Thyroid hormone and the cardiovascular system

Acute Exercise Promptly Normalizes Myocardial Myosin Heavy-Chain Isoform mRNA Composition in Diabetic Rats: Implications for Diabetic Cardiomyopathy

Background and Objectives: The acute effects of exercise on the myosin heavy-chain (MHC) isoform mRNA expression and the upstream transcription factors in diabetic and non-diabetic hearts remain unexplored. We aimed to determine the acute effect of a single exercise session on the expression of left ventricular MHC, MHC-α and MHC-β, and thyroid receptor (TR), TR-α1 and TR-β, isoform mRNA in diabetic and non-diabetic rats. Materials and Methods: Sprague-Dawley rats were assigned to four groups: non-diabetic control (CS), diabetic exercise (DIEX), sedentary diabetic (DIS), and non-diabetic exercise (CEX). Diabetes was induced via streptozotocin injection (55 mg/kg). DIEX and CEX rats performed an exercise session (60 min at 50 m/min and 0% grade) 6-7 weeks after diabetes induction. Results: MHC-α mRNA was lower in DIS (p = 0.03) and not different in DIEX (p = 0.1) relative to CS. DIS showed higher MHC-β mRNA than the non-diabetic rats, CS and CEX (p = 0.02 and p = 0.009, respectively). MHC-β mRNA in DIEX was normalized to non-diabetic levels in CS (p = 0.3). TR-α1 was higher in DIS and not different in DIEX relative to CS and CEX (p = 0.03 and p = 1.0, respectively). In CEX, exercise did not change MHC-α, MHC-β, and TR-α1 relative to CS (p = 1.0). TR-β was not different between groups. Conclusion: In conclusion, exercise appears to acutely normalize the myocardial MHC and TR isoform mRNA expression only in the diabetic heart. These responses may induce therapeutic mechanisms other than changing the MHC isoform composition.

Thyroid hormone disorder and the heart: The role of cardiolipin in calcium handling

NEW FINDINGS

What is the central question of this study? Do alterations in thyroid status affect haemodynamic parameters and echocardiographic measurements in the rat postnatal heart, and calcium handling, contractility, relaxation and cardiolipin content in isolated rat cardiomyocytes? What is the main finding and its importance? An imbalance in phospholipids of the mitochondrial membrane such as cardiolipin is related to defects in mitochondrial function. T3 -dependent cardiolipin signals contribute to the maintenance of mitochondrial homeostasis and involve Ca2+ handling, this pathway being more important in hypothyroidism.

ABSTRACT

The objective of this study was to evaluate whether alterations in thyroid status affect (1) haemodynamic parameters and echocardiographic measurements in the rat postnatal heart, and (2) calcium handling, contractility, relaxation and cardiolipin content in isolated rat cardiomyocytes. Sprague-Dawley rats aged 2 months treated with T3 (hyperthyroid, 20 μg/100 g body weight) or 0.02% methimazole (hypothyroid, w/v) for 28 days. Heart function was evaluated by echocardiography. Measurements of mean arterial pressure (MAP), heart rate, Ca2+ transients, cardiomyocyte shortening, number of spontaneous contractions per minute and cardiolipin (CL) content were performed. Thyroid disorders were associated with changes in pacemaker activity without modifications of MAP. Thyroid disorder induced changes in left ventricular diameter which were correlated with modifications of cardiac contractility (altered cell shortening and sarcoplasmic reticulum Ca2+ content). Endocrine disorders altered cardiomyocyte relaxation (reduction in the time to 50% re-lengthening and the time to 50% Ca2+ decay). Thyroid disorder increased the number of spontaneous contractions per minute (an index of pro-arrhythmogenic behaviour). CL content was increased only in hypothyroid rats. Changes in CL content, CL composition and CL-protein interaction in mitochondria from hypothyroid animals are responsible for alterations of contractile and relaxation cardiac function. This mechanism may be not be involved in T3 -treated rats. Maintenance of euthyroidism is of crucial importance to preserve cardiac performance. An imbalance in relation to phospholipids of the mitochondrial membrane such as CL is related to defects in mitochondrial function. T3 -dependent CL signals contribute to the maintenance of mitochondrial homeostasis and involve Ca2+ handling, this pathway being more important in hypothyroidism.

