Lipid abnormalities and cardiometabolic risk in patients with overt and subclinical thyroid disease

Association of the thyroid hormone sensitivity index with triglycerides in adolescents: a cross-sectional study

BACKGROUND

Inconsistent findings have emerged from studies examining the relationship between thyroid hormone sensitivity indices and triglycerides (TGs), especially in pediatric and adolescent cohorts. The present study investigates this relationship within adolescent populations in the United States.

METHODS

Data spanning three periods from 2007 to 2012 were analyzed, including 1813 participants. The thyroid hormone sensitivity index was calculated and weighted multiple linear regression was used to assess the relationships between TG levels and individual thyroid hormone sensitivity indices. Subgroup analyses were conducted as needed and smooth curve fitting plots visualized the linear relationships.

RESULTS

The FT3/FT4 ratio was positively correlated with TG (β = 0.649, 95% CI: 0.360-0.938, P < 0.001). This correlation persisted after adjusting for all variables (β = 0.439, 95% CI: 0.154-0.725, P < 0.01). The relationship between the TFQI score and TG concentration demonstrated a significant negative correlation, which remained after controlling for all covariates (β = -0.153, 95% CI: -0.239-0.067, P < 0.01). When stratified into quartiles, the FT3/FT4 ratio and TG exhibited a positive correlation only in the Q3 and Q4 groups. Conversely, the TFQI was significantly correlated with TG exclusively in the Q4 group's positive values. Stratified analyses by sex and age showed clearer associations in female adolescents.

CONCLUSIONS

The study confirmed the relationship between thyroid hormone sensitivity indices and TGs. Maintaining the FT3/FT4 ratio within a specific range may reduce TG levels. The TFQI may predict TG levels when actual TSH values exceed expected values based on FT4. These findings were most pronounced in female adolescents, highlighting the importance of early monitoring of thyroid health in this group. These results point to the need for improved thyroid function testing in predicting TG levels and preventing hypertriglyceridemia.

A comparative study on serum lipid levels in patients with thyroid dysfunction: a single-center experience in Ethiopia

BACKGROUND

Thyroid diseases are the most common endocrine disorders worldwide. Thyroid hormones are essential for lipid synthesis, metabolism, and mobilization. Lipid levels in the blood may be altered when there is thyroid dysfunction. Lipid changes are linked to hyperthyroidism and primarily involve total and low-density lipoprotein cholesterol. The serum lipid profile is negatively impacted by hypothyroidism, which may increase the risk of atherosclerotic disease development. Thus, hypothyroidism constitutes a significant cause of secondary dyslipidemia. However, the results obtained from different studies are inconsistent, and there are few data regarding lipid profiles in thyroid dysfunction patients in the study area. Therefore, this study aimed to assess the lipid profile of thyroid dysfunction patients at Wolaita Sodo University Comprehensive Specialized Hospital from May 1 to June 15, 2021.

METHODS

A comparative cross-sectional study was conducted involving 200 participants (100 thyroid dysfunction patients and 100 age- and sex-matched controls). Socio-demographic and related data were collected from the study participants via a pretested structured questionnaire through face-to-face interviews. Independent sample T tests and Mann‒Whitney U tests were used for data analysis. P < 0.05 indicated statistical significance.

RESULTS

Out of 200 study participants 40 (20%) hyperthyroid, 60 (30%) hypothyroidism, and 100 (50%) controls. In individuals with hyperthyroidism, the levels of triglycerides, total cholesterol, and low-density lipoprotein cholesterol were significantly lower than those in the control group. Compared to the control group, the hypothyroidism patients had significantly higher levels of triglycerides, low-density lipoprotein cholesterol, total cholesterol, and high-density lipoprotein cholesterol.

CONCLUSION

The lipid profile can change significantly as a result of thyroid dysfunction. Biochemical screening of lipid profiles is essential for improving patients with thyroid dysfunction with dyslipidemia.

Thyroid Stimulatory Activity of Houttuynia cordata Thunb. Ethanolic Extract in 6-Propyl-Thiouracil-Induced Hypothyroid and STZ Induced Diabetes Rats: In Vivo and In Silico Studies

Houttuynia cordata Thunb. holds a longstanding reputation as a traditional folk remedy in East Asia, where it has been employed to treat a variety of inflammatory conditions, nephritis, hepatitis and cancer. Despite its extensive use, there exists a paucity of research examining its efficacy in managing thyroid disorders and diabetes. Moreover, the bioactive components responsible for modulating the molecular pathways remain elusive.

OBJECTIVES

This research aimed to determine the key bioactive components in the ethanolic extract of H. cordata Thunb. (HCEE) responsible for its thyroid-modifying properties and examine its effects on rats with experimentally induced hypothyroidism and diabetes.

METHODS

Molecular docking was performed to investigate the possible mechanisms of thyroid regulation of HCEE constituents. Researchers induced hypothyroidism in rats by adding 6-propyl-2-thiouracil to their drinking water for a period of four weeks. To induce diabetes, the rats received an intraperitoneal injection of streptozotocin. The animals were then given daily oral doses of HCEE (500 mg/kg b.w.), levothyroxine (50 mg/kg b.w.), or glibenclamide (5 mg/kg b.w.) for 28 days. Following this treatment, standard methods were employed to measure biochemical parameters in the rats' serum.

RESULTS

The results demonstrate that HCEE ameliorated hypothyroidism by increasing serum T3 (14.38%) and T4 (125.96%) levels and decreasing TSH (p < 0.01; -41.75%) levels. In diabetic rats with induced hypothyroidism, HCEE significantly (p < 0.001) increased T3 (149.51%) and T4 (73.54%) levels with reduced TSH (-64.39%) levels. In silico analysis demonstrated that the identified bioactive compounds from HCEE may enhance thyroid hormone function through interaction with the thyroid hormone receptor protein TRβ1 (PDB:3GWS), similar to the conventional pharmaceuticals levothyroxine and triiodothyronine (T3).

CONCLUSIONS

HCEE exhibits potential as a natural alternative to synthetic medications in the prevention and treatment of thyroid dysfunctions.

The Effects of Anti-thyroid Drugs on Lipoproteins and Insulin Resistance in Graves' Disease: A Randomized Clinical Trial

Objective

Graves' disease (GD) is characterized by thyroid overactivity. Anti-thyroid drugs (ATDs), such as propylthiouracil (PTU) and methimazole (MMI), are commonly used for GD treatment, and studies have suggested a link between these drugs and elevated lipoprotein levels. However, data on their effects on lipoproteins, insulin resistance, or low-density lipoprotein receptor (LDL-R) levels are lacking, both in Indonesia and in other countries. This study investigated changes in lipoproteins, LDL-R, and insulin resistance markers with ATD treatment.

Methods

This study is a secondary analysis of a randomized clinical trial entitled "The Differential Effects of Propylthiouracil and Methimazole as Graves' Disease Treatment on Vascular Atherosclerosis Markers" conducted in Jakarta, Indonesia. Thirty-seven newly diagnosed GD patients received MMI or PTU for 3 months.

Results

After 3 months of ATD treatment, LDL-R levels significantly decreased compared to baseline (197 vs. 144 ng/mL, p<0.001), while most lipoproteins, including TC, LDL-C, HDL-C, non-HDL-C, the cholesterol ratio, and the LDL-C/HDL-C ratio, increased. Unexpectedly, neither the PTU nor MMI groups showed an increased dyslipidemia prevalence. Although body mass index increased significantly and fasting plasma glucose decreased slightly, no significant post-treatment change in insulin resistance was observed. The study received ethical approval from the Ethics Committee of the Faculty of Medicine, Universitas Indonesia (ref KET-784/UN.2.F1/ETIK/PPM.00.02/2019) and was registered on clinicaltrials.gov (NCT05118542).

Conclusion

ATD treatment for GD led to a significant increase in total cholesterol, LDL-cholesterol, and high-density lipoprotein-cholesterol levels, along with a reduction in LDL-R levels. Both PTU and MMI showed similar effects. These findings provide valuable insights into the effects of ATDs on lipoproteins and insulin resistance in GD patients.

Trial Registration

ClinicalTrials.gov Identifier: NCT05118542.

Conventional HDL Subclass Measurements Mask Thyroid Hormone-dependent Remodeling Activity Sites in Hypothyroid Individuals

Context

Earlier nuclear magnetic resonance spectroscopy (NMR) studies of plasma lipoproteins estimated by size as small, medium, and large particles, demonstrated hypothyroidism was associated with increases in very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and intermediate-density lipoprotein (IDL) subclass particle number but variable changes in the high-density lipoprotein (HDL) subclasses. These disparate changes in HDL might be explained by reduced activity of the thyroid hormone-dependent remodeling proteins whose subclass specificity may be obscured when the 5 HDL subclasses identified by NMR are combined by size.

Objective

This work aimed to determine whether directional changes in particle number of individually measured HDL subclasses correlate with reduced activity of their thyroid hormone-dependent remodeling proteins in hypothyroid individuals.

