripheral Thyroid Hormone Metabolism and Serum Lipids

BACKGROUND

Subclinical hypothyroidism is associated with dyslipidemia and atherosclerosis. Whether these effects are in part mediated via direct effects of thyrotropin (TSH) on peripheral thyroid hormone (TH) metabolism and/or concentrations of serum lipids is not clear.

OBJECTIVE

This study examined whether TSH has direct effects on peripheral TH metabolism and serum lipids.

METHODS

Eighty-two patients with differentiated thyroid cancer were retrospectively analyzed. All patients had undergone total thyroidectomy and ¹³¹I remnant ablation. During follow-up, two successive injections of recombinant human TSH (rhTSH) were administered to patients on a stable dose of levothyroxine. In all patients, TSH, thyroxine (T4), free T4 (fT4), triiodothyronine (T3), reverse T3 (rT3), total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, apolipoprotein B, lipoprotein(a), and triglyceride levels were measured immediately before the first and approximately 72 hours after the second injection of rhTSH.

RESULTS

After rhTSH stimulation, T3 values decreased (from 1.91 to 1.81 nmol/L; p < 0.001). T4, fT4, and rT3 did not change. After rhTSH, median apolipoprotein B increased from 0.90 to 0.92 g/L (p = 0.03), lipoprotein(a) from 0.21 to 0.24 g/L (p < 0.001), and triglycerides from 1.98 to 2.50 mmol/L (p < 0.001). Serum high-density lipoprotein cholesterol decreased from 0.98 to 0.81 mmol/L (p < 0.001). Multiple regression analysis showed that the changes in lipids were most closely associated with the decrease in T3 levels.

CONCLUSIONS

TSH has direct effects on peripheral TH metabolism by decreasing T3 levels in levothyroxine-treated thyroidectomized patients. This decrease in T3 levels is accompanied by unfavorable changes in serum lipids.

A Renewed Focus on the Association Between Thyroid Hormones and Lipid Metabolism

Thyroid dysfunction, manifesting as either overt or subclinical hypothyroidism, negatively affects lipid metabolism: this leads to hypercholesterolemia which progressively increases the risk for cardiovascular disease and, potentially, mortality. Hypercholesterolemia in hypothyroidism is mainly due to a reduction in low-density lipoprotein (LDL) receptor activity, this accompanied by concomitant diminishing control by triiodothyronine (T3) of sterol regulatory element-binding protein 2 (SREBP-2), which modulates cholesterol biosynthesis by regulating rate-limit degrading enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA) activity. Recently, 3,5-diiodothyronine (T2), a natural thyroid hormone derivative, was found to repress the transcription factor carbohydrate-response element-binding protein (ChREBP) and also to be involved in lipid catabolism and lipogenesis, though via a different pathway than that of T3. While thyroid hormone could therapeutically reverse the dyslipidemic profile commonly occurring in hypothyroidism, it should be borne in mind that the potency of the effects may be age-and sex-dependent. Thyroid hormone administration possibly also sustains and enhances the efficacy of hypolipidemic drugs, such as statins, ezetimibe and proprotein convertase subtilisin/kexin type 9 (PCSK9), in patients with dyslipidemia and hypothyroidism.

Hemostasis in Hypothyroidism and Autoimmune Thyroid Disorders

CONTEXT

There are contradictory results on the effect of hypothyroidism on the changes in hemostasis. Inadequate population-based studies limited their clinical implications, mainly on the risk of venous thromboembolism (VTE). This paper reviews the studies on laboratory and population-based findings regarding hemostatic changes and risk of VTE in hypothyroidism and autoimmune thyroid disorders.

EVIDENCE ACQUISITION

A comprehensive literature search was conducted employing MEDLINE database. The following words were used for the search: Hypothyroidism; thyroiditis, autoimmune; blood coagulation factors; blood coagulation tests; hemostasis, blood coagulation disorders; thyroid hormones; myxedema; venous thromboembolism; fibrinolysis, receptors thyroid hormone. The papers that were related to hypothyroidism and autoimmune thyroid disorder and hemostasis are used in this review.

RESULTS

Overt hypothyroidism is more associated with a hypocoagulable state. Decreased platelet count, aggregation and agglutination, von Willebrand factor antigen and activity, several coagulation factors such as factor VIII, IX, XI, VII, and plasminogen activator-1 are detected in overt hypothyrodism. Increased fibrinogen has been detected in subclinical hypothyroidism and autoimmune thyroid disease rendering a tendency towards a hypercoagulability state. Increased factor VII and its activity, and plasminogen activator inhibitor-1 are among several findings contributing to a prothrombotic state in subclinical hypothyroidism.