Promoter sequence interaction and structure based multi-targeted (redox regulatory genes) molecular docking analysis of vitamin E and curcumin in T4 induced oxidative stress model using H9C2 cardiac cell line

A positive association between oxidative stress and hyper-thyroid conditions is well established. Vitamin E (VIT-E) and curcumin (CRM) are considered as potent antioxidant small molecules. Nuclear factor erythroid 2-related factor 2(NRF-2) is known to bind with antioxidant response element and subsequently activate expression of antioxidant enzymes. However, the activation of NRF-2 depends on removal of its regulator Kelch-like ECH-associated protein 1(NRF-2). In the current study, an attempt is made to demonstrate whether effects of VIT-E and CRM are due to direct interaction with the target proteins (i.e. NRF-2, NRF-2, SOD, catalase and LDH) or by possible interaction with the flanking region of their promoters by in silico analysis. Further, these results were corroborated by pretreatment of H9C2 cells (1 x 10⁶ cells per mL of media) with VIT-E (50 μM) and/or CRM (20 μM) for 24 h followed by induction of oxidative stress via T4 (100 nm) administration and assaying the active oxygen metabolism. Discriminant function analyses (DFA) indicated that T4 has a definite role in increasing oxidative stress as evidenced by induction of ROS generation, increase in mitochondrial membrane potential and elevated lipid peroxidation (LPx). Pretreatment with the two antioxidants have ameliorative effects more so when given in combination. The decline in biological activities of the principal antioxidant enzymes SOD and CAT with respect to T4 treatment and its restoration in antioxidant pretreated group further validated our in silico data. Communicated by Ramaswamy H. Sarma.

Myxedema Coma: A Rare Case of Shock Post-Pericardial Window Procedure

The clinical features of severe hypothyroidism vary in presentation, ranging from subclinical symptoms to multiorgan failure referred to as myxedema coma. The cornerstone treatments of myxedema coma include aggressive thyroid hormone replacement combined with excellent supportive care in the intensive care unit. We report a rare case of a 56-year-old female with history of hypothyroidism treated with levothyroxine, who developed myxedema coma post-pericardial window surgery for a large pericardial effusion. She was supported with substantial doses of vasopressors and inotropes for shock. In addition, she was initiated on lung-protection ventilation for acute respiratory distress syndrome. After the diagnosis of myxedema coma was made, she was started on intravenous levothyroxine and hydrocortisone with great sustained clinical response. This case illustrated myxedema coma as an unusual cause of shock in post-operative patients with past medical history of hypothyroidism.

Cardiovascular Manifestations in Hyperthyroidism: A Cross-Sectional Study in a Tertiary Care Hospital in South India

Background

The involvement of the heart in hyperthyroidism patients has a considerable prognostic value and causes significant morbidity and mortality. However, very little research, particularly among the Indian population, has addressed the most critical cardiovascular symptoms of hyperthyroidism, so this study aimed to assess the cardiovascular manifestations of hyperthyroidism.

Method

The current cross-sectional investigation involved 140 newly diagnosed and untreated confirmed cases of hyperthyroidism of any etiology for nine months. A structured data collection schedule was used to collect patient-specific and pertinent information during OPD hours or after admission. T4, T3, and TSH were measured in 10 mL of blood from each patient. The information was entered into a Microsoft Excel spreadsheet. All tests were carried out with a 5% level of significance.

Results

The mean age of study subjects was 43.2 years. Females made up 85.0% of the subjects in the current study, while males made up 15.0%. The etiology of hyperthyroidism was primarily due to Grave’s disease (59.3%). Heat intolerance (67.9%) was the most typical presenting symptom among the patients. The most common cardiac symptom was palpitation among 76.4% of subjects in the present study. Upon clinical examination, 80.7% of subjects had tachycardia. The ECG showed atrial fibrillation (AF) in 17.9% of subjects. The echocardiogram (ECHO) findings revealed systolic dysfunction in 17.8% of subjects.

Conclusion

Since cardiovascular manifestations are common in patients with thyroid disease and may be the only manifestation of thyroid disease, it is suggested that all patients with thyroid disorders be checked for cardiovascular manifestations. In addition, thyroid function tests should be performed in all patients with unexplained cardiovascular disease.

New-Onset Hypothyroidism Manifesting As Myxedema Coma: Fighting an Old Enemy

Myxedema coma (MC) is a rare manifestation of severe hypothyroidism. This is a true endocrine emergency that may remain unrecognized. We present a case of a 49-year-old man who presented to the emergency department with generalized weakness and confusion. He was found to have low temperature, bradycardia, hypoxia, hypotension, glucose of 59 mg/dL, normal electrolytes, thyroid-stimulating hormone of 154 IU/mL, and free T4 of 0.1 ng/dL. His anti-peroxidase antibody level was 99 IU/mL. Echocardiography revealed a normal ejection fraction and no evidence of pericardial effusion. On the basis of his presentation and laboratory findings, he was diagnosed with MC, intubated, and admitted to the intensive care unit. Thyroid hormone replacement and glucocorticoid treatment were initiated immediately. After the clinical improvement, the patient was extubated. MC is associated with a high mortality rate and requires prompt recognition and treatment. This rare case reminds us that MC might still be the first manifestation of primary hypothyroidism, although considered an “old enemy”.