Methods

VLDL, LDL, IDL, and HDL subclasses were measured by NMR in 13 thyroidectomized individuals 1 month following thyroid hormone withdrawal and 3 months after replacement. Changes in particle numbers in each subclass were compared when expressed individually and by size.

Results

Following thyroid hormone withdrawal, plasma lipids and VLDL, LDL, and IDL subclass particle number increased. HDL particle number nearly doubled in very small HDL-1 (P = .04), declined in small HDL-2 (P = .02), and increased 2-fold in HDL-5 (P = .0009).

Conclusion

The increment in HDL-1 and decline in HDL-2 subclasses is consistent with their precursor-product relationship and reduced lecithin cholesterol acyltransferase activity while the almost 2-fold increase in large HDL-5 is indicative of diminished action of hepatic lipase, phospholipid transfer protein, and endothelial lipase. These findings are inapparent when the 5 subclasses are expressed conventionally by size. This linking of specific HDL subclasses with HDL remodeling protein function provides new details about the specificity of their interactions.

Characteristics and Prevalence of Metabolic Syndrome Among Adult Filipinos with Hypothyroidism: A Cross-sectional Study

Objectives

We determined the clinical characteristics and prevalence of metabolic syndrome among adult Filipinos with overt hypothyroidism.

Methodology

This is a cross-sectional study of 151 adults. Patients were recruited by sequential enrollment. Anthropometric and blood pressure measurements were performed followed by blood extraction for metabolic parameters and thyroid function tests. Clinical and laboratory characteristics were compared between patients with and without metabolic syndrome.

Results

The prevalence of metabolic syndrome is 40.4% (95%CI: 32.5%, 48.7%). Patients with metabolic syndrome have a waist circumference of 88.4 ± 7.7 cm in females and 93.3 ± 9.0 cm in males. The median fasting blood glucose was 111.4 (52.2) mg/dL, median systolic blood pressure of 120 (30) mm Hg and diastolic blood pressure of 80 (20) mmHg, median serum triglycerides of 174.3 (114.2) mg/dL, median HDL-C of 42.3 (19.2) mg/dL and a proportion of patients with diabetes (23.0%) and hypertension (44.3%), respectively. The presence of increased waist circumference is the most prevalent component seen among hypothyroid patients. There were no differences in terms of age, sex, etiology of hypothyroidism and anti-TPO levels in those with and without metabolic syndrome.

Conclusion

The prevalence of metabolic syndrome in adult Filipinos with hypothyroidism is high. Emphasis must be placed on early screening using waist circumference and metabolic parameters among hypothyroid patients who are at high risk of developing metabolic syndrome.

The interference between effects of PFAS exposure on thyroid hormone disorders and cholesterol levels: an NHANES analysis

Studies have documented that per- and polyfluoroalkyl substance (PFAS) exposures are associated with thyroid hormones (TH) and lipid levels. This study investigates whether these effects interfere with each other. We analyzed data on 3954 adults in the US National Health and Nutrition Examination Survey (NHANES; 2007-2012). TH disorder was defined using thyroid hormones. Serum high-density lipoprotein (HDL) cholesterol, total cholesterol, and six types of PFAS were included. Weighted quantile sum (WQS) regression was used to estimate the overall effect of PFAS mixture on TH disorder and cholesterols, respectively. Potential confounders, including age, race, gender, education, household poverty, smoking, and alcohol drinking, were adjusted. PFAS mixture was associated increased risk for TH disorder (odds ratio = 1.21, 95% confidence interval (CI): 1.02, 1.43), higher HDL cholesterol (linear coefficient = 1.31, 95% CI: 0.50, 2.11), and higher total cholesterol (linear coefficient = 5.30, 95% CI: 3.40, 7.21). TH disorder was associated with higher HDL cholesterol (linear coefficient = 2.30, 95% CI: 0.50, 2.11), but not total cholesterol. When adjusted for TH disorder, the effect estimates of PFAS mixture remain roughly unchanged on HDL cholesterol (linear coefficient = 1.13, 95% CI: 0.28, 1.98) and total cholesterol (linear coefficient = 5.61, 95% CI: 3.58, 7.63). Sex modified the effect of PFAS mixture on HDL cholesterol (P for interaction: 0.04) but did not change the interaction between PFAS and TH disorder on cholesterols. We corroborated the adverse health effects of PFAS exposure on TH and lipids; however, these two effects appear to be independent of and not interfere with each other.

The Prevalence of Metabolic Syndrome among Adult Filipinos with Hypothyroidism: A Retrospective Cohort Study

Background and Objectives

Dyslipidemia in hypothyroidism results from the effects of thyroid hormones on lipid metabolism. These, in combination with hypothyroidism-induced hemodynamic changes, are risk factors for cardiometabolic diseases. We determined the prevalence of metabolic syndrome (MS) among adult Filipinos with hypothyroidism and compared clinical and laboratory characteristics of those with versus without MS.

Methods

This is a retrospective study of 105 patients with biochemically confirmed hypothyroidism. A review of records obtained anthropometric measurements, blood pressure, fasting blood glucose, lipid profile, and thyroid hormones. Clinical and laboratory characteristics were then compared between MS and those without. Significant differences were determined by two-way ANOVA, while heterogeneity of categorical variables was determined by chi-square or Fisher exact test. All data analyses were performed using Stata version 17.0 with a significance level of p<0.05.

Results

The prevalence of MS is 36.19% (95%CI: 27.04%,46.15%). Body mass index (BMI) peaks at obese class I among those with MS. There is a significantly higher proportion of patients diagnosed to have diabetes (28.95% vs. 7.46%; p=0.003) and hypertension (52.63% vs. 14.93%; p<0.001) in the MS group. No significant differences were noted between groups regarding age, sex, etiology of hypothyroidism, blood pressure, fasting glucose, lipid profile, and thyroid hormone levels.

Conclusion

Our study showed that the prevalence of MS in adult Filipinos with hypothyroidism is increased at 36.19%. Only BMI, presence of diabetes, and hypertension were shown to be significantly higher. Emphasis must be placed on early screening among hypothyroid patients at high risk of developing MS. A prospective study using waist circumference and clinical and metabolic parameters is needed to validate these findings.

Hepatic Energy Metabolism under the Local Control of the Thyroid Hormone System

The energy homeostasis of the organism is orchestrated by a complex interplay of energy substrate shuttling, breakdown, storage, and distribution. Many of these processes are interconnected via the liver. Thyroid hormones (TH) are well known to provide signals for the regulation of energy homeostasis through direct gene regulation via their nuclear receptors acting as transcription factors. In this comprehensive review, we summarize the effects of nutritional intervention like fasting and diets on the TH system. In parallel, we detail direct effects of TH in liver metabolic pathways with regards to glucose, lipid, and cholesterol metabolism. This overview on hepatic effects of TH provides the basis for understanding the complex regulatory network and its translational potential with regards to currently discussed treatment options of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) involving TH mimetics.

The protective role of nutritional antioxidants against oxidative stress in thyroid disorders

An imbalance between pro-oxidative and antioxidative cellular mechanisms is oxidative stress (OxS) which may be systemic or organ-specific. Although OxS is a consequence of normal body and organ physiology, severely impaired oxidative homeostasis results in DNA hydroxylation, protein denaturation, lipid peroxidation, and apoptosis, ultimately compromising cells' function and viability. The thyroid gland is an organ that exhibits both oxidative and antioxidative processes. In terms of OxS severity, the thyroid gland's response could be physiological (i.e. hormone production and secretion) or pathological (i.e. development of diseases, such as goitre, thyroid cancer, or thyroiditis). Protective nutritional antioxidants may benefit defensive antioxidative systems in resolving pro-oxidative dominance and redox imbalance, preventing or delaying chronic thyroid diseases. This review provides information on nutritional antioxidants and their protective roles against impaired redox homeostasis in various thyroid pathologies. We also review novel findings related to the connection between the thyroid gland and gut microbiome and analyze the effects of probiotics with antioxidant properties on thyroid diseases.

Cancer and Mortality Risks of Graves' Disease in South Korea Based on National Data from 2010 to 2019

Purpose

This study aimed to investigate Graves' disease (GD) associated cancer and mortality risk using a Korean population-based study.

Patients and Methods

We included 6435 patients with GD using the Korean National Health Insurance Service-National Sample Cohort database from 2010 to 2019. Data concerning such patients were compared in a 1:5 ratio with age- and sex-matched non-GD group (n=32,175). Eighteen subdivided types of cancer and cancers-in-total were analyzed. In addition to the mortality analysis, subgroup analyses were performed according to age and sex.

Results

After adjustment, the hazard ratio (HR) of the GD group for cancer-in-total was 1.07 (95% confidence interval [CI], 0.91-1.27), showing no difference when compared to the non-GD group. However, among different types of cancer, the thyroid cancer risk of the GD group was higher than that of the non-GD group (HR=1.70; 95% CI, 1.20-2.39). When subdivided by age and sex, the thyroid cancer risk of the GD group in males aged 20-39 years was higher than that of the non-GD group (HR=7.00; 95% CI, 1.48-33.12). The mortality risk of the GD group was not different from that of the non-GD group (HR=0.86; 95% CI, 0.70-1.05).