CONCLUSIONS

Overt hypothyroidism is associated with a hypocoagulable state and subclinical hypothyroidism and autoimmune thyroid disorders may induce a prothrombotic state. However, there are contradictory findings for the abovementioned thyroid disorders. Prospective studies on the risk of VTE in various levels of hypofunctioning of the thyroid and autoimmune thyroid disorders are warranted.

Subclinical hypothyroidism in childhood - current knowledge and open issues

Subclinical hypothyroidism is defined as serum levels of TSH above the upper limit of the reference range, in the presence of normal concentrations of total T₄ or free T₄. This biochemical profile might be an indication of mild hypothyroidism, with a potential increased risk of metabolic abnormalities and cardiovascular disease recorded among adults. Whether subclinical hypothyroidism results in adverse health outcomes among children is a matter of debate and so management of this condition remains challenging. Mild forms of untreated subclinical hypothyroidism do not seem to be associated with impairments in growth, bone health or neurocognitive outcome. However, ongoing scientific investigations have highlighted the presence of subtle proatherogenic abnormalities among children with modest elevations in their TSH levels. Although current findings are insufficient to recommend levothyroxine treatment for all children with mild asymptomatic forms of subclinical hypothyroidism, they highlight the potential need for assessment of cardiovascular risk among children with this condition. Increased understanding of the early metabolic risk factors associated with subclinical hypothyroidism in childhood will help to improve the management of affected individuals.

Effects of L-thyroxine treatment on early markers of atherosclerotic disease in children with subclinical hypothyroidism

OBJECTIVE

To investigate the effect of levothyroxine (L-T4) treatment on early markers of atherosclerotic disease in children with mild idiopathic subclinical hypothyroidism (SH).

DESIGN

Two-year, open, case-control prospective study.

METHODS

A total of 39 children, aged 9.18±3.56 years, with SH and 39 healthy controls were enrolled in the study. Waist-to-height ratio (WHtR), blood pressure, triglycerides, total cholesterol (total-C), HDL-C, LDL-C, non-HDL-C, triglycerides/HDL-C, atherogenic index (AI), homocysteine (Hcy), asymmetric dimethylarginine (ADMA), flow-mediated dilation (FMD) and intima-media thickness (IMT) were evaluated at baseline and after 2 years of L-T4 treatment in SH children and after 2 years of follow-up in controls.

RESULTS

At study entry WHtR was higher in SH subjects compared with controls (0.56±0.08 vs 0.49±0.07, P=0.04) and significantly decreased after 2 years of treatment (0.50±0.06, P<0.0001). Mean HDL-C levels (50.47±11.43 vs 61.06±13.83mg/dL, P=0.002) were lower, while triglycerides/HDL-C (1.63±1.07 vs 1.19±0.69, P=0.05), AI (3.32±0.90 vs 2.78±0.68, P=0.005), and Hcy (9.35±2.61 vs 7.71±1.94μmol/L, P=0.01) were higher in SH subjects compared with controls and improved after 2 years of treatment (HDL-C 56.26±13.76mg/dL, P<0.0001; triglycerides/HDL-C 1.23±0.78, P=0.006; AI 2.82±0.68, P<0.0001; and Hcy 8.25±2.09μmol/L, P=0.06). ADMA concentrations at baseline were higher in SH subjects compared with controls (0.77±0.21 vs 0.60±0.16μmol/L, P=0.001) and decreased after therapy (0.58±0.13μmol/L, P<0.0001). FMD, IMT and other metabolic parameters were not different among SH subjects and controls at baseline and after 2 years.

CONCLUSIONS

Children with SH may have subtle pro-atherogenic abnormalities. Although L-T4 treatment exerts some beneficial effects, the long-term impact of therapy on metabolic outcomes in SH children still remains unclear.

Study on Subclinical Hypothyroidism and its Association with Various Inflammatory Markers

INTRODUCTION

Subclinical hypothyroidism shows the mimic reaction more like to frank hypothyroidism which creates the dilemma. Inflammatory markers can be helpful in assessment of adverse effects of subclinical hypothyroidism, are not very well studied in the past. So the aim of this study was to investigate the role of inflammatory markers in Subclinical hypothyroidism patients.