Cardiovascular Involvement in Thyrotoxicosis Resulting in Heart Failure: The Risk Factors and Hemodynamic Implications

Thyrotoxicosis is a clinical syndrome with persistently elevated concentrations of free triiodothyronine, free thyroxine, or both, which correlates with an increased thyroid metabolic function. This article has discussed the direct effect of increased thyroid hormone on the heart, as the thyroid hormone physiologically exhibits a close harmony with hormones of the cardiovascular system. This action can lead to disturbances in hemodynamic stability, exacerbating the possibility of developing complications such as heart failure and life-threatening arrhythmias. This article has also explored the multifaceted pathogenesis of thyrotoxicosis and various pharmacological treatment options, including beta-blockers and anti-thyroid drugs. This article has reviewed numerous studies that have concluded that the main goal of therapy should always aim to normalize thyroid hormone levels based on the etiology of the thyrotoxicosis, although cardiovascular conditions are associated with a higher rate of mortality.

Noncanonical Thyroid Hormone Receptor α Action Mediates Arterial Vasodilation

CONTEXT

Hypothyroidism impairs cardiovascular health and contributes to endothelial dysfunction with reduced vasodilation. How 3,5,3'-triiodothyronine (T3) and its receptors are involved in the regulation of vasomotion is not yet fully understood. In general, thyroid hormone receptors (TRs) either influence gene expression (canonical action) or rapidly activate intracellular signaling pathways (noncanonical action).

OBJECTIVE

Here we aimed to characterize the T3 action underlying the mechanism of arterial vasodilation and blood pressure (BP) regulation.

METHODS

Mesenteric arteries were isolated from male rats, wild-type (WT) mice, TRα knockout (TRα 0) mice, and from knockin mice with a mutation in the DNA-binding domain (TRα GS). In this mutant, DNA binding and thus canonical action is abrogated while noncanonical signaling is preserved. In a wire myograph system, the isolated vessels were preconstricted with norepinephrine. The response to T3 was measured, and the resulting vasodilation (Δ force [mN]) was normalized to maximum contraction with norepinephrine and expressed as percentage vasodilation after maximal preconstriction with norepinephrine (%NE). Isolated vessels were treated with T3 (1 × 10-15 to 1 × 10-5 mol/L) alone and in combination with the endothelial nitric oxide-synthase (eNOS) inhibitor L-NG-nitroarginine methyl ester (L-NAME) or the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin. The endothelium was removed to determine the contribution of T3 to endothelium-dependent vasodilation. The physiological relevance of T3-induced vasodilation was determined by in vivo arterial BP measurements in male and female mice.

RESULTS

T3 treatment induced vasodilation of mesenteric arteries from WT mice within 2 minutes (by 21.5 ± 1.7%NE). This effect was absent in arteries from TRα 0 mice (by 5.3 ± 0.6%NE, P < .001 vs WT) but preserved in TRα GS arteries (by 17.2 ± 1.1%NE, not significant vs WT). Inhibition of either eNOS or PI3K reduced T3-mediated vasodilation from 52.7 ± 4.5%NE to 28.5 ± 4.1%NE and 22.7 ± 2.9%NE, respectively. Removal of the endothelium abolished the T3-mediated vasodilation in rat mesenteric arteries (by 36.7 ± 5.4%NE vs 3.5 ± 6.2%NE). In vivo, T3 injection led to a rapid decrease of arterial BP in WT (by 13.9 ± 1.9 mm Hg) and TRα GS mice (by 12.4 ± 1.9 mm Hg), but not in TRα 0 mice (by 4.1 ± 1.9 mm Hg).

CONCLUSION

These results demonstrate that T3 acting through noncanonical TRα action affects cardiovascular physiology by inducing endothelium-dependent vasodilation within minutes via PI3K and eNOS activation.

An Unusual Presentation of ST Elevation Myocardial Infarction Complicated with Cardiogenic Shock Due to Myxedema Coma: A Case Report

Patient: Male, 70-year-old

Final Diagnosis: Inferior STEMI • myxedema coma

Symptoms: Chest pain • confusion • fatigue

Medication: —

Clinical Procedure: Cardiac catheterization

Specialty: Cardiology • Endocrinology and Metabolic

Clinical manifestation and images of a patient having cardiovascular involvement in myxoedema coma

Myxoedema coma is an endocrine emergency characterised by diminished sensorium associated with features of severe hypothyroidism. The disease carries a high mortality of 30%-60 %. The cardiac manifestation of the disease consists of bradycardia, hypotension, pericardial effusion and certain echocardiographic changes such as heart block and features of hypothermia. Here, we report a case of myxoedema coma with characteristic cardiac manifestations. These manifestations revert promptly on starting treatment, and achieving a eumetabolic status as was demonstrated in this patient.