Conclusion

In South Korea, patients with GD had a higher risk of thyroid cancer than the non-GD group. In particular, males aged 20-39 years with GD were more likely to have thyroid cancer than the non-GD group.

Efficacy evaluation of probiotics combined with prebiotics in patients with clinical hypothyroidism complicated with small intestinal bacterial overgrowth during the second trimester of pregnancy

Objective

To explore the effect of probiotics combined with prebiotics on clinical hypothyroidism during pregnancy combined with small intestinal bacterial overgrowth.

Methods

(1) In total, 441 pregnant women were included in this study. A total of 231 patients with clinical hypothyroidism during the second trimester of pregnancy and 210 normal pregnant women were enrolled in the lactulose methane-hydrogen breath test. The positive rate of intestinal bacterial overgrowth (SIBO), gastrointestinal symptoms, thyroid function and inflammatory factors were compared between the two groups by chi-square test and two independent sample t-test. (2) SIBO-positive patients in the clinical hypothyroidism group during pregnancy (n=112) were treated with probiotics combined with prebiotics based on conventional levothyroxine sodium tablets treatment. The changes in the methane-hydrogen breath test, gastrointestinal symptoms, thyroid function and inflammatory factors were compared before treatment (G0) and 21 days after treatment (G21) by chi-square test and paired sample t test.

Results

(1) The positive rates of SIBO in pregnant women in the clinical hypothyroidism group and control group were 48.5% and 24.8%, respectively. (2) The incidence of abdominal distention and constipation in the clinical hypothyroidism group was significantly higher than that in the control group, and the risk of abdominal distention and constipation in SIBO-positive pregnant women was higher than that in SIBO-negative pregnant women. (3) The serum levels of hypersensitive C-reactive protein (hsCRP), IL-10, IL-6, TNF-α, low-density lipoprotein (LDL), total cholesterol (TC), free fatty acids (FFAs) and apolipoprotein B (ApoB) in the hypothyroidism group during pregnancy were higher than those in the control group. (4) After 21 days of probiotics combined with prebiotics, the incidence of pure methane positivity in the methane-hydrogen breath test in the G21 group was significantly reduced, and the average abundance of hydrogen and methane at each time point in the G21 group was lower than that in the G0 group. (5) The incidence of constipation in the G21 group was significantly lower than before treatment. (6) The levels of serum TSH, hsCRP, IL-6, TNF-α, TC and LDL in pregnant women after probiotics combined with prebiotics were lower than those before treatment.

Conclusion

Probiotics combined with prebiotics are effective in the treatment of pregnant patients with clinical hypothyroidism complicated with SIBO, providing a new idea to treat pregnant patients with clinical hypothyroidism complicated with SIBO.

Serum Prooxidant-Antioxidant Balance and hs-CRP in Patients with Clinical and Subclinical Hypothyroidism

Background

Oxidative stress (OS) is caused by an imbalance between prooxidant substance production and antioxidant defense. OS is involved in physiologic interactions in the body and the pathogenesis of various disorders. This study aimed to evaluate serum prooxidant-antioxidant balance (PAB) as a selective prooxidant, antioxidant defense, and acute phase reactant protein in patients with subclinical and clinical hypothyroidism.

Methods

This case-control study was conducted in three groups including clinical hypothyroidism (32 patients), subclinical hypothyroidism, (42 cases), and healthy controls (32 individuals). This study was performed in the Endocrine Clinic of Arash Training and Research Hospital, Tehran, 2017. In the study groups, thyroid hormones including T4 and Thyroid Stimulating Hormone (TSH), fasting blood glucose (FBG), lipid profile, PAB, and hs-CRP as inflammatory markers were measured and compared between the groups.

Results

Among 106 participants, 95.3% were females, the gender balance was similar across groups and mean age was 30.79 ± 7.65 years. FBG and lipid profile except for cholesterol level were not significantly different between the three study groups. However, cholesterol level in the clinical hypothyroid group was significantly higher than the other two groups. PAB was higher in subclinical hypothyroidism compared to healthy controls after adjustment for age and TSH levels (P value: 0.04) but there was no significant difference in the clinical hypothyroid group in comparison with healthy controls. In addition, there was no significant difference in high-sensitivity C-reactive protein (hs-CRP) between the three study groups.

Conclusions

This study suggests that that subclinical hypothyroidism increases PAB in comparison to healthy control which could indicate OS response in patients with subclinical hypothyroidism, respectively.

The relationship between thyroid hormones and lipid profile in subclinical hypothyroidism female patients

Background and objectives: Subclinical thyroid disorder is a most common subclinical disease among many medical conditions such as cardiovascular disease and subclinical Lyme disease. The aim of this study was to determine the relationship between lipid profile results, lipid ratios, and anthropometric parameters and thyroid hormones. Methods: One hundred patients (ages 20 to 50 years) with subclinical hypothyroidism (SHT group) and 50 healthy subjects (control group), who are age-matched with patients, were included in the current study. Thyroid function tests (TSH, T3 and T4) were determined by immunodiagnostic assay system (VIDAS) for all participants. The serum glucose and lipid profile tests parameters were evaluated by Biolis 24i Premium chemistry analyser. In addition, systolic and diastolic blood pressure were measured for each individual in the study using mercury sphygmomanometer. Results: The levels of high-density lipoprotein-cholesterol (HDL-c) were significantly lower in the SHT group when compared with control group. Whereas, the level of low-density lipoprotein-cholesterol (LDL-c), the ratios total cholesterol (TC)/HDL-c and LDL-c/HDL-c were significantly higher in SHT group than in controls. Moreover, TSH was negatively correlated with diastolic blood pressure. Conclusions: Both LDL-c and HDL-c are altered in subclinical hypothyroidism patients. And, there is a negative association between TSH and diastolic blood pressure.

Dyslipidemia in South African patients with hypothyroidism

Background

Overt hypothyroidism leads to increased cardiovascular risk, primarily through effects the disorder has on lipids. Most studies investigating lipids in the setting of hypothyroidism, have been performed in predominantly Caucasians in North America and Europe. Different patterns and prevalence of dyslipidemia have been described; one study reporting dyslipidemia in 90% of patients with hypothyroidism. The prevalence of dyslipidemia in overt hypothyroidism among the ethnically diverse predominantly black South African population is unknown.

Methodology

A retrospective case-control study evaluating lipid profiles of an ethnically diverse cohort of patients with overt hypothyroidism (TSH > 10 mIU/L) attending two academic hospitals in Johannesburg, South Africa from September 2006-September 2016. Patients with primary or secondary causes for dyslipidemia and those taking lipid-lowering therapy were excluded.

Results

Two hundred and six patients with hypothyroidism were included and compared to 412 euthyroid controls matched for sex, ethnicity, and age. Most hypothyroid patients were female (n = 180;67.5 %). Median TSH was similar across all ethnic groups (p = 0.09). Median TC, TG and LDL-C were higher in hypothyroid patients (p < 0.01). Normal lipid profiles were found in 29.44 % of all hypothyroid patients. However, a greater proportion, 47 of 124 (37.90 %), black African patients with hypothyroidism had a normal lipid profile.

Conclusion

Dyslipidemia is less common in black African patients with hypothyroidism. This is probably due to this population group being in an earlier stage of epidemiologic transition. Those with hypothyroidism were at greater overall cardiovascular risk based on TC/HDL-C ratio but did not reach high risk atherogenic profiles reported in previous studies.

The Effects of Zinc and Selenium Supplementation on Body Composition and Thyroid Function in Individuals with Overweight or Obesity: A Systematic Review

People with obesity have been found to have lower zinc (Zn) and selenium (Se) circulatory levels and abnormal thyroid function than people with normal weight. Studies about the effects of Zn and Se supplementation on body composition and thyroid function of overweight-obese people showed inconsistent results. A systematic review of randomized controlled trials was conducted to determine the effects of Ζn supplementation, Se supplementation, and their combination on body composition and thyroid function of individuals with overweight or obesity. Databases of PubMed, ScienceDirect, and Cochrane, were searched from inception to February 27, 2022, to identify relevant articles. For the assessment of the methodological quality of the studies, the Jadad scale was used. After screening the articles, thirteen studies were finally included and were analyzed using the strength of the evidence approach. Regarding the effectiveness of Zn supplementation on body composition, moderate evidence was found, while the effects of Se were found to be mixed. Zn supplementation was found to affect the thyroid function of people with overweight or obesity by increasing their free triiodothyronine (FT3) levels. However, this result is based only on one study among hypothyroid patients. At this point, the effectiveness of Zn, Se, and their combination, on the body composition and the thyroid function of people with overweight or obesity cannot safely be determined because of the controversial results, small number, and the limitations of the identified studies. The results of this systematic review must be interpreted with caution due to the limitations detected.

