Establishment of a prediction model of pulmonary artery hypertension in patients with hyperthyroidism.

OBJECTIVE: This study aims to assess the tricuspid annular plane systolic excursion (TAPSE)/PASP ratio as a potential indicator for predicting the probability of developing pulmonary arterial hypertension (PAH) in hyperthyroidism patients. A nomogram model will be developed based on our findings, as well as the receiver operating characteristic (ROC) curve. METHODS: The study involved 166 hyperthyroid patients treated at Yijishan Hospital, and the period covered August 2021 to August 2022. Patients were divided into two groups according to pulmonary artery systolic pressure ≥35 mmHg. Univariate and multivariate logistic analyses were performed on the two groups' demographic and laboratory data to identify potential diagnostic markers. These parameters were evaluated using ROC curves to determine their precision in forecasting PAH. The findings were validated by plotting a calibration curve based on a line chart model. RESULTS: In the study, eventually, 80 patients were enrolled: 30 in the PAH group and 50 in the No PAH group. Multipleistic regression analysis predicted the occurrence risk of developing PAH. When paired with other conventional echocardiographic parameters (such as TAPSE, MPI, and SV) and serological markers (such as FT3 and FT4), the developed model demonstrated outstanding predictive performance with an area under the ROC curve of 0.985, a Youden index of 0.971, a sensitivity of 100%, and a specificity of 97.1%. CONCLUSIONS: The nomogram model constructed by combining the TAPSE/PASP ratio with FT3 and FT4 serum markers, as well as conventional ultrasound parameters SV and MPI in hyperthyroidism patients, demonstrates robust discriminatory ability and consistency.

Comparison of pathophysiology in subclinical hyperthyroidism with different etiologies.

Subclinical hyperthyroidism (SHyper) is defined as normal levels of free thyroxine (fT4) and free triiodothyronine (fT3) with suppressed levels of TSH. Previous studies have reported the individual pathophysiology of endogenous SHyper patients and athyreotic patients receiving TSH suppression therapy with levothyroxine; however, apparently no studies have compared the two conditions. Five-hundred-forty untreated endogenous SHyper patients and 1,024 patients receiving TSH suppression therapy who underwent total thyroidectomy for papillary thyroid carcinoma were sampled. Thyroid hormone profiles and peripheral indices related to thyrotoxicosis were investigated in endogenous SHyper patients, athyreotic patients receiving TSH suppression therapy, and healthy participants. Endogenous SHyper patients showed significantly higher thyroid hormone levels (fT4 [p < 0.001] and fT3 [p < 0.001]), and peripheral indices showed a significant tendency towards thyrotoxicosis (strong TSH suppression: alkaline phosphatase [ALP, p < 0.001], creatinine [Cre, p < 0.001], pulse rate [p < 0.05]; and mild TSH suppression: Cre [p < 0.05]) than healthy participants. In contrast, athyreotic patients receiving TSH suppression therapy showed a significant tendency towards thyrotoxicosis than healthy participants only when TSH was strongly suppressed (fT3 [p < 0.001] and Cre [p < 0.001]). Endogenous SHyper patients showed significantly higher fT3 levels (p < 0.001) than athyreotic patients receiving TSH suppression therapy; however, there was a significant tendency towards thyrotoxicosis only when TSH was strongly suppressed (ALP [p < 0.05] and pulse rate [p < 0.05]). The effects of endogenous SHyper and TSH suppression therapy on target organ function are different. Although the serum thyroid hormone profile is similar to that of the thyrotoxic state, athyreotic patients receiving TSH suppression therapy with mildly suppressed serum TSH levels are not thyrotoxic.

Myxedema in Both Hyperthyroidism and Hypothyroidism: A Hormetic Response?