Hyperthyroidism Is Associated with the Development of Vasospastic Angina, but Not with Cardiovascular Outcomes

Vasospastic angina (VA) is a functional disease caused by the alteration of vasomotor tone. We investigated the association of hyperthyroidism with the development and prognosis of VA. Study data were obtained from a prospective multicenter registry that included patients who had symptoms suggestive of VA. Coronary angiography and an ergonovine provocation test were performed, and patients were classified into a VA and a non-VA group. Among 1239 patients with suspected VA, 831 patients were classified in the VA group. Hyperthyroidism was more common in the VA group than in the non-VA group (10.0% vs. 3.7%, p < 0.001). After adjusting for confounding factors, hyperthyroidism was independently associated with a 3.27-fold increased risk of VA. Especially in women, hyperthyroidism was associated with a 4.38-fold higher risk of VA. All-cause death rates did not differ according to the presence or absence of hyperthyroidism. Hyperthyroidism is independently associated with the occurrence of VA especially in women but did not affect the total death in VA patients. Clinicians need to be aware of the role of thyroid function in patients with suspected VA.

Long term outcomes of infants born by mothers with thyroid dysfunction during pregnancy

According to Barker’s hypothesis, sub-optimal conditions during gestation might affect the predisposition for diseases in adulthood. Alteration in endocrine functions during pregnancy, such us thyroid function or glucose metabolism, are not exempt. It is well known that subclinical hypothyroidism and thyroperoxidase antibodies-positive euthyroidism during early pregnancy are associated with increased risk of gestational diabetes mellitus and both conditions influence pregnancy outcome and newborn development and metabolism at short and long terms. Fetal production of thyroid hormones starts from the 12th week of gestational age. The transplacental passage of maternal thyroxine (T4) is therefore essential for the fetal neurological development, especially during the first half of pregnancy. If this passage is interrupted, such as in premature birth, neonates are more susceptible to develop impaired thyroid function, because of physiological immaturity of their hypothalamic-pituitary-thyroid axis, acute illnesses and stressful events (sepsis, invasive procedures, drugs). The aim of this review is to investigate the short and long term effects of maternal dysthyroidisms on term and preterm newborns, with particular attention to the metabolic and thyroid consequences. Metabolic syndrome, higher body mass index and greater waist circumference, seem to be more prevalent in children of TPO-Ab-positive mothers. Maternal hypothyroidism may be associated with higher risk of gestational diabetes and adverse birth outcomes, such as preeclampsia, preterm delivery, fetal death and low birth weight offspring. In adulthood, preterm (< 37 weeks of gestational age) or low birth weight (<2.500 g) newborns seem to be more susceptible to develop gestational diabetes, preeclampsia, type 2 diabetes mellitus and behavioral alterations. (www.actabiomedica.it)

Symmetric dimethylarginine concentrations in dogs with hypothyroidism before and after treatement with levothyroxine

OBJECTIVES

To evaluate the serum symmetric dimethylarginine (SDMA) and serum creatinine concentrations in a population of hypothyroid dogs at the time of diagnosis and after treatment.

MATERIALS AND METHODS

Serum SDMA and serum creatinine were measured in serum samples of 24 healthy dogs and 24 hypothyroid dogs, at the time of diagnosis (T0) and after supplementation with levothyroxine (T1).

RESULTS

The mean SDMA concentrations (reference intervals [RI] <18 μg/dL and <14 μg/dL depending on the source) were 11.7 ± 3.5 μg/dL, 13.8 ± 3.1 μg/dL and 11.83 ± 2.87 μg/dL in healthy dogs, and in the hypothyroid dogs at T0 and T1, respectively. The SDMA concentrations were higher in the hypothyroid dogs at T0 in comparison with the healthy dogs. Of the hypothyroid dogs, 1 out of 24 had an SDMA concentration above 18 μg/dL and 12 out of 24 above 14 μg/dL at T0. At T1, none of the hypothyroid dogs had SDMA concentrations above 18 μg/dL and two of them had SDMA concentrations above 14 μg/dL. The serum creatinine concentration was higher in the hypothyroid dogs at T0 as compared to the healthy dogs. At T0, 8 out of 24 hypothyroid dogs had serum creatinine concentrations above the RI (>1.4 mg/dL). In all but one dog, serum creatinine normalised after treatment.

CLINICAL SIGNIFICANCE

The SDMA and serum creatinine concentrations were higher in hypothyroid dogs at diagnosis as compared to healthy dogs. Serum creatinine concentrations were increased in one-third of the hypothyroid dogs and in the majority of cases normalised after levothyroxine supplementation. SDMA concentrations were rarely above the upper limit of the RI when the higest (<18 μg/dL) cut-off was employed. The diagnostic accuracy of SDMA in dogs with thyroid dysfunction requires additional evaluation.