The Relationship of Circulating Proprotein Convertase Subtilisin/Kexin Type 9 With TSH and Lipid Profile in Newly Diagnosed Patients With Subclinical and Overt Hypothyroidism

Introduction:

Overt and subclinical hypothyroidism are mostly associated with dyslipidemia, an essential cardiovascular risk factor. Recently, thyroid stimulating hormone (TSH) was identified to have a direct role on lipid metabolism via increased expression of hepatic proprotein convertase subtilisin/kexin type 9 (PCSK9). PCSK9 plays a crucial role in lipid metabolism via regulating LDL-C levels. Thus, we aimed to evaluate circulating PCSK9 levels and to assess its relationship with serum TSH and lipids in newly diagnosed patients had overt and subclinical hypothyroidism.

Methods:

In our study, we enrolled 60 newly diagnosed untreated patients with overt and subclinical hypothyroidism and 30 euthyroid subjects served as the control group. Serum TSH, FT4, FT3, lipid profile and circulating PCSK9 levels using ELISA kits were measured in all subjects. Our data were summarized using mean ± SD or median and interquartile range. Correlations between PCSK9 expression levels and different variables were done using Spearman correlation coefficient.

Results:

Circulating PCSK9 median levels were significantly increased in patients had overt and subclinical hypothyroidism (12.45 ng/ml, 7.50 ng/ml respectively) compared to the control group (3.30 ng/ml) (P < .001). Circulating PCSK9 levels significantly correlated positively with TSH, total cholesterol, triglycerides, and BMI, and negatively correlated with FT4 and FT3 among all studied subjects. Using multivariate regression analysis TSH was the only significant independent predictor of circulating PCSK9 (P < .001).

Conclusion:

Our results supports the new implication of TSH in lipid metabolism via the significant association with PCSK9. Whether this relationship between TSH and PCSK9 is a cause or just an association needs further evaluation.

Essentiality, relevance, and efficacy of adjuvant/combinational therapy in the management of thyroid dysfunctions

Thyroid dysfunction is the most prevalent endocrine disorder worldwide having an epidemiology of 11% in Indians, 4.6% in the United Kingdom, and 2% in the United States of America among the overall population. The common thyroid disorders include hypothyroidism, hyperthyroidism, Hashimoto's thyroiditis, and thyroid cancer. This review briefly elaborates the molecular regulation and mechanism of thyroid hormone, and its associated thyroid disorders. The thyroid hormones regulate critical biochemical functions in brain development and function. Hypothyroidism is mainly associated with dysregulation of cytokines, increased ROS production, and altered signal transduction in major regions of the brain. In addition, it is associated with reduced antioxidant capacity and increased oxidative stress in humans. Though 70% of thyroid disorders are caused by heredity, environmental factors have a significant influence in developing autoimmune thyroid disorders in people who are predisposed to them. This drives us to understand the relationship between environmental factors and thyroid dysregulated disorders. The treatment option for the thyroid disorder includes antithyroid medications, receiving radioactive iodine therapy, or surgery at a critical stage. However, antithyroid drugs are not typically used long-term in thyroid disease due to the high recurrence rate. Adjuvant treatment of antioxidants can produce better outcomes with anti-thyroid drug treatment. Thus, Adjuvant therapy has been proven as an effective strategy for managing thyroid dysfunction, herbal remedies can be used to treat thyroid dysfunction in the future, which in turn can reduce the prevalence of thyroid disorders.

Metabolic Changes after Radioiodine Correction of Grade 1 and Grade 2 Subclinical Hyperthyroidism

OBJECTIVE

Endogenous subclinical hyperthyroidism (eSCH) is defined by subnormal serum thyroid-stimulating hormone (TSH) level. There is limited evidence of metabolic changes induced by eSCH. The aim of our work was to evaluate changes in BMI and lipid parameters after radioiodine treatment in patients with grade 1 (TSH: 0.1-0.39 mlU/L) and 2 (TSH <0.1 mlU/L) eSCH.

DESIGN

A retrospective study was performed on 74 patients with eSCH caused by benign autonomous nodular goiter which was treated with radioiodine.

METHODS

We assessed BMI, lipids parameters, and TSH after radioiodine therapy. The 12-month follow-up time point was used to compare the primary outcome variables. TSH was measured by the electrochemiluminescence method.

RESULTS

After radioiodine therapy, the absolute and relative increases in BMI at 12 months were significantly higher in the grade 2 group than in the grade 1 group (1.07 ± 0.27 kg/m² vs. 0.26 ± 0.15 kg/m², respectively; p = 0.023 and 4.01 ± 0.98% vs. 1.01 ± 0.56%, respectively; p = 0.026). Compared to baseline, significant increases in the levels of total cholesterol and LDL were observed after treatment in the grade 2 eSCH group (16.7 ± 4.5 mg/dL p < 0.01 and 14.3 ± 4.1 mg/dL p < 0.01, respectively) but not in the grade 1 group. In a multivariate model, a negative correlation was observed between pretreatment TSH levels and absolute BMI gain (p < 0.01).

CONCLUSIONS

After correction of eSCH, increases in BMI and LDL levels were observed only in patients with grade 2 eSCH. Pretreatment serum TSH was the main independent factor associated with BMI changes after radioiodine treatment.

Association of lipoproteins and thyroid hormones with cognitive dysfunction in patients with systemic lupus erythematosus

Background

Neuropsychiatric manifestations occur in up to 75% of adult systemic lupus erythematosus (SLE) patients and are one of the major causes of death in SLE patients. Cognitive dysfunction is a typical clinical feature of neuropsychiatric SLE (NPSLE), which seriously affects the quality of life of patients. Dyslipidaemia and thyroid symptoms, which are prevalent in SLE patients, have both been related to neuropsychiatric disturbances, including significant psychiatric and cognitive disturbances. This study aimed to investigate whether cognitive dysfunction in patients with SLE was related to the expression of serum thyroid hormone and lipoprotein levels.

Methods

A total of 121 patients with SLE and 65 healthy controls (HCs) at Nanjing Drum Tower Hospital completed a cognitive function test, and 81 SLE patients were divided into a high-cognition (n = 33) group and a low-cognition group (n = 48). The clinical and laboratory characteristics of the patients were compared; moreover, correlations between serum HDL-C, LDL-C, F-T3 and F-T4 levels and cognitive function were analysed. Serum levels of APOE, APOA1, IGF-1, and IGFBP7 in 81 patients were detected by ELISA, and the correlation between these four proteins and cognition was analysed separately.

Results

The patients with SLE with abnormal cognitive function were less educated than the HCs. For low-cognition patients, the levels of albumin, F-T3 (P <  0.05) and F-T4 decreased, while D-dimer, anti-dsDNA antibody, and IgM levels increased. Serum F-T3 and F-T4 levels positively correlated with cognition. Furthermore, serum protein levels of APOE and APOA1 showed no difference between the high- and low-cognition groups. However, the serum APOE levels were negatively correlated with line orientation scores, and APOA1 levels were positively correlated with coding scores.

Conclusions

Serum F-T3 and F-T4 levels were both positively correlated with four indexes of cognition (language was the exception), while serum APOE levels were negatively correlated with line orientation scores, APOA1 levels were positively correlated with coding scores, and IGFBP7 levels were negatively correlated with figure copy scores. These results demonstrated that F-T3 and F-T4 might be clinical biomarkers of cognitive dysfunction in SLE.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41927-021-00190-7.

Lipidomic Perturbations in Cynomolgus Monkeys are Regulated by Thyroid Stimulating Hormone

Thyroid disease affects an estimated 200 million people worldwide, and is commonly associated with increased blood lipid levels. However, the mechanism by which thyroid-stimulating hormone (TSH) affects lipid profiles is not clear. Twenty-four cynomolgus monkeys were treated with a novel exogenous recombinant human TSH (rhTSH) (SNA001) at 9 μg kg⁻¹, 22 μg kg⁻¹, or 54 μg kg⁻¹, and reference rhTSH (Thyrogen^®) at 22 μg kg⁻¹. The primary TSH (SNA001) pharmacokinetic (PK) parameters increased in a dose-dependent manner across the dose range of 9 μg kg⁻¹, 22 μg kg⁻¹, or 54 μg kg⁻¹. Peak triiodothyronine (T3) and thyroxine (T4) levels were reached within 24 h after rhTSH administration, which was delayed by approximately 20 h. In total, 420 lipid species were detected and quantified by ultra-performance liquid chromatography high resolution spectrometry (UPLC-HR-MS)-based lipidomics. Notably, peak levels of lipid accumulation, particularly sphingomyelin (SM) and triglycerides (TG), appeared at 4 and 24 h, which was consistent with the pattern of TSH and T3/T4 levels, respectively. According to weighted correlation network analysis (WGCNA), perturbations of many lipid species were strongly correlated with TSH and T3/T4 levels. TSH and the stimulated T3/T4 levels and lipid profiles following SNA001 administration were comparable to those after administration of the reference rhTSH (Thyrogen^®). The plasma lipidome and changes in lipid levels after rhTSH stimulation were associated with TSH and T3/T4 concentrations. T3/T4 and lipid profiles were delayed after TSH stimulation. Such phenomena require further exploration.