Myxedema is a potentially life-threatening condition typically observed in severe hypothyroidism. However, localized or diffuse myxedema is also observed in hyperthyroidism. The exact cause and mechanism of this paradoxical situation is not clear. We report here the analysis of body fluid distribution by bioelectrical impedance analysis (BIA) in 103 thyroid patients, subdivided according to their functional status. All BIA parameters measured in subclinical thyroid dysfunctions did not significantly differ from those observed in euthyroid controls. On the contrary, they were clearly altered in the two extreme, opposite conditions of thyroid dysfunctions, namely overt hyperthyroidism and severe hypothyroidism, indicating the occurrence of a typical hormetic condition. Surprisingly, differences in BIA parameters related to fluid body composition were even more evident in hyperthyroidism than in hypothyroidism. A hormetic response to thyroid hormone (TH)s was previously reported to explain the paradoxical, biphasic, time- and dose-dependent effects on other conditions. Our results indicate that myxedema, observed in both hypothyroid and hyperthyroid conditions, represents another example of a hormetic-type response to THs. BIA offers no additional valuable information in evaluating fluid body composition in subclinical thyroid dysfunctions, but it represents a valuable method to analyze and monitor body fluid composition and distribution in overt and severe thyroid dysfunctions.

Effects of Chronic Suppression or Oversuppression of Thyroid-Stimulating Hormone on Psychological Symptoms and Sleep Quality in Patients with Differentiated Thyroid Cancer.

In differentiated thyroid cancer (DTC), the standard treatment includes total thyroidectomy and lifetime levothyroxine (LT4) replacement. However, long-term exogenous LT4 has become controversial due to the adverse effects of oversuppression. The study included 191 patients (aged 18-76 years) with a prospective diagnosis of non-metastatic DTC and 79 healthy individuals. The patients with DTC were stratified into three groups according to their TSH levels: suppressed thyrotropin if TSH was below 0.1 µIU/ml, mildly suppressed thyrotropin if TSH was between 0.11 and 0.49 µIU/ml, and low-normal thyrotropin if THS was between 0.5 and 2 µIU/ml. The Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Anxiety Sensitivity Index (ASI), Short Symptom Inventory (SSI), and Pittsburgh Sleep Quality Index (PSQI) were administered to all participants. It was found that the BDI, BAI, SSI and PSQI scores were worse in patients with DTC (p=0.024, p=0.014, p=0.012, and p=0.001, respectively). According to theTSH levels, the mean ASI was found to be higher in the suppressed and mildly suppressed thyrotropin groups (19±14.4 vs. 10.6±11.1; 16.4±14.9 vs. 10.6±11.1, p=0.024, respectively), the mean SSI was found higher in the suppressed group (61.0±55.5 vs. 35.1±37.0, p=0.046), and the mean PSQI was higher in all three groups (7.94±3.97 vs. 5.35±4.13; 7.21±4.59 vs. 5.35±4.13; 7.13±4.62 vs. 5.35±4.13, p=0.006) when compared with the controls. No significant difference was found between the groups. A positive correlation was detected in the duration of LT4 use and BDI and SSI, and a weak, negative correlation was detected between TSH levels and ASI and PSQI. Based on our study, it was found that depression, anxiety disorders, and sleep problems were more prevalent in patients with DTC, being more prominent in the suppressed TSH group. These results were inversely correlated with TSH values and positively correlated with the duration of LT4 use. Unnecessary LT4 oversuppression should be avoided in patients with DTC.

Current approach to surgical management of hyperthyroidism.

Hyperthyroidism is a set of disorders that involve excess synthesis and secretion of thyroid hormones by the thyroid gland, which leads to thyrotoxicosis. The most common forms of hyperthyroidism include diffuse toxic goiter (Graves' disease), toxic multinodular goiter (Plummer disease), and a solitary toxic adenoma. The most reliable screening measure of thyroid function is the thyroid-stimulating hormone (TSH) level. Options for treatment of hyperthyroidism include: antithyroid drugs, radioactive iodine therapy (the preferred treatment of hyperthyroidism among US thyroid specialists), or thyroidectomy. Massive thyroid enlargement with compressive symptoms, a suspicious nodule, Graves' orbitopathy, and patient preference are indications for surgical treatment of thyrotoxicosis. This paper reviews the current literature and controversies on the surgical approach to the management of hyperthyroidism.