Evaluation of left atrial and ventricular myocardial functions by three-dimensional speckle tracking echocardiography in patients with euthyroid Hashimoto's thyroiditis

Hashimoto's Thyroiditis (HsT) is one of the most frequently occurring autoimmune diseases, characterized by lymphocytic infiltration, destruction and fibrosis of thyroid tissue and the presence of antibodies to thyroid peroxidase and thyroglobulin. The effects of euthyroid Hashimoto's thyroiditis (eHsT) on cardiovascular system are unclear. We aimed to identify if any deteriorations in LA and LV myocardial functions in patients with eHsT by 3D-STE in the current study. Fifty eight patients with eHsT and 60 age- and gender-matched controls were enrolled into the study. All participants underwent laboratory analyses which included thyroid hormones and thyroid autoantibody levels; and conventional 2D echocardiographic and 3D-STE analyses were performed. The mean age of the study patients was 34.5 ± 9 years, and 68.6% were female. Left ventricular global longitudinal strain (LV-GLS) was significantly depressed in the eHsT (+) group than in the control group (- 15.3 ± 3.6 vs. - 22.8 ± 3.8, p < 0.001). The LV-GLS was found to be disrupted linearly as thyroid autoantibodies increased (r = 0.684 for anti-TPO-ab and LV-GLS; r = 0.649 for anti-Tg-ab and LV-GLS). The present study demonstrated that 3D-STE is useful in the early detection of LV myocardial dysfunction in patients with eHsT. We found that eHsT had a negative effect on LV myocardial dynamics. According to these findings, these myocardial alterations that are present early in the disease process may be considered as a reason to start medical treatment earlier, even at the euthyroid stage to prevent LV myocardial impairment.

Impact of hyperthyroidism on cardiac hypertrophy

The cardiac growth process (hypertrophy) is a crucial phenomenon conserved across a wide array of species and it is critically involved in maintenance of cardiac homeostasis. This process enables organism adaptation to changes of systemic demand and occurs due to a plethora of responses, depending on the type of signal or stimuli received. The growth of cardiac muscle cells in response to environmental conditions depends on the type, strength and duration of stimuli, and results in adaptive physiologic response or non-adaptive pathologic response. Thyroid hormones (TH) have a direct effect on the heart and induce a cardiac hypertrophy phenotype, which may evolve to heart failure. In this review, we summarize the literature on TH function in heart presenting results from experimental studies. We discuss the mechanistic aspects of TH associated with cardiac myocyte hypertrophy, increased cardiac myocyte contractility and electrical remodeling as well as the signaling pathways associated. In addition to classical crosstalk with the Sympathetic Nervous System (SNS), emerging work points to the new endocrine interaction between TH and Renin-Angiotensin System (RAS) is also explored. Given the inflammatory potential of the angiotensin II peptide, this new interaction may open the door for new therapeutic approaches that target key mechanisms responsible for TH-induced cardiac hypertrophy.

Subclinical Myocardial Dysfunction Demonstrated by Speckle Tracking Echocardiography in Children with Euthyroid Hashimoto’s Thyroiditis

Objective

Thyroid hormones have an important role in the regulation of the cardiovascular system. The aim of this study was to investigate the presence of subclinical myocardial dysfunction in children with euthyroid Hashimoto’s thyroiditis (eHT) without evident heart disease using tissue doppler imaging (TDI) and speckle tracking echocardiography (STE) methods.

Methods

TDI and STE were peformed in 50 children with eHT and in 35 healthy children. To assess myocardial velocities and time intervals, including peak systolic velocity (Sm), peak early diastolic velocity (Em), peak late diastolic velocity (Am), isovolumetric contraction time (IVCT), isovolumetric relaxation time (IVRT) and ejection time (ET), TDI was performed at the base of the interventricular septum (IVS) and in the left and right ventricles (LV and RV, respectively). Analysis of myocardial deformation by STE including strain (S) and strain rate (SR) was performed globally in two planes, longitudinal (L) and mid-circumferential (C) in LV [LV global longitudinal strain (LVGLS), LV global longitudinal strain rate (LVGLSR), LV global circumferential strain (LVGCS), LV global circumferential strain rate (LVGCSR)] and RV [(RV global longitudinal strain (RVGLS), RV global longitudinal strain rate (RVGLSR)].

Results

Among TDI parameters, ET at LV and IVS were significantly lower, IVRT and myocardial performance index at LV and IVS were significantly higher in the eHT group compared to controls (p=0.001). There were no significant differences in Sm, Em, Am and IVCT values between patients and controls. LVGLS, LVGLSR, LVGCS and LVGCSR values were significantly lower in patients than controls (p=0.01). There was a negative correlation between thyroid antibody levels and LV global longitudinal and circumferential strain and strain rate values (TPO-Ab and Tg-Ab between LVGLS, LVGLSR, LVGCS and LVGCSR; r=-411, p<0.001; r=-541, p<0.001; r=-430, p<.0.001; r=-502, r<0.01 and r=-397, p<0.001; r=-473, p<0.001; r=-519, p<0.001; r=-421, p<0.00, respectively).

Conclusion

The results show that myocardial function in children with eHT is impaired in the absence of any clinical symptoms and that conventional echocardiography is inadequate to determine these changes.