Sensitivity to Thyroid Hormone Indices Are Closely Associated With NAFLD

BACKGROUND

Previous studies on the association between thyroid function and non-alcoholic fatty liver disease (NAFLD) have contradicted. Acquired resistance to thyroid hormone theory might provide a reasonable explanation for these contradictions. We aimed to analyze the association between sensitivity to thyroid hormone indices with NAFLD.

METHODS

A total of 4,610 individuals from the health medical center of the First Hospital of China Medical University were included in this study. The previously used thyroid feedback quantile-based index (TFQI_FT4) was calculated. Also, we substituted free triiodothyronine (FT₃) into the TFQI formulas to get the TFQI_FT3 index. NAFLD was defined using abdominal ultrasound.

RESULTS

Study results showed that FT₃/FT₄ and TFQI_FT3 were positively correlated with the triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels (P<0.05) and negatively correlated with high-density lipoprotein cholesterol (HDL-C) level (P<0.05). In contrast, TFQI_FT4 was positively correlated with HDL-C level (P < 0.05). After adjustment for multiple confounders, FT₃, FT₃/FT₄, and TFQI_FT3 were positively associated with the risks of dyslipidemia and NAFLD (P < 0.05). TFQI_FT3 and FT₃/FT₄ performed better than TFQI_FT4 on ROC analyses for NAFLD prediction, although the diagnostic sensitivity and specificity at the optimal cut-points were low. However, no association was observed between TFQI_FT4 with the risks of dyslipidemia and NAFLD.

CONCLUSION

TFQI_FT3 and FT₃/FT₄ can be used as new indicators for predicting dyslipidemia and NAFLD, although with low sensitivity and specificity at the optimal cut-points, while TFQI_FT4 has insufficient evidence in predicting dyslipidemia and NAFLD.

The current debate over treatment of subclinical hypothyroidism to prevent cardiovascular complications

BACKGROUND

Subclinical hypothyroidism (SCH) is an asymptomatic condition associated with increased thyroid-stimulating hormone (TSH) >4 mIU/L with normal thyroxine (T4) and triidothyronine (T3) levels. It is more common in older subjects and especially in women with an overall incidence of 10%.

OBJECTIVE

Because the normal TSH levels increase with age up to 7.5 mIU/L in older people, several studies have reported either no benefits whereas others have reported the benefits of treatment. These studies have caused a great debate over the treatment of SCH, especially in older subjects. Therefore, the objective of this study was to review the current evidence over this debate by reviewing the recent literature on the subject to discern whether treatment of SCH is necessary and under what circumstances.

METHODS

To get a better perspective on the current debate over treatment of SCH, a focused Medline search of the English language literature was conducted from 2012 to 2019 using the terms, hypothyroidism, subclinical, dyslipidaemia, cardiovascular disease, heart failure and 38 papers with pertinent information were selected.

RESULTS

The analysis of results from these papers indicated that the normal levels of TSH are increasing with the advancement of age from 4 mIU/L up to 7.5 mIU/L for patients ≥75 years of age. Also, several of reviewed studies have shown no benefits of treatment whereas, others have shown definite benefits of treatment with levothyroxine supplementation on the clinical and metabolic effects of SBH with reductions in CVD, HF and mortality. The treatment is more effective in younger persons and less so in older persons.

CONCLUSIONS

Based on the overall evidence, treatment of SCH is indicated in younger persons with a TSH level >4.0 mIU/L. In older subjects, treatment should be individualised and based on the presence of symptoms, the level of TSH, and initiated at TSH levels ≥10 mIU/L and at low doses to avoid adverse cardiovascular effects from overtreatment.

Untreated adult GH deficiency is not associated with the development of metabolic risk factors: a long-term observational study

PURPOSE

Uncertainties exist about the predictors of the severity of the clinical picture of GH deficiency (GHD) syndrome. Aim of the study was to evaluate, in adult patients with GHD, the predictors of the development of hypercholesterolemia, hypertension, diabetes mellitus, and osteoporosis.

METHODS

We retrospectively studied 327 adult patients (age 47.1 ± 17.1 years) with untreated severe GHD (mean follow-up 110.9 ± 56.8 months). GHD was defined by GHRH + arginine test using BMI cut-offs. The possible development of hypercholesterolemia, hypertension, diabetes mellitus, and osteoporosis was investigated by Kaplan-Meier survival analysis. For each clinical outcome, either a univariate or multivariate analysis according to the Cox proportional-hazards model was performed to identify those factors that were associated with the development of the event.

RESULTS

GH secretion parameters were not associated with the outcomes. Hypercholesterolemia was positively and negatively predicted by a BMI ≥ 30 kg/m² (HR 2.50, p 0.00) and the dose of l-thyroxine possibly in place (HR 0.98, p 0.02), respectively. Hypertension was positively predicted by a BMI ≥ 30 kg/m² (HR 2.64, p 0.00) and IGF-I SDS values (HR 2.26, p 0.00). Diabetes mellitus was positively predicted by hypertension (HR 11.76, p 0.01). Osteoporosis was positively and negatively predicted by hypercholesterolemia (HR 3.25, p 0.01) and hypertension (HR 0.21, p 0.00), respectively.

CONCLUSIONS

The severity of the impairment of GH secretion does not predict the development of the clinical picture of GHD syndrome: untreated adult GHD does not increase the development of metabolic risk factors in hypopituitaric patients.

Oxidative stress enhances the immune response to oxidatively modified catalase enzyme in patients with Graves' disease

BACKGROUND

Oxidative stress is associated with several autoimmune disorders and oxidative modification of proteins that may result in autoimmune response. This study aims to evaluate the catalase (CAT) activity and the autoimmune response against the native CAT and the oxidatively modified enzyme in patients with Graves' disease (GD) and healthy controls in a comparative way.

METHODS

The CAT activity was evaluated via spectrophotometric method. Using enzyme-linked immunosorbent assay, the reactivities of autoantibody toward native, malondialdehyde (MDA) and hydrogen peroxide (H2 O2 ) modified CAT were evaluated in plasmas of patients and controls.

RESULTS

Reduced CAT activity was found in patients compared with controls (P < .05). It was proved that levels of IgG antibodies against MDA-modified CAT were higher than against unmodified ones (P < .001). No changes were found for the reactivities to H2 O2 -modified CAT. Positive correlation was found between the reactivity to MDA-modified CAT and the triiodothyronine level (P < .001, r = .6).

CONCLUSION

Our findings incriminate the MDA in the autoantibodies reactivity to oxidatively modified CAT leading to a disturbed oxidative profile and/or the progression of GD pathology.

Subclinical Hyperthyroidism: Status of the Cholesterol Transfers to HDL and Other Parameters Related to Lipoprotein Metabolism in Patients Submitted to Thyroidectomy for Thyroid Cancer

Purpose: Lipid metabolism has been poorly explored in subclinical hyperthyroidism. The aim was to examine the effects of exogenous subclinical hyperthyroidism in women under levothyroxine treatment upon plasma lipids and aspects of HDL metabolism. Methodology: Ten women were studied in euthyroidism and again in exogenous subclinical hyperthyroidism. Thyroid function tests and plasma lipids were studied. Results: HDL-cholesterol (increased 21.6%, p = 0.0004), unesterified cholesterol (increased 12.3%, p = 0.04) and Lp(a) (increased 33,3%, P = 0.02) plasma concentrations were higher in subclinical hyperthyroidism compared to euthyroidism, but total cholesterol, LDL, non-HDL cholesterol, triglycerides, apo A-I, apo B were unchanged. PON1 activity (decreased 75%, p = 0.0006) was lower in subclinical hyperthyroidism. There were no changes in HDL particle size, CETP and LCAT concentrations. The in vitro assay that estimates the lipid transfers to HDL showed that esterified cholesterol (increased 7.1%, p = 0.03), unesterified cholesterol (increased 7.8%, p = 0.02) and triglycerides (increased 6.8%, p = 0.006) transfers were higher in subclinical hyperthyroidism. There were no changes in phospholipid transfers to HDL in subclinical hyperthyroidism. Conclusions: Several alterations in the plasma lipid metabolism were observed in the subclinical hyperthyroidism state that highlight the importance of this aspect in the follow-up of those patients. The increase in HDL-C and in the transfer of unesterified and esterified cholesterol to HDL, an important anti-atherogenic HDL function are consistently protective for cardiovascular health. The increase in Lp(a) and the decrease in PON-1 activity that are important risk factors were documented here in subclinical hyperthyroidism and these results should be confirmed in larger studies due to great data variation but should not be neglected in the follow-up of those patients.