Risk of perioperative thyroid storm in hyperthyroid patients: a systematic review.

BACKGROUND: Thyroid storm is a feared complication in patients with hyperthyroidism undergoing surgery. We assessed the risk of thyroid storm for different preoperative treatment options for patients with primary hyperthyroidism undergoing surgery. METHODS: Pubmed, EMBASE, and The Cochrane Library were searched systematically for all studies reporting on adult hyperthyroid patients undergoing elective surgery under general anaesthesia. Selected studies were categorised based on preoperative treatment: no treatment, antithyroid medication (thionamides), iodine, ß-blocking medication, or a combination thereof. Treatment effect, that is restoring euthyroidism, was extracted from the publications if available. Risk of bias was assessed using the Risk of Bias in Non-randomised Studies of Interventions (ROBINS-I) or the Cochrane Risk of Bias tool for randomised studies. RESULTS: The search yielded 7009 articles, of which 26 studies published between 1975 and 2020 were selected for critical appraisal. All studies had moderate to critical risk of bias, mainly attributable to risk of confounding, classification of intervention status, and definition of the outcome. All studies reported on thyroidectomy patients. We found no randomised studies comparing the risk of thyroid storm between treated and untreated patients. Cases of thyroid storm were reported in all treatment groups with incidences described ranging from 0% to 14%. CONCLUSION: Evidence assessing the risk of perioperative thyroid storm is of insufficient quality. Given the seriousness of this complication and the impossibility of identifying patients at increased risk, preoperative treatment of these patients remains warranted.

Prevalence, predictors and outcomes of thyroid dysfunction in patients with acute myocardial infarction: the ThyrAMI-1 study.

PURPOSE: Thyroid dysfunction in patients with cardiac disease is associated with worse outcomes. This study aimed to evaluate the prevalence and analyse predictors and outcomes of thyroid dysfunction in patients presenting with an acute myocardial infarction (AMI). METHODS: A prospective multicentre observational study of patients recruited from six acute hospitals within the North of England. Consecutive patients without previous thyroid disease presenting with both ST-elevation AMI (STEMI) and non-ST-elevation AMI (NSTEMI) were recruited to the Thyroxine in Acute Myocardial Infarction 1 (ThyrAMI-1) cohort study between December 2014 and 2016. Thyroid profile, standard biochemistry measurements and demographic information were obtained within 12 h of admission to hospital. Multivariable logistic regression analyses were performed to assess the predictors of thyroid dysfunction and Cox proportional hazards analyses were utilised to compare all-cause mortality by categories of thyroid dysfunction up to June 2019. RESULTS: Of the 1802 participants analysed, 1440 (79.9%) were euthyroid, 312 (17.3%) had subclinical hypothyroidism (SCH), 22 (1.2%) had subclinical hyperthyroidism (SHyper) and 25 (1.3%) had low T3 syndrome (LT3S). Predictors for SCH were increasing age, female sex, higher thyroid peroxidase antibody (TPOAb) levels, higher serum creatinine levels and early morning sampling time (between 00:01-06:00 h). The predictors of SHyper were lower body mass index and afternoon sampling time (between 12:01 and 18:00 h). Predictors of LT3S were increasing age, higher creatinine levels and presence of previous ischaemic heart disease. Compared to the euthyroid group, patients with LT3S had higher all-cause mortality; adjusted hazard ratio (95% CI) of 2.02 (1.03-3.95), p = 0.04, whereas those with SCH and SHyper did not exhibit significantly increased mortality; adjusted hazard ratios (95% CI) of 1.05 (0.74-1.49), p = 0.79 and 0.27 (0.04-1.95), p = 0.19, respectively. CONCLUSIONS: Thyroid dysfunction is common in AMI patients on admission to hospital and our data provide an understanding regarding which factors might influence thyroid dysfunction in these patients. Furthermore, the negative association between LT3S and increased mortality post-AMI has once again been highlighted by this study. More research is required to assess if treatment of thyroid dysfunction improves clinical outcomes.