Ubiquitin proteasome system (UPS) activation in the cardiac hypertrophy of hyperthyroidism

Ubiquitin proteasome system (UPS) is the main proteolytic pathway in eukaryotic cells. Changes in proteasome expression and activity have been associated to cardiovascular diseases as cardiac hypertrophy. Considering that cardiac hypertrophy is commonly associated to hyperthyroidism condition, the present study aimed to investigate the contribution of UPS in cardiac hypertrophy induced by thyroid hormones. Hyperthyroidism was induced in male Wistar rats by intraperitoneal injections of triiodothyronine (T3; 7  μg/100 g of body weight) for 7 days and confirmed by raised levels of total T3 and decreased levels of total T4. In addition, systolic blood pressure and heart rate were significantly increased in hyperthyroid group. Cardiac hypertrophy was confirmed in hyperthyroid group by increased heart weight/tibia length ratio and by increased α-MHC/β-MHC relative expression. Both catalytic (20SPT) and regulatory subunits (19SPT) of the constitutive proteasome were upregulated in hyperthyroid hearts. In addition, the transcripts that encode immunoproteasome subunits were also elevated. Furthermore, ATP-dependent chymotrypsin-like activity (26SPT) was significantly increased in hyperthyroid group. Despite the upregulation and activation of UPS in hyperthyroid hearts, the content of polyubiquitinated proteins was unaltered in relation to control. Together, these results evidence the activation of cardiac proteasome by thyroid hormones, which possibly contribute to the maintenance of protein quality control and regulation of cardiac hypertrophy in response to thyroid hormones.

Critical Consideration of Myxedema Coma in the Postoperative Setting: A Case Report

Myxedema coma is a rare but highly fatal condition with reported mortality >40%-50%. Early recognition and prompt treatment are critical for survival. Here we describe a case of possible postoperative myxedema coma after subacute neck hematoma evacuation after hemithyroidectomy in a patient on concurrent amiodarone therapy. Symptoms included somnolence, hypothermia, and prolonged QTc with torsades de pointes resistant to magnesium therapy requiring defibrillation and overdrive pacing. Consideration of the possible diagnosis of myxedema coma resulted in prompt therapy and symptom resolution within 48 hours. Thyroid disorders, although rare, should be considered in the postoperative setting.

Analysis in Choroidal Thickness in Patients with Graves' Ophthalmopathy Using Spectral-Domain Optical Coherence Tomography

Objectives

The objective of the study is to observe changes in choroidal thickness (CT) in patients with Graves' ophthalmopathy using spectral-domain optical coherence tomography (SD-OCT).

Methods

The right eyes of 36 patients (27 females and 9 males) with Graves' ophthalmopathy (GO) and those of 36 age-, gender-, and diopter-level-matched healthy participants were evaluated. The patients' data were obtained within 3 months after the onset of Graves' disease (GD). Thyroid hormone levels and thyroid-stimulating hormone receptor antibody (TRAb) levels were measured, and the degree of exophthalmos was measured in all patients. Activity is measured by the clinical activity score (CAS). A horizontal scan centered on the fovea was performed in all participants. Five points of choroidal thickness were measured at the fovea (SFCT) and at 1500 μm nasal (N1500), 3000 μm nasal (N3000), 1500 μm temporal (T1500), and 3000 μm temporal (T3000) to the fovea.

Results

The CT measurements obtained were (mean ± SD) 313.47 ± 100.32 μm, 279.22 ± 85.80 μm, 214.64 ± 75.52 μm, 313.19 ± 80.36 μm, and 298.14 ± 82.75 μm in patients with GO and were 256.33 ± 50.18 μm, 223.14 ± 59.61 μm, 176.69 ± 60.66 μm, 250.92 ± 52.184 μm, and 239.47 ± 60.35 μm in the control group at the foveal, N1500, N3000, T1500, and T3000 measurement points, respectively. The CT in GO patients was significantly increased at all the points compared with the control group (P < 0.05). There was no relationship between the CT and CAS, the degree of exophthalmos, triiodothyronine (T3), tetraiodothyronine (T4), thyroid-stimulating hormone (TSH), or TRAb levels in GO.

Conclusions

CT was found to be increased in GO patients and had poor relationship with CAS, exophthalmos, and thyroid function tests.

The effect of levothyroxine treatment on left ventricular function in subclinical hypothyroidism

OBJECTIVE

Treatment of subclinical hypothyroidism (ScH), especially the mild form of ScH, is controversial because thyroid hormones influence cardiac function. We investigate left ventricular systolic and diastolic function in ScH and evaluate the effect of 5-month levothyroxine treatment.

SUBJECTS AND METHODS

Fifty-four patients with newly diagnosed mild ScH (4.2 <TSH < 10.0 mU/L) and 30 euthyroid subjects matched by age were analysed. Laboratory analyses and an echocardiography study were done at the first visit and after 5 months in euthyroid stage in patients with ScH.