The role of fish oil in attenuating cardiac oxidative stress, inflammation and fibrosis in rat model of thyrotoxicosis

Hyperthyroidism is associated with cardiovascular complications. Fish oil reduces risk of cardiovascular diseases. This study aims to evaluate the impact of fish oil on myocardial oxidative stress, inflammation and fibrosis in rat model of thyrotoxicosis. Rats were randomized into four groups; control rats, fish oil treated rats (FO, 100mg omega-3/100g body weight/day), hyperthyroid rats (Hyper, i.p levothyroxine 3 mg/kg/day), and hyperthyroid rats treated with fish oil (Hyper + FO) for 8 weeks. Changes in oxidants/antioxidants, inflammatory and fibrotic markers were measured. Thyrotoxicosis increased serum endothelin-1, thiobarbituric acid reactive substances (TBARS) and reduced activities of cardiac catalase and super oxide dismutase (SOD). Cardiac fibrosis paralleled with a decrease of matrix metalloproteinase -2 (MMP2) levels were observed in Hyper group. Use of FO increased activities of SOD and catalase, increased TBARS levels, and attenuated cardiac fibrosis by normalizing MMP-2 levels. Use of FO may attenuate cardiac oxidative stress and fibrosis in hyperthyroid states.

Prevalence and Risk Factors of Thyroid Dysfunction in Older Adults in the Community

Prevalence estimates and evidence informing treatment targets for thyroid dysfunction largely come from studies of middle-aged adults. We conducted a cross-sectional analysis to determine the prevalence of thyroid dysfunction and risk factors for abnormal thyroid tests in participants aged ≥65 in the Atherosclerosis Risk in Communities (ARIC) study (N = 5,392). We measured serum concentrations of triiodothyronine (T3), free thyroxine (FT4), thyroid peroxidase antibody (Anti-TPO), and thyroid stimulating hormone (TSH). In this population (58% women, 22% black), 17% reported medication use for thyroid dysfunction. Among those not on treatment, the prevalence of overt and subclinical hypothyroidism was 0.82% and 6.06%, respectively. Overt and subclinical hyperthyroidism affected 0.26% and 0.78%, respectively. Multivariable adjusted TSH, FT4 and T3 levels were 25%, 1.3% and 3.9% lower in blacks compared to whites, respectively. Men were less likely to be anti-TPO positive compared to women (p < 0.001). Former and never smoking were associated with lower T3 and FT4 levels compared to current smoking. The prevalence of thyroid dysfunction in older adults is nearly 25%. Multiple illnesses can interact to contribute to declines in health. Additional attention to thyroid dysfunction and screening in this age group is recommended.

Effectiveness of early identification and electronic interventions for teens with risk factors for the development of heart disease and diabetes: Phase II findings

BACKGROUND AND PURPOSE

Serum and physical risk factors for the development of heart disease and diabetes are detectable long before adulthood. The purpose of this two-part study was to assess the prevalence and associations of these risk factors in teens and determine the effectiveness of a customizable two-part electronic education program on minimizing identified risks.

METHODS

Data were collected from teens (n = 168) from two high schools (one urban and one rural) in the mid-Atlantic region. After baseline data were collected, the two-part electronic education program was initiated. Serum and physical risk factors were rechecked at 12-week intervals, and results were analyzed.

CONCLUSIONS

Significant serum and physical risk factor associations were identified and remained present among teens over the course of the study. High-density lipoproteins showed significant, steady improvement. Low-density lipoproteins were positively associated with body mass index, diastolic blood pressure, and thyroid-stimulating hormone level.

IMPLICATIONS FOR PRACTICE

Although serum and physical risk factors are identifiable in teens, routine screening of this age group and younger is not an established standard of care. Health care providers need effective, innovative methods to counteract these risks. Through increased awareness of the presence of risk factors in young patients, advanced nurse practitioners may implement earlier interventions to counteract these risks.

Acquired low cholesterol: diagnosis and relevance to safety of low LDL therapeutic targets

PURPOSE OF REVIEW

Acquired hypocholesterolaemia occurs more commonly than inherited hypocholesterolaemia but has received little attention in the literature. In this review, we discuss the causes and underlying mechanisms of acquired hypocholesterolaemia and its relevance to safety of therapeutically induced decreased LDL cholesterol levels.

RECENT FINDINGS

Hypocholesterolaemia is increasingly identified as cholesterol testing becomes more widespread in the assessment of cardiovascular risk. Lower therapeutic targets for LDL cholesterol are also being achieved more regularly with the introduction of more intensive cholesterol-lowering regimens. Acquired hypocholesterolaemia may be the presenting feature of treatable diseases. Understanding its mechanisms may also provide new treatment approaches for neoplastic disease, such as breast cancer, and infections, such as tuberculosis.

SUMMARY

When hypocholesterolaemia is discovered, it is important to identify its cause. Further research into the pathogenesis of hypocholesterolaemia may provide new therapies for primary diseases underlying it.

Homeostatic Model Assessment-Insulin Resistance (HOMA-IR 2) in Mild Subclinical Hypothyroid Subjects

Despite various studies with conflicting results, the effect of thyroid hormones on lipids and insulin levels in dysthyroidism is of great interest. This case control study was aimed to perceive the existence of IR and dyslipidemia in mild subclinical hypothyroid subjects (TSH ≤ 9.9 µIU/ml) as compared to their age and gender matched euthyroid controls. Basic demographic information like height, weight was recorded. Serum samples of all the subjects were assayed for thyroid profile, lipid profile, blood glucose, HbA1C and insulin. BMI and insulin resistance was calculated. Compared to controls patients with mild subclinical hypothyroidism demonstrated hyperinsulinemia and dyslipidemia observed by the higher LDL cholesterol. A significantly positive correlation was observed for HOMA-IR with TSH and LDL cholesterol. Hence, even in the mild subclinical hypothyroid state assessment of thyroid function should be combined with estimation of plasma glucose, insulin and serum lipids to monitor and prevent its associated effects.

Serum Lipid Transfer Proteins in Hypothyreotic Patients Are Inversely Correlated with Thyroid-Stimulating Hormone (TSH) Levels

Background

Plasma cholesteryl ester transfer protein (CETP) activity is often decreased in patients with hypothyroidism, whereas less is known about the phospholipid transfer protein (PLTP). We aimed to evaluate simultaneously serum CETP and PLTP activity in patients diagnosed with hypothyroidism.

Material/Methods

The selection criteria for control group members (without thyroid dysfunction) in this case to case study were levels of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), and triglycerides similar to those in study group patients (101 patients diagnosed with hypothyroidism). Serum CETP and PLTP activities were measured by homogenous fluorometric assays using synthetic donor particle substrates.

Results

Serum CETP and PLTP activities in hypothyreotic patients were lower (p<0.001) compared with those in healthy subjects. This lowering was associated with significant changes in HDL-C subclasses: decrease in HDL₂- and increase in HDL₃ cholesterol levels. Multiple linear regression analyses adjusted for age, sex, body mass index, smoking habits, and alcohol drinking showed a strong association between hypothyroidism and activity of lipid transfer proteins. A linear inverse relationship between thyroid-stimulating hormone (TSH) and CETP (r=−0.21; p<0.01) and between TSH and PLTP (r=−0.24; p<0.001) was shown. There also was a positive correlation (p<0.001) between CETP and HDL₂ cholesterol (r=0.27) and between PLTP and HDL₂ cholesterol (r=0.37). A negative correlation between CETP and HDL₃ cholesterol (r=−0.22: p<0.01) and between PLTP and HDL₃ cholesterol (r=−0.24; p<0.001) has been demonstrated as well.

Conclusions

The decreased HDL₂ and increased HDL₃ cholesterol levels in subjects with hypothyroidism are consequences of decreased activity of lipid transfer proteins. These changes are early symptoms of lipid disturbances in hypothyroidism.

Effects of thyroid hormone withdrawal on metabolic and cardiovascular parameters during radioactive iodine therapy in differentiated thyroid cancer

Objective To investigate the cardiometabolic effects of a severe hypothyroid state induced by withdrawal of thyroid hormone replacement before radioactive iodine therapy. Methods Patients with thyroid cancer who were scheduled to receive radioactive iodine ablation were enrolled. Cardiometabolic parameters were measured using blood samples taken immediately before levothyroxine withdrawal, 4 weeks following withdrawal (on radiotherapy day), and 4 weeks following reinstitution of levothyroxine. Results Out of 48 patients (age 49.4 ± 10.5 years; 77.1% [37/48] female), the severe hypothyroid state induced by levothyroxine withdrawal significantly aggravated the majority of lipid parameters, particularly in patients with a greater number of metabolic syndrome components. Fasting plasma glucose levels and homeostatic model assessment values for insulin resistance and β-cell function significantly decreased following levothyroxine withdrawal. Serum high-sensitivity C-reactive protein, fibrinogen and cystatin C levels significantly decreased, and homocysteine levels increased during the severe hypothyroid state. All of these changes were reversed by levothyroxine reinstitution. Conclusions Severe hypothyroid state induced pronounced changes in cardiometabolic parameters. Further studies should identify the long-term effects of changes in these parameters on cardiovascular morbidity and mortality in relation to thyroid disease.