MATERIALS AND METHODS

The study population consisted of 154 patients with recently diagnosed subclinical hypothyroidism and 100 healthy controls. TSH, FT4 & T3 were estimated by enzyme linked Immunosorbent assay (ELISA) for diagnosis of subclinical hypothyroidism. Total cholesterol, triglycerides, and HDL-C were estimated by spectrophotometric method. LDL - C was calculated by Friedewald formula. Inflammatory markers (ESR, C-reactive protein & Interleukin 6) were also estimated by enzyme linked Immunosorbent assay (ELISA).

RESULTS

In this study the level of TSH Mean ± SD (11.12±4.17 vs 2.73±0.80) and T3 Mean ± SD (0.96±0.17 vs 1.08±0.26) were significantly higher (<0.001) in subclinical hypothyroidism. Serum concentration of FT4 was not significantly different between the groups. Total cholesterol, triglycerides, and LDL-C were significantly higher in patients group. While the level of HDL-C was significantly lower in SCH patients compared to euthyroid group. TSH level was positively correlated with inflammatory markers in subclinical hypothyroidism, which were significantly different in subclinical hypothyroidism.

CONCLUSION

This study suggests that subclinical hypo-thyroidism patients have increased inflammatory markers along with dyslipidemia and due to that future risk of further development of cardiovascular disorder can occur. Level of inflammatory markers increases in patients as disease progress if left untreated.

Hypothyroidism Exacerbates Thrombophilia in Female Rats Fed with a High Fat Diet

Clotting abnormalities are discussed both in the context with thyroid dysfunctions and obesity caused by a high fat diet. This study aimed to investigate the impact of hypo-, or hyperthyroidism on the endogenous thrombin potential (ETP), a master indicator of clotting activation, on Sprague Dawley rats fed a normal or high fat diet. Female Sprague Dawley rats (n = 66) were grouped into normal diet (ND; n = 30) and high-fat diet (HFD; n = 36) groups and subdivided into controls, hypothyroid and hyperthyroid groups, induced through propylthiouracil or triiodothyronine (T3) treatment, respectively. After 12 weeks of treatment ETP, body weight and food intake were analyzed. Successfully induced thyroid dysfunction was shown by T3 levels, both under normal and high fat diet. Thyroid dysfunction was accompanied by changes in calorie intake and body weight. In detail, compared to euthyroid controls, hypothyroid rats showed significantly increased—and hyperthyroid animals significantly decreased—ETP levels. High fat diet potentiated these effects in both directions. In summary, we are the first to show that hypothyroidism and high fat diet potentiate the thrombotic capacity of the clotting system in Sprague Dawley rats. This effect may be relevant for cardiovascular disease where thyroid function is poorly understood as a pathological contributor in the context of clotting activity and obesogenic nutrition.

Atherosclerotic effects of long-term old and new antiepileptic drugs monotherapy: a cross-sectional comparative study

This work aimed to evaluate the metabolic and atherogenic effects of long-term antiepileptic drugs in a group of Egyptian epileptic patients. Sixty-nine epileptic patients on antiepileptic drug monotherapy for at least 2 years and 34 control subjects were recruited in this study. Patients were divided into 5 subgroups according to antiepileptic drugs used (valproate, carbamazepine, lamotrigine, topiramate, and levetiracetam). Fasting lipid profile (total cholesterol, triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol), lipoprotein(a), homocysteine, free thyroxine, thyroid-stimulating hormone, and common carotid artery intima-media thickness were measured for all subjects. Significant higher mean values of low-density lipoprotein cholesterol, low-density lipoprotein / high-density lipoprotein ratio, lipoprotein(a), homocysteine, significantly lower mean value of high-density lipoprotein cholesterol, and significantly larger diameter of common carotid artery intima-media thickness were observed in each drug-treated group versus control group. Our study supports that long-term monotherapy treatment with valproate, carbamazepine, lamotrigine, and topiramate had altered markers of vascular risk that might enhance atherosclerosis, whereas levetiracetam exerted minimal effect.