RESULTS

Compared to healthy controls, patients with ScH had a lower E/A ratio (1.03 ± 0.29 vs. 1.26 ± 0.36, p < 0.01), higher E/e' sep. ratio (762 ± 2.29 vs. 6.04 ± 1.64, p < 0.01), higher myocardial performance index (MPI) (0.47 ± 0.08 vs. 0.43 ± 0.07, p < 0.05), lower global longitudinal strain (GLS) (-19.5 ± 2.3 vs. -20.9 ± 1.7%, p < 0.05), and lower S wave derived by tissue Doppler imaging (0.077 ± 0.013 vs. 0.092 ± 0.011 m/s, p < 0.01). Levothyroxine treatment in patients with ScH contributed to higher EF (62.9 ± 3.9 vs. 61.6 ± 4.4%, p < 0.05), lower E/e' sep. ratio (6.60 ± 2.06 vs. 762 ± 2.29, p < 0.01), lower MPI (0.43 ± 0.07 vs. 0.47 ± 0.08%, p < 0.01), and improved GLS (-20.07 ± 2.7 vs. -19.55 ± 2.3%, p < 0.05) compared to values in ScH patients at baseline. Furthermore, in all study populations (ScH patients before and after levothyroxine therapy and controls), TSH levels significantly negatively correlated with EF (r = -0.15, p < 0.05), E/A (r = -0.14, p < 0.05), GLS (r = -0.26, p < 0.001), and S/TDI (r = -0.22, p < 0.01) and positively correlated with E/e' sep. (r = 0.14, p < 0.05).

CONCLUSION

Patients with subclinical hypothyroidism versus healthy individuals had subtle changes in certain parameters that indicate involvement of systolic and diastolic function of the left ventricle. Although the values of the parameters were in normal range, they were significantly different compared to ScH and the control group at baseline, as well as to the ScH groups before and after treatment.The results of our study suggest that patients with ScH must be followed up during treatment to assess improvement of the disease. Some of the echocardiography obtained parameters were reversible after levothyroxine therapy.

Thyroid hormones stimulate L-arginine transport in human endothelial cells

Thyroid hormone activity is associated with L-arginine metabolism and nitric oxide (NO) production, which participate in the cardiovascular manifestations of thyroid disorders. L-arginine transporters play an important role in activating L-arginine uptake and NO production. However, the effects of thyroid hormones on L-arginine transporters in endothelial cells have not yet been evaluated. The following methods were used. We measured L-arginine uptake, mRNA expression of L-arginine transporters, endothelial nitric oxide synthase (eNOS) mRNA and NO generation after the administration of T3, T4 and the T3 analog, 3,3′,5-triiodothyroacetic acid TRIAC in human umbilical vein endothelial cells (HUVECs). We also analyzed the role of αvβ3 integrin and of phosphatidyl-inositol-3 kinase (PI3K), mitogen-activated protein kinases (MAPKs: ERK1/2, p38 and SAPK-JNK) and intracellular calcium signaling pathways as underlying mechanisms. To this end, αvβ3 integrin was pharmacologically inhibited by tetraiodothyroacetic acid (TETRAC) or genetically blocked by silencing αv mRNA and PI3K, MAPKs and intracellular calcium by selective inhibitors. The following results were obtained. Thyroid hormones and the T3 analog TRIAC increased L-arginine uptake in HUVECs, the sodium-independent y+/CAT isoforms, except CAT2b, sodium-dependent y+L system and sodium-independent system b0,+L-arginine transporters, eNOS mRNA and NO production. These effects were suppressed by αvβ3 integrin inhibition with TETRAC or αv integrin downregulation or by PI3K, MAPK or intracellular Ca2+ signaling inhibitors. In conclusion, we report for the first time that activation of L-arginine uptake by thyroid hormones is related to an upregulation of L-arginine transporters. This effect seems to be mediated by activation of αvβ3 integrin receptor and subsequent PI3K, MAPK and intracellular Ca2+ signaling pathways.

Comatose patient with hypothermia, dyspnea, and general edema in the emergency department: a case report

Patients presenting to the emergency department with hypothermia are rare and often require prompt diagnosis and management. Myxedema coma, which may cause severe hypothermia, is a true endocrine emergency requiring early and appropriate treatment. We report on a 47-year-old woman with a history of hyperthyroidism who underwent thyroidectomy 5 years previously, with no regular medication or examinations. She presented to the emergency department with a 1-month history of progressive dyspnea associated with general weakness. She also showed hypothermia, decreased mental status, and general edema. Echocardiography revealed increased pericardial effusion without tamponade. Laboratory examination suggested myxedema coma and hypothyroidism. She received thyroxine, glucocorticoid supplement, and intensive supportive care, after which she gradually improved and was discharged. This case suggests that myxedema coma should be considered in patients with hypothyroidism or a history of thyroidectomy who present with change in consciousness, hypothermia, or other symptoms related to critical or slow presentation in multiple organs. Moreover, long-standing hypothyroidism or precipitating acute events such as sepsis, cerebrovascular accidents, gastrointestinal bleeding, cold exposure, trauma, and some medications may also cause myxedema coma. Myxedema coma is associated with a high mortality, and patients suspected to be suffering from this condition should be treated without delay.