The effect of L-thyroxine replacement therapy on ischemia-modified albümin and malondialdehyde levels in patients with overt and subclinical hypothyroidism

BACKGROUND AND OBJECTIVES

The main objective of this study was to evaluate the levels of ischemia-modified albumin (IMA) and malondialdehyde (MDA) in patients with subclinical (SHypo) and overt hypothyroidism (OHypo), and to assess the effects of levothyroxine (LT₄) therapy on the oxidative stress (OS) parameters. We also investigated the relationships among serum thyroid hormones, lipid parameters, and IMA and MDA in these patients.

DESIGN AND METHODS

Thirty untreated patients with OHypo, 25 untreated patients with Shypo, and 30 age- and sex-matched healthy controls were prospectively included in the study. Biochemical and hormonal parameters including IMA and MDA were evaluated in all patients just before and one month after the maintenance of euthyroidism.

RESULTS

Compared with the control subjects, the levels of MDA and triglycerides (TG) significantly increased in patients with SHypo (p < 0.001 and p < 0.05, respectively), whereas high density lipoprotein cholesterol (HDL-C) levels significantly decreased (p = 0.01). Patients with OHypo showed significantly high MDA, total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), and TG levels (p = 0.001, p < 0.01, p = 0.01, and p < 0.01, respectively), and significantly low HDL-C levels compared with the controls (p < 0.05). MDA levels and lipid profile were not significantly different in the patients with OHypo when compared with the patients with SHypo. Serum IMA levels did not significantly change in patients with OHypo and SHypo compared with the controls. In the pre-treatment period, MDA levels were inversely correlated with HDL-C levels in patients with OHypo (r: -0.471, p = 0.009). Plasma MDA and LDL-C levels significantly decreased and HDL-C levels significantly increased in the groups of OHypo and SHypo after LT₄ treatment. Serum IMA levels did not significantly change with the therapy in all patient groups.

CONCLUSIONS

Increased MDA levels in both patient groups represent increased lipid peroxidation which might play an important role in the pathogenesis of the atherosclerosis seen in these patients. Increased OS in patients with SHypo and OHypo could be improved by LT₄ treatment. Also, MDA can be used as a reliable marker of OS and oxidative damage, while IMA is considered to be inappropriate.

A rabbit model of fatal hypothyroidism mimicking "myxedema coma" established by microscopic total thyroidectomy

Myxedema coma (MC) is a life-threatening endocrine crisis caused by severe hypothyroidism. However, validated diagnostic criteria and treatment guidelines for MC have not been established owing to its rarity. Therefore, a valid animal model is required to investigate the pathologic and therapeutic aspects of MC. The aim of the present study was to establish an animal model of MC induced by total thyroidectomy. We utilized 14 male New Zealand White rabbits anesthetized via intramuscular ketamine and xylazine administration. A total of 7 rabbits were completely thyroidectomized under a surgical microscope (thyroidectomized group) and the remainder underwent sham operations (control group). The animals in both groups were monitored without thyroid hormone replacement for 15 weeks. Pulse rate, blood pressure, body temperature, and electrocardiograms (ECG) were recorded and blood samples were taken from the jugular vein immediately prior to the thyroidectomy and 2 and 4 weeks after surgery. The thyroidectomized rabbits showed a marked reduction of serum thyroxine levels at 4 weeks after the surgical procedure vs. controls (0.50±0.10 vs. 3.32±0.68 μg/dL, p<0.001). Additionally, thyroidectomized rabbits exhibited several signs of hypothyroidism such as hypothermia, systolic hypotension, bradycardia, and low voltage on ECGs, compared with controls. Of the 7 rabbits with severe hypothyroidism, 6 died from 4 to 14 weeks after the thyroidectomy possibly owing to heart failure, because histopathologic examinations revealed a myxedema heart. In summary, we have established a rabbit model of fatal hypothyroidism mimicking MC, which may facilitate pathophysiological and molecular investigations of MC and evaluations of new therapeutic interventions.

Association Between Thyroid Hormones, Lipids and Oxidative Stress Markers in Subclinical Hypothyroidism

BACKGROUND

Oxidative stress plays a role in the pathogenesis of many chronic diseases. It is recognized in overt hypothyroidism while its existence in subclinical hypothyroidism (SCH) is not well established. The aim of this study was to determine whether there was increased oxidation of lipids and proteins in SCH, and examine their association with lipids and thyroid hormones.

METHODS

Male adults (35-59 years) with SCH (n=467) and euthyroid controls (n=190) were studied. Anthropometric measurements, plasma lipids, thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), total antioxidant capacity (T-AOC), lipid peroxidation products, malondialdehyde (MDA), advanced oxidation protein products (AOPP) and dityrosine concentrations were measured.

RESULTS

Plasma concentrations of MDA were significantly higher (p<0.05) in SCH (8.11±1.39 nmol/mL) compared with euthyroid controls (7.34±1.31 nmol/mL) while AOPP, dityrosine and T-AOC levels were not different. MDA was not associated with TSH (β=-0.019, P=0.759), FT4 (β=-0.062, P=0.323) and FT3 (β=-0.018, P=0.780) in SCH while levels increased with elevated total cholesterol (β=0.229, P=0.001), LDL (β=0.203, P=0.009) and triglycerides (β=0.159, P=0.036) after adjustment for age and body mass index. T-AOC reduced (β=-0.327, P=0.030) with increased MDA in euthyroid controls and not in SCH (β=-0.068, P=0.349), while levels increased with elevated triglycerides in both groups.

CONCLUSIONS

Oxidative stress was increased in subclinical hypothyroidism as evidenced by the elevated lipid peroxidation product, malondialdehyde, while protein oxidation was absent. Thus, reduction of oxidative stress may be beneficial in patients with subclinical hypothyroidism.

Oxidized LDL Is Strictly Limited to Hyperthyroidism Irrespective of Fat Feeding in Female Sprague Dawley Rats

Metabolic dysfunctions might play a crucial role in the pathophysiology of thyroid dysfunctions. This study aimed to investigate the impact of a controlled diet (normal versus high fat feeding) on hypothyroid and hyperthyroid Sprague Dawley rats. Female Sprague Dawley rats (n = 66) were grouped into normal diet (n = 30) and high-fat diet (n = 36) groups and subdivided into controls, hypothyroid and hyperthyroid groups, induced through propylthiouracil or triiodothyronine (T3) treatment, respectively. After 12 weeks of treatment metabolic parameters, such as oxidized LDL (oxLDL), malondialdehyde (MDA), 4-hydroxynonenal (HNE), the lipid profile, body weight and food intake parameters were analyzed. Successfully induced thyroid dysfunctions were shown by T3 levels, both under normal and high fat diet. Thyroid dysfunctions were accompanied by changes in calorie intake and body weight as well as in the lipid profile. In detail, hypothyroid rats showed significantly decreased oxLDL levels, whereas hyperthyroid rats showed significantly increased oxLDL levels. These effects were seen under high fat diet and were less pronounced with normal feeding. Taken together, we showed for the first time in female SD rats that only hyper-, but not hypothyroidism, is associated with high atherogenic oxidized LDL irrespective of normal or high-fat diet in Sprague Dawley rats.

AICAR-Induced Activation of AMPK Inhibits TSH/SREBP-2/HMGCR Pathway in Liver

Our previous study found that thyroid-stimulating hormone promoted sterol regulatory element-binding protein-2 (SREBP-2) expression and suppressed AMP-activated protein kinase (AMPK) activity in the liver, but it was unclear whether there was a direct link between TSH, AMPK and SREBP-2. Here, we demonstrate that the 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR)-induced activation of AMPK directly inhibited the expression of SREBP-2 and its target genes HMGCR and HMGCS, which are key enzymes in cholesterol biosynthesis, and suppressed the TSH-stimulated up-regulation of SREBP-2 in HepG2 cells; similar results were obtained in TSH receptor knockout mice. Furthermore, AMPK, an evolutionally conserved serine/threonine kinase, phosphorylated threonine residues in the precursor and nuclear forms of SREBP-2, and TSH interacted with AMPK to influence SREBP-2 phosphorylation. These findings may represent a molecular mechanism by which AMPK ameliorates the hepatic steatosis and hypercholesterolemia associated with high TSH levels in patients with subclinical hypothyroidism (SCH).