Erythroderma (exfoliative dermatitis). Part 2: energy homeostasis and dietetic management strategies.

Erythroderma (exfoliative dermatitis) is associated with important metabolic changes that include an enhancement in energy expenditure. The key components to total energy expenditure (TEE) include basal metabolic rate (~68% of TEE), physical activity (~22% of TEE) and thermic effect of food (~10% of TEE). In the erythrodermic state, there are likely multiple contributors to the increase in basal metabolic rate, such as 'caloric drain' resulting from increased evaporation of water from enhanced transepidermal water loss, increased activity of the cardiovascular system (including high-output cardiac failure), increased nonshivering thermogenesis and hormonal changes such as hypercortisolaemia. A change in the patient's level of physical activity and appetite as a result of ill health status may further impact on their TEE and energy consumption. In Part 2 of this two-part concise review, we explore the key constituents of energy homeostasis and the potential mechanisms influencing energy homeostasis in erythroderma, and suggest much-needed dietetic management strategies for this important condition.

Altered attention networks in patients with thyroid dysfunction: A neuropsychological study.

Patients with thyroid dysfunction (31 hypothyroid, 32 subclinical hypothyroidism, 34 hyperthyroid, and 30 subclinical hyperthyroidism) and 37 euthyroid control subjects were recruited and performed the attention network test (ANT), which can simultaneously examine the alertness, orientation and execution control of the participants. Patients with hypothyroidism had abnormalities in the alerting network, and those with hyperthyroidism had impairments of the alerting and executive control networks. No attention networks deficit existed in patients with subclinical hyperthyroidism and subclinical hypothyroidism. The anxiety and depression scores of patients with thyroid dysfunction were significantly higher than those of the healthy control group. Covariance analysis demonstrated that interactions between group and Hamilton Anxiety Scale scores, group and HAMD score were not significant, but there was a significant main effect for group when analyzing the difference in values of the alerting network between groups. Further, the efficiency of the executive control network was negatively correlated with the T4 level in the hypothyroidism group, and positively correlated with the T4 level in the hyperthyroidism group. T4 or T3 level and efficiencies of the executive control network had a significant quadratic U-shaped relationship in all participants. In summary, the patients with four kinds of thyroid dysfunction exhibited different characteristics of ANT performance. Patients with thyroid dysfunction had various degrees of anxiety and depression disorders, but anxiety and depression disorders had no effect on the differences in the executive control network between the groups.

Thyrotoxic periodic paralysis: A retrospective, observational study from India.

Background & objectives: Thyrotoxic periodic paralysis (TPP) is an endocrine emergency presenting with acute-onset flaccid paralysis in a patient having thyrotoxicosis accompanied by hypokalaemia. This study was conducted to evaluate the clinical profile of patients with TPP presenting to three centres in India. Methods: This retrospective, observational study was conducted at three tertiary care Armed Forces medical centres, located at Lucknow, Kolkata and Delhi. The history, clinical features, treatment details and outcomes were evaluated. Results: Of the 244 patients with thyrotoxicosis, 15 were diagnosed with TPP and included in the study. These 15 patients (14 male and 1 female) had 32 episodes of TPP which were analyzed. The mean age was 30.2±6.2 yr (range: 21-39), and overt thyrotoxicosis was seen in all patients except one who had subclinical hyperthyroidism. Graves' disease was the most common cause of thyrotoxicosis (13/15) and the remaining two patients had subacute thyroiditis and gestational thyrotoxicosis. Hypokalaemia (serum potassium <3.5 mmol/l) was seen in 12 patients, and the mean serum potassium was 3.2±0.9 mmol/l (range: 2.1-4.9). All patients had flaccid weakness, predominantly involving the lower limb with no bulbar, respiratory or cranial nerve involvement. The average duration of paralysis was 10.6±5.7 h (range: 3-28 h). Interpretation & conclusions: Our study demonstrated an early age of presentation and presence of clinical and biochemical thyrotoxicosis in majority of patients with TPP. Hypokalaemia may not always be evident in patients with TPP.