Low-normal thyroid function and novel cardiometabolic biomarkers

The concept is emerging that low-normal thyroid function, i.e., either higher thyroid-stimulating hormone or lower free thyroxine levels within the euthyroid reference range, could contribute to the development of atherosclerotic cardiovascular disease. It is possible that adverse effects of low-normal thyroid function on cardiovascular outcome may be particularly relevant for specific populations, such as younger people and subjects with high cardiovascular risk. Low-normal thyroid function probably relates to modest increases in plasma total cholesterol, low density lipoprotein cholesterol, triglycerides and insulin resistance, but effects on high density lipoprotein (HDL) cholesterol and non-alcoholic fatty liver disease are inconsistent. Low-normal thyroid function may enhance plasma cholesteryl ester transfer, and contribute to an impaired ability of HDL to inhibit oxidative modification of LDL, reflecting pro-atherogenic alterations in lipoprotein metabolism and HDL function, respectively. Low-normal thyroid function also confers lower levels of bilirubin, a strong natural anti-oxidant. Remarkably, all these effects of low-normal thyroid functional status appear to be more outspoken in the context of chronic hyperglycemia and/or insulin resistance. Collectively, these data support the concept that low-normal thyroid function may adversely affect several processes which conceivably contribute to the pathogenesis of atherosclerotic cardiovascular disease, beyond effects on conventional lipoprotein measures.

Perchlorate Exposure is Associated with Oxidative Stress and Indicators of Serum Iron Homeostasis Among NHANES 2005-2008 Subjects

Perchlorate (ClO4 (-)), an oxidizing agent, is a ubiquitous environmental pollutant. Several studies have investigated its thyroid hormone disrupting properties. Its associations with other biological measures are largely unknown. This study, combining 2005-2008 National Health and Nutrition Examination Surveys, investigated associations between urinary perchlorate and biomarkers of iron homeostasis, lipids, blood cell counts, and glucose metabolism. Healthy males (n = 3705), non-pregnant females (n = 2967), and pregnant females (n = 356), aged 12-59 years, were included in the linear regression models, which showed significant positive (+) and negative (-) associations for both males and non-pregnant females with serum uric acid (-), serum iron (-), RBC count (-), blood urea nitrogen (+), and lymphocyte count (+). Other significant associations were observed for either males or non-pregnant females. Among pregnant females, perchlorate was significantly associated with blood urea nitrogen (+) and serum iron (-). These associations may be indicators of perchlorate's potential effect on several biological systems, which when considered in total, may implicate perturbation of iron homeostasis.

Atherosclerosis in epilepsy: its causes and implications

Evidence from epidemiological, longitudinal, prospective, double-blinded clinical trials as well as case reports documents age-accelerated atherosclerosis with increased carotid artery intima media thickness (CA-IMT) in patients with epilepsy. These findings raise concern regarding their implications for age-accelerated cognitive and behavioral changes in midlife and risk of later age-related cognitive disorders including neurodegenerative processes such as Alzheimer's disease (AD). Chronic epilepsy, cerebral atherosclerosis, and age-related cognitive disorders including AD share many clinical manifestations (e.g. characteristic cognitive deficits), risk factors, and structural and pathological brain abnormalities. These shared risk factors include increased CA-IMT, hyperhomocysteinemia (HHcy), lipid abnormalities, weight gain and obesity, insulin resistance (IR), and high levels of inflammatory and oxidative stresses. The resulting brain structural and pathological abnormalities include decreased volume of the hippocampus, increased cortical thinning of the frontal lobe, ventricular expansion and increased white matter ischemic disease, total brain atrophy, and β-amyloid protein deposition in the brain. The knowledge that age-accelerated atherosclerosis may contribute to age-accelerated cognitive and behavioral abnormalities and structural brain pathologies in patients with chronic epilepsy represents an important research path to pursue future clinical and management considerations.

Different effects of fenofibrate on metabolic and cardiovascular risk factors in mixed dyslipidemic women with normal thyroid function and subclinical hypothyroidism

AIMS

Subclinical hypothyroidism is suggested to increase cardiovascular risk. No previous study compared the effect of any fibrate on plasma levels of lipids and other cardiovascular risk factors in patients with different thyroid function status.

METHODS

The study included three age-, weight- and lipid-matched groups of women with mixed dyslipidemia in different thyroid function status: patients with untreated subclinical hypothyroidism (group 1, n = 18), women with treated hypothyroidism (group 2, n = 15), and subjects without thyroid disorders (group 3, n = 19). Plasma lipids, glucose homeostasis markers, as well as plasma levels of uric acid, high-sensitivity C-reactive protein (hsCRP), homocysteine, and fibrinogen were determined before and after 12 weeks of fenofibrate therapy.