Proprotein convertase subtilisin/kexin type 9 (PCSK9), soluble lectin-like oxidized LDL receptor 1 (sLOX-1) and ankle brachial index in patients with differentiated thyroid cancer

The cardiovascular effects of short-term overt hypothyroidism are not well known. We investigated proprotein convertase subtilisin/kexin type 9 (PCSK9), soluble lectin-like oxidized LDL receptor 1 (sLOX-1) and the ankle brachial index (ABI) in thyroid cancer patients with short-term overt hypothyroidism due to thyroid hormone withdrawal (THW). Twenty-one patients requiring radioactive iodine (RAI) ablation or scanning and 36 healthy control subjects were enrolled. Patients were evaluated in the subclinical thyrotoxic phase when they were on suppressive levothyroxine therapy and in the overt hypothyroid phase due to THW for four weeks. PCSK9, sLOX-1, lipids and ABI were measured in the patient and control groups. Total cholesterol, LDL cholesterol, triglycerides and Apo B levels were increased in short overt hypothyroidism compared with the control group (p<0.001). PCSK9 levels increased before THW and after THW in the patients compared to control group (p<0.001, p=0.004, respectively). sLOX-1 levels were not different between patients with short term overt hypothyroidism and control group (p=0.27). ABI was found to be significantly decreased in patients with thyroid cancer before and after THW compared to control group (p=0.04, p=0.002 respectively). PCSK9 levels were correlated negatively with ABI (r=-0.38, p=0.004). In conclusion; our study demonstrated that patients with differentiated thyroid cancer both before and after THW which is a short term overt hypothyroid phase, had increased PCSK9 levels and decreased ABI. Short term overt hypothyroidism also leads to increased HDL, LDL, total cholesterol, Apo A and Apo B levels.

Ischemia-modified albümin and malondialdehyde levels in patients with overt and subclinical hyperthyroidism: effects of treatment on oxidative stress

The main purpose of this study was to evaluate the levels of ischemia-modified albumin (IMA) and malondialdehyde (MDA) in patients with OHyper and SHyper, to assess the effects of antithyroid drug (ATD) therapy on the oxidative stress (OS) parameters. Forty-five untreated patients with overt hyperthyroidism (OHyper), 20 untreated patients with subclinical hyperthyroidism (SHyper) and 30 age-and sex-matched healthy controls were prospectively included in the study. Biochemical and hormonal parameters were evaluated in all patients before and after treatment. Compared with the control subjects, the levels of MDA, glucose and TG were significantly increased in patients with SHyper (p<0.05), whereas LDL-C levels were significantly decreased (p<0.01). Patients with OHyper showed significantly elevated MDA and glucose levels (p<0.001) and significantly decreased LDL-C and HDL-C levels compared with the controls (p<0.01). In patients with Graves' disease, serum TSH levels were inversely correlated with plasma MDA levels (r: -0.42, p<0.05). Plasma MDA levels significantly decreased and levels of TC, LDL-C and HDL-C significantly increased in the groups of OHyper and SHyper after treatment. Serum IMA levels did not significantly change at baseline and with the therapy in all subjects. In conclusion, increased MDA levels in both patient groups represent increased lipid peroxidation which might play an important role in the pathogenesis of the atherosclerosis in these patients. Increased oxidative stress in patients with SHyper and OHyper could be improved by ATD therapy. Also, MDA can be used as a reliable marker of OS and oxidative damage, while IMA is considered to be inappropriate.

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.

Effect of Diabetes Mellitus and Its Control on Myocardial Contractile Function in Rats

AIM: This work was done to study the effect of both types of diabetes mellitus (DM) on myocardial contractility in rats. Also, we investigated the role of treatment of DM with insulin and rosiglitazone (used as treatment for type 1 and type 2 DM respectively) in improvement of myocardial dysfunction in diabetic rats.METHODS: The study included 50 male Wistar albino rats, divided into 5 groups: control (group I), streptozotocin induced type 1 DM (group II), fructose induced type 2 DM (group III), insulin treated type 1 diabetic rats (group IV) and rosiglitazone treated type 2 diabetic rats (group V). At the end of the study, retro-orbital blood samples were withdrawn and blood glucose, plasma triglyceride (TG), total cholesterol (TC) and thyroid hormones levels were measured. Rats were then anesthetized and their hearts were excised and connected to Langendorff apparatus to perform mechanical cardiac performance tests including heart rate (HR), left ventricular developed pressure (LVDP) and maximum rate of pressure rise (+dp/dt).RESULTS: Data of the study showed that relative to control group, there was significant increase in blood glucose, plasma TG and TC levels while, thyroid hormones and myocardial performance parameters showed significant decrease in both type 1 and type 2 diabetic rats. Treatment of type 1 diabetic rats with insulin and type 2 with rosiglitazone resulted in significant decrease in blood glucose, plasma TG and TC levels associated with significant improvement in thyroid hormones and myocardial performance parameters. The results also showed that insulin treatment of type 1 was more effective in ameliorating all parameters than treatment of type 2 by rosiglitazone.CONCLUSION: We concluded that the induction of both types of diabetes resulted in decreased myocardial performance parameters. The  treatment of type 1 and type 2 diabetes by insulin and oral rosiglitazone respectively improved to a great extent the altered metabolism and  mechanical myocardial parameters, with more improving effect of  insulin in type 1 than rosiglitazone in type 2 DM.

The effect of iron supplement on children with euthyroid goiter: a randomized placebo-controlled clinical trial

BACKGROUND

Endemic goiter is present in most parts of Iran. Iron deficiency adversely affects the physiology of thyroid. The initial steps of thyroid hormone synthesis are catalyzed by thyroperoxidases and are dependent on iron. In many developing countries, children are at high risk of both goiter and iron deficiency anemia. In addition, iron deficiency may alter central nervous system control of thyroid metabolism; andalso Iron-deficiency anemia decreases plasma concentrations of thyroxine and triiodothyronine.

MATERIAL AND METHOD

We conducted a randomized, double-blind,controlled trial in 2-12-y-old children with euthyroid goiter and without iron-deficiency anemia. THE CHILDREN WEREDIVIDED INTO TWO GROUPS: The Patients who were under treatment with ferrous-sulphat and controls .active treatment consisted of iron supplementation was administered orally with a dose of 2 mg/kg day. The duration of active treatment was 12 weeks.

RESULTS

In this study 40 children (female: 22, male: 18) were divided into two groups randomly. (20 patients in each group).There were no significant differences at baselines between groups with regard to gender, age and weigh. At the end of the study, the reduction of more than one grade of goiter was significant between iron-treated and placebo groups. In treatment group, 16 patients (80%) had decreased grade of goiter, while in the control group, 3 patients (15%) had grade reduction(P-value<0.001).

CONCLUSION

At the end of the study, decrease of more than one grade of goiter had significant differences between iron-treated and control groups.

The relationships between thyroid hormones and thyroid-stimulating hormone with lipid profile in euthyroid men

BACKGROUND AND AIM

Alteration in lipid profile is a common observation in patients with thyroid dysfunction, but the current knowledge on the relationship between lipids and thyroid hormone levels in euthyroid state is insufficient. The current study aimed to determine the association between thyroid hormones and thyroid-stimulating hormone (TSH) with lipid profile in a euthyroid male population.

METHODS

A total of 708 Chinese and Malay men aged 20 years and above were recruited in this cross-sectional study. Their blood was collected for the determination of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), triglyceride (TG), free thyroxine (FT4), free triiodothyronine (FT3) and TSH levels. The association was analyzed using multiple regression and logistic regression models with adjustment for age, ethnicity, body mass index and FT4/FT3/TSH levels.

RESULTS

In multiple regression models, TSH was positively and significantly associated with TG (p<0.05). Free T4 was positively and significantly associated with TC, LDL-C and HDL-C (p<0.05). Free T3 was negatively and significantly associated with HDL-C (p<0.05). In binary logistic models, an increase in TSH was significantly associated with higher prevalence of elevated TG in the subjects (p<0.05), while an increase in FT4 was significantly associated with higher prevalence of elevated TC but a lower prevalence of subnormal HDL in the subjects (p<0.05). Free T3 was not associated with any lipid variables in the logistic regression (p>0.05).

CONCLUSIONS

In euthyroid Malaysian men, there are positive and significant relationships between TSH level and TG level, and between FT4 level and cholesterol levels.

Daily versus alternate day thyroxine therapy to maintain euthyroidism in children with congenital hypothyroidism

BACKGROUND

Daily administration of thyroxine has proven efficacy in treatment of children with hypothyroidism. However, the possibility of treatment with longer dosing intervals that offers flexibility and choice in maintaining euthyroid state has not been tested in children.

OBJECTIVES

To study the efficacy of an alternate day regimen to maintain euthyroidism in children with congenital hypothyroidism.

PATIENTS AND METHODS

Forty patients given alternate day therapy, while 30 children continued on their daily regimen were followed up at monthly intervals for 3 months. Clinical and laboratory assessments were performed at each follow up visit.

RESULTS

The clinical and anthropometric parameters remained similar in both groups of patients during the study indicating a maintained euthyroid state clinically. The thyroid profiles also remained within normal limits suggesting biochemical euthyroidism status with alternate day therapy. However the baseline serum aminotransferase levels showed mild elevation in patients on alternate day regimen and the difference persisted during the follow up visits. Higher HDL and lower TC and LDL levels suggested some beneficial effect of alternate day schedule on lipid profiles.

CONCLUSIONS

In short-term, alternate day schedule can be effectively used to maintain clinical and biochemical euthyroid state in children with congenital hypothyroidism beyond 4 years of age.