Diffusion tensor imaging in hyperthyroidism: assessment of microstructural white matter abnormality with a tract-based spatial statistical analysis.

BACKGROUND: Metabolic, morphological, and functional brain changes associated with a neurological deficit in hyperthyroidism have been observed. However, changes in microstructural white matter (WM), which can explain the underlying pathophysiology of brain dysfunctions, have not been researched. PURPOSE: To assess microstructural WM abnormality in patients with untreated or newly diagnosed hyperthyroidism using tract-based spatial statistics (TBSS). MATERIAL AND METHODS: Eighteen patients with hyperthyroidism and 14 age- and sex-matched healthy controls were included in this study. TBSS were used in this diffusion tensor imaging study for a whole-brain voxel-wise analysis of fractional anisotropy, mean diffusivity, axial diffusivity (AD), and radial diffusivity (RD) of WM. RESULTS: When compared to the control group, TBSS showed a significant increase in the RD of the corpus callosum, anterior and posterior corona radiata, posterior thalamic radiation, cingulum, superior longitudinal fasciculus, and the retrolenticular region of the internal capsule in patients with hyperthyroidism (P < 0.05), as well as a significant decrease in AD in the anterior corona radiata and the genu of corpus callosum (P < 0.05). CONCLUSION: This study showed that more regions are affected by the RD increase than the AD decrease in the WM tracts of patients with hyperthyroidism. These preliminary results suggest that demyelination is the main mechanism of microstructural alterations in the WM of hyperthyroid patients.

Serum Elabela Levels Are Elevated in Patients with Hyperthyroidism.

The apelinergic system plays an important role in the modulation of the cardiovascular system via the apelin peptide and the apelin receptor (APJ receptor). Apelin and elabela, also known toddler, are peptide ligands for the apelin receptor. These two peptides show similar biological actions, such as vasodilatation, increased myocardial contractility, angiogenesis, and energy metabolism. However, the serum levels of elabela in patients with hyperthyroidism are not well known. The aim of this study was to investigate the changes in serum elabela levels in patients with hyperthyroidism and its association with hypertension. This cross-sectional study included 74 patients with newly diagnosed hyperthyroidism due to Graves' disease and 20 healthy individuals. Serum elabela levels were measured by enzyme-linked immunosorbent assay. The patients were divided into two groups: hyperthyroid patients without hypertension (n = 51) and those with hypertension (n = 23). Basal heart rate, serum glucose and high-sensitive C reactive protein were significantly higher in hyperthyroid patients with and those without hypertension than in healthy controls (p < 0.05 for each). Serum elabela levels were significantly elevated in hyperthyroid patients compared with healthy controls, with higher serum elabela levels found in hyperthyroid patients with hypertension than those without hypertension. Linear regression analysis showed that serum elabela levels were correlated with systolic blood pressure (p < 0.001). In conclusion, serum elabela levels were significantly increased in patients with hyperthyroidism, especially in hyperthyroid patients with hypertension. Elevation in serum elabela levels may contribute to alleviation of cardiovascular complications of hyperthyroidism and hypertension.

Changes in left ventricular function and contractile homogeneity in young adults with newly diagnosed hyperthyroidism due to Graves' disease.