RESULTS

Despite similar plasma lipid levels, mixed dyslipidemic patients with untreated hypothyroidism had decreased insulin sensitivity, as well as higher circulating levels of uric acid, hsCRP, homocysteine, and fibrinogen in comparison with the other groups. The effect of fenofibrate on plasma lipids and, with the exception of homocysteine, on circulating levels of all investigated risk factors was stronger in patients from groups 2 and 3 than in patients from group 1.

CONCLUSIONS

The obtained results indicate that the effect of fenofibrate on plasma lipids and circulating levels of cardiovascular risk factors is partially related to thyroid function. They also suggest that to improve the strength of fibrate action in dyslipidemic patients with subclinical hypothyroidism, they should be administered together with L-thyroxine.

Thyroid hormone regulation of hepatic lipid and carbohydrate metabolism

Thyroid hormone (TH) has important roles in regulating hepatic lipid, cholesterol, and glucose metabolism. Recent findings suggest that clinical conditions such as non-alcoholic fatty liver disease and type 2 diabetes mellitus, which are associated with dysregulated hepatic metabolism, may involve altered intracellular TH action. In addition, TH has key roles in lipophagy in lipid metabolism, mitochondrial quality control, and the regulation of metabolic genes. In this review, we discuss recent findings regarding the functions of TH in hepatic metabolism, the relationship between TH and metabolic disorders, and the potential therapeutic use of thyromimetics to treat metabolic dysfunction in the liver.

Hyperlipidemia and hypothyroidism among metastatic renal cell carcinoma patients taking sunitinib malate. Related or unrelated adverse events?

BACKGROUND

In recent years, new-onset hypothyroidism was extensively reported in patients receiving sunitinib for malignancy. Effects of sunitinib on serum lipids are not described, however a hyperlipidemic state is commonly observed in hypothyroid patients. Here we report about the incidence and severity of hypercholesterolemia and hypertriglyceridemia in a cohort of patients receiving sunitinib for metastatic renal cell carcinoma.

PATIENTS AND METHODS

Thyroid function tests, serum triglycerides, and cholesterol were prospectively evaluated in 39 consecutive metastatic renal cell carcinoma patients, who were receiving sunitinib as a first-line treatment. Incidence of hyperlipidemia, thyroid function impairment, and their possible relationship were investigated.

RESULTS

Thyroid function tests, serum cholesterol, and triglycerides were assessed at baseline and before the beginning of each sunitinib cycle. During treatment, median triglyceride levels increased up to 271.3 mg/dL, and median cholesterol increased up to 234.7 mg/dL (+113% and +22%, respectively). A hyperlipidemic state developed in 27 patients (69.2%) within a mean time of 1.8 six-week cycles (range, 1-5 cycles) and persisted during treatment. Hypothyroidism was observed in 20 patients (51.2%) and usually developed within 2.3 cycles. Because hypothyroidism and hyperlipidemia developed at different time points of treatment and among different patients, our results failed to demonstrate a correlation between these adverse events.

CONCLUSION

New-onset hyperlipidemia was observed in an increased percentage of patients taking sunitinib. The mechanism of this side effect is still unclear. We recommend careful monitoring of serum lipid levels during sunitinib administration to recognize possible consequences, especially on cardiovascular health.

Cardiovascular Risk in Patients with Subclinical Hypothyroidism

Subclinical hypothyroidism (SCH) has been associated with increased cardiovascular mortality due to adverse effects mainly on lipids and blood pressure (BP). There is evidence that SCH, especially in patients with thyroid-stimulating hormone (TSH) >10mU/l, may increase cardiovascular risk. Some uncertainty exists regarding the association of SCH with BP; however, that the coexistence of SCH with BP and hypercholesterolaemia has a negative cardiovascular impact is beyond doubt. Insulin resistance, by modulating various risk factors including coagulation, may potentially increase cardiovascular risk. Periodic health examinations including screening has been advised in patients >35 years of age, while treatment with thyroxine should be tailored to each patient.

Hypothyroidism in clinical practice

Background:

Hypothyroidism is the most common endocrine disease that was seen in the clinical practice especially for family physicians.

Methods:

This review article covered the important practical clinical issues for managing overt hypothyroidism, subclinical hypothyroidism and hypothyroidism during pregnancy.

Conclusions:

The clinical issues were addressed by clinical scenario followed by questions and stressed on the important clinical points.