PURPOSE: The aim of this study was to investigate myocardial dysfunction and mechanical abnormalities in young patients with Graves' disease before therapy, using two-dimensional speckle tracking echocardiography. METHODS: We performed a comprehensive transthoracic echocardiographic examination, including segmental and global radial strain, and time-to-peak radial strain, in 47 young patients with hyperthyroidism and 34 healthy adults. The time-to-peak radial strain was corrected by RR interval. The variables derived from radial myocardial deformation by the six-basal, six-mid, and six-apical segmental model were compared to investigate the difference of the myocardial function between the two groups. RESULTS: Early diastolic mitral inflow velocity, E/A ratio, early diastolic mitral annular velocity, and e'/a' ratio were lower in patients with Graves' disease than in controls. The left ventricular end-diastolic volume, left ventricular end-systolic volume, stroke volume, cardiac output, heart rate, late diastolic mitral inflow velocity, and late diastolic mitral annular velocity were slightly higher in patients than in controls. Radial strain, global radial strain, and corrected time-to-peak radial strain were lower in the patient group. CONCLUSIONS: The decreased radial strain, global radial strain, and corrected time-to-peak radial strain in young patients with newly diagnosed hyperthyroidism due to Graves' disease could serve as an early sign of subclinical cardiac involvement.

The Role of Thyroid Hormones in Heart Failure.

Cardiovascular diseases are the leading cause of death worldwide. Heart failure is the terminal manifestation of cardiovascular diseases, and its morbidity and mortality remain high. The prevalence of heart failure with preserved ejection fraction (HFpEF) among heart failure patients remains uncertain. However, recent studies have found that it ranged from 40 to 71%. There is still no effective treatment for HFpEF. Thyroid hormones (TH) have central regulatory actions in the cardiovascular system, particularly in the heart. Changes in plasmatic or tissue thyroid hormone levels are associated with significant alterations in cardiovascular function. A significant proportion of patients with heart failure presents some form of thyroid dysfunction including hypothyroidism, hyperthyroidism, and low T3 syndrome. Furthermore, thyroid hormones can vary at a local level independently of the serum TH levels. This may lead to local cardiac hypothyroidism in heart failure. Based on these findings and the role that TH play in cardiovascular regulation, they were proposed as a potential target for heart failure therapy. Several clinical and experimental studies have shown beneficial effects of TH supplementation. Data from epidemiological studies supports a higher risk of heart failure and a worse prognosis in heart failure patients with low levels of TH. In addition, animal studies and small clinical studies suggest that TH supplementation may improve cardiac function in heart failure. Although further studies are needed to evaluate the safety and efficacy of TH in this context, the available evidence suggests that TH modulation is a promising therapeutic approach to heart failure.

Subclinical thyroid dysfunction is associated with adverse prognosis in heart failure patients with reduced ejection fraction.

BACKGROUND: Subclinical thyroid dysfunction whose typical patterns include subclinical hypothyroidism and subclinical hyperthyroidism, has been indicated to be associated with an increased risk of heart failure (HF). However, the relationship between subclinical thyroid dysfunction and the clinical outcomes of HF patients is uncertain. This meta-analysis was conducted to assess the association between subclinical thyroid dysfunction and the clinical outcomes of HF patients. METHODS: Pubmed, Embase, Web of Science and Cochrane Central Register of Clinical Trials were searched for eligible studies published up to August 1, 2018 which reported the association between subclinical thyroid dysfunction and the clinical outcomes of HF patients. The pooled hazard ratio (HR) with the corresponding 95% confidence interval (CI) was used to assess the association. RESULTS: Fourteen studies met the eligibility criteria and a total of 21,221 patients with heart failure were included in the meta-analysis. Compared with HF patients with euthyroidism, the pooled HR of subclinical hypothyroidism for all-cause mortality was 1.45 (95% CI 1.26-1.67) in a randomized effects model with mild heterogeneity (I2 = 40.1, P = 0.073). The pooled HR of subclinical hypothyroidism for cardiac death and/or hospitalization was 1.33 (1.17-1.50) in a randomized effects model with moderate heterogeneity (I2 = 69.4, P < 0.001). Subclinical hyperthyroid can increase the risk of all-cause mortality without heterogeneity (HR 1.31, 95% CI 1.10-1.55, I2 = 25.5%, P = 0.225) but have no influence on the risk of cardiac death and/or hospitalization (HR 1.03, 95% CI 0.87-1.23, I2 = 0.0%, P = 0.958). These significant adverse associations were also retained in subgroup analysis. Sensitivity analysis demonstrated the stability of the results of our meta-analysis. CONCLUSIONS: Both subclinical hypothyroidism and subclinical hyperthyroidism are associated with adverse prognosis in patients with HF. Subclinical thyroid dysfunction may be a useful and promising predictor for the long-term prognosis in HF patients.

Redox unbalance in the hyperthyroid cat: a comparison with healthy and non-thyroidal diseased cats.

BACKGROUND: Feline hyperthyroidism, the most common endocrinopathy in older cats, provides a spontaneous model for human thyrotoxicosis. Human thyrotoxicosis is associated with redox unbalance, which may result in organ damage. The redox status of hyperthyroid cats is largely unknown. The aims of the present study were to compare the redox status of cats with hyperthyroidism with that of healthy cats and cats with chronic non-thyroidal illness. RESULTS: Forty cats with untreated hyperthyroidism (group H), 45 chronically ill cats with non-thyroidal illness (group I), and 39 healthy cats (group C) were recruited for this observational cross-sectional study. All cats were screened for redox status markers. Determinable reactive oxygen metabolites (d-ROMs) were used as oxidative stress markers. Antioxidant status was determined using the OXY-Adsorbent test to quantify the plasma barrier to oxidation. The Oxidative Stress index (OSi) was calculated as the ratio of d-ROMs and OXY-Adsorbent test values. Data were compared by ANOVA with Tukey's multiple comparisons post-hoc test. The dROMs of group H (193 ± 47 CarrU) were significantly higher (p < 0.001) than those of the healthy cats (103 ± 17 CarrU). The OXY-Adsorbent test results in group H (265 ± 68 µmol HClO/ml) were significantly lower than those in healthy cats (390 ± 83 µmol HClO/ml; p < 0.01) and chronically ill cats (306 ± 45 µmol HClO/ml, p < 0.05). Moreover, the Osi value in group H (0.8 ± 0.2 CarrU/µmol HClO/ml) was significantly higher (p < 0.001) than that of the healthy cats (0.3 ± 0.1 CarrU/µmol HClO/ml). CONCLUSIONS: As described in humans with hyperthyroidism, feline hyperthyroidism is associated with redox unbalance. Free radical production is increased in hyperthyroid cats and their antioxidant depletion seems to be more severe than in cats with non-thyroidal illnesses. Our results support the rationale for a clinical trial investigating the potential positive effects of antioxidant supplementation to cats with hyperthyroidism.

Interference of High Dose Biotin Supplementation with Thyroid Parameters in Immunoassays Utilizing the Interaction between Streptavidin and Biotin: a Case Report and Review of Current Literature.

BACKGROUND: Automated immunoassays utilizing the interaction between streptavidin and biotin are widely used. Nonetheless, biotin remains an often overlooked confounder. METHODS: We report the case of a 54-year-old female patient with progressive multiple sclerosis and Hashimoto's thyroiditis who presented herself for a follow-up. Measurements on Roche's cobas® 8000 modular analyzer series suggested severe hyperthyroidism. Initially, no relevant confounders could be identified. RESULTS: All requested thyroid parameters were measured with alternative methods, yielding plausible results. CONCLUSIONS: Biotin is a significant confounder in many immunoassays. Alternative measurement methods or methods of biotin neutralization need to be implemented for certain situations.

Frequency and outcomes of maternal thyroid function abnormalities in early pregnancy.

Thyroid function in pregnant women is of clinical importance considering the crucial role of thyroid hormones during fetal brain development, but the current level of evidence is insufficient to recommend for or against the routine testing of thyroid function in pregnant women. As part of this debate, it is important to evaluate the frequency of undiagnosed and untreated thyroid function abnormalities in pregnant women and to address challenges related to the biochemical assessment of maternal thyroid function in early pregnancy. A hypothesis of fetal programming by maternal thyroid disease has been proposed, but more evidence in humans is needed to extend the hypothesis and to evaluate child neurodevelopmental outcomes after in utero exposure to different abnormalities in maternal thyroid function. The nationwide registers in the Nordic countries provide unique opportunities within reproductive epidemiology to study the impact of various in utero exposures, and stored blood samples from pregnant women in nationwide birth cohorts provide a valuable source for the establishment of pregnancy specific reference ranges. This review addresses the frequency and outcomes of thyroid function abnormalities in pregnant women mainly focusing on observational studies that combine data from the Danish nationwide registers and biological specimens from the Danish National Birth Cohort. Dynamic changes in the reference range of maternal TSH and free T4 during the first trimester of pregnancy are described and discussed. A high frequency of unidentified maternal thyroid function abnormalities is illustrated, and outcomes of child neurodevelopment are evaluated according to subtypes and severity of maternal thyroid dysfunction.

Prospective Echocardiographic Evaluation of the Right Ventricle and Pulmonary Arterial Pressure in Hyperthyroid Patients.

BACKGROUND: Pulmonary arterial hypertension (PAH) occurs in 35% to 65% of hyperthyroid patients. Despite this high frequency, only a few authors have examined the effects of hyperthyroidism treatment on PAH and the right ventricle. We evaluated the effects of hyperthyroidism and its reversal on cardiovascular structure and function using Doppler echocardiography. METHODS: We prospectively evaluated 32 patients (42.5±11.9years old) with thyrotoxicosis. Exclusion criteria included previous cardiovascular disease. An echocardiogram was performed at the time of hyperthyroidism diagnosis and after normalisation of free thyroxine (T4) levels. Patients were divided into two groups according to the presence or absence of PAH at the diagnosis, or at two moments, before and after T4 normalisation. RESULTS: Graves' disease was the most frequent aetiology (75%) of hyperthyroidism. Pulmonary arterial hypertension was observed in 43.8% of patients. Free T4 concentration was higher in PAH than non-PAH patients. Free T4 normalised after 5 (2.0-10.5; median and percentiles) months of treatment. Cardiac chamber sizes and cardiac output were higher in PAH. Right ventricular (RV) systolic function was impaired in PAH. Cardiac output and free T4 (r=0.42; p<0.05) correlated with pulmonary artery systolic pressure (PASP). Cardiac chamber size, cardiac output, left ventricular ejection fraction, and PASP (34.0±8.6 to 21.7±4.5mmHg) reduced after treatment. Right ventricular myocardial performance index and fractional area change improved after T4 normalisation. CONCLUSIONS: Pulmonary arterial hypertension is highly prevalent in hyperthyroid patients and is combined with increased cardiac chambers size and cardiac output, and impaired RV function. Cardiovascular changes are reversible after T4 normalisation in patients without cardiovascular disease.

An underestimated comorbidity of COPD: Thyroid dysfunction.

Chronic obstructive pulmonary disease (COPD) has many systemic effects influencing morbidity and mortality of the disease. Thyroid diseases which are more common in COPD patients than who do not have COPD are underestimated despite important clinical consequences. Similar to general population, thyroid dysfunctions are more common in females than males among COPD patients. Both hypothyroidism and hyperthyroidism may be associated to COPD. As well as systemic inflammation hypoxia, age, glucocorticoid use and smoking are some of the effective factors on developing thyroid dysfunction in COPD patients. In this article thyroid dysfunctions that are underrecognized comorbidities of COPD patients, their mechanisms of action and clinical outcomes were reviewed.