Resting-state brain correlates of instantaneous autonomic outflow

A prominent pathway of brain-heart interaction is represented by autonomic nervous system (ANS) heartbeat modulation. While within-brain resting state networks have been the object of intense functional Magnetic Resonance Imaging (fMRI) research, technological and methodological limitations have hampered research on the central correlates of cardiovascular control dynamics. Here we combine the high temporal and spatial resolution as well as data volume afforded by the Human Connectome Project with a probabilistic model of heartbeat dynamics to characterize central correlates of sympathetic and parasympathetic ANS activity at rest. We demonstrate an involvement of a number of brain regions such as the Insular cortex, Frontal Gyrus, Lateral Occipital Cortex, Paracingulate and Cingulate Gyrus and Precuneous Cortex, as well as subcortical structures (Thalamus, Putamen, Pallidum, Brain-Stem, Hippocampus, Amygdala, and Right Caudate) in the modulation of ANS-mediated cardiovascular control, possibly indicating a broader definition of the central autonomic network (CAN). Our findings provide a basis for an informed neurobiological interpretation of the numerous studies which employ HRV-related measures as standalone biomarkers in health and disease.

Post-thyroidectomy hypothyroidism increases the expression and activity of ectonucleotidases in platelets: Possible involvement of reactive oxygen species

Signaling mediated by purines is a widespread mechanism of cell-cell communication related to vasomotor responses and the control of platelet function in the vascular system. However, little is known about the involvement of this signaling as well as the role of reactive oxygen species (ROS) in the development of hypothyroidism. Therefore, the present study investigates changes in the purinergic system, including enzyme activities and expression in platelets, and oxidative profiles in patients with post-thyroidectomy hypothyroidism. The nucleoside triphosphate diphosphohydrolase 1 (NTPDase/CD39) expression in patients increased by 40%, and the adenosine triphosphate (ATP) or adenosine diphosphate (ADP) hydrolyzing activity increased by 82% and 70%, respectively. The activities of ecto-5´-nucleotidase and adenosine deaminase (ADA) also significantly enhanced (39% and 52%, respectively), which correlates with a 45% decrease in adenosine concentration. Furthermore, these patients demonstrated an increased production of ROS (42%), thiobarbituric acid reactive substances (TBARS) (115%), carbonyl protein (30%) and a decreased glutathione S-transferase (GST) activity (20%). This study demonstrates that hypothyroidism interferes with adenine nucleoside and nucleotide hydrolysis and this is correlated with oxidative stress, which might be responsible for the increase in ADA activity. This increase causes rapid adenosine deamination, which can generate a decrease in their concentration in the systemic circulation, which can be associated with the development of vascular complications.

Functional Effects of Hyperthyroidism on Cardiac Papillary Muscle in Rats

BACKGROUND

Hyperthyroidism is currently recognized to affect the cardiovascular system, leading to a series of molecular and functional changes. However, little is known about the functional influence of hyperthyroidism in the regulation of cytoplasmic calcium and on the sodium/calcium exchanger (NCX) in the cardiac muscle.

OBJECTIVES

To evaluate the functional changes in papillary muscles isolated from animals with induced hyperthyroidism.

METHODS

We divided 36 Wistar rats into a group of controls and another of animals with hyperthyroidism induced by intraperitoneal T3 injection. We measured in the animals' papillary muscles the maximum contraction force, speed of contraction (+df/dt) and relaxation (-df/dt), contraction and relaxation time, contraction force at different concentrations of extracellular sodium, post-rest potentiation (PRP), and contraction force induced by caffeine.

RESULTS

In hyperthyroid animals, we observed decreased PRP at all rest times (p < 0.05), increased +df/dt and -df/dt (p < 0.001), low positive inotropic response to decreased concentration of extracellular sodium (p < 0.001), reduction of the maximum force in caffeine-induced contraction (p < 0.003), and decreased total contraction time (p < 0.001). The maximal contraction force did not differ significantly between groups (p = 0.973).

CONCLUSION

We hypothesize that the changes observed are likely due to a decrease in calcium content in the sarcoplasmic reticulum, caused by calcium leakage, decreased expression of NCX, and increased expression of a-MHC and SERCA2.

Consanguinity and the Risk of Hashimoto's Thyroiditis

BACKGROUND

Hashimoto's thyroiditis (HT) is the most common autoimmune thyroid disease that may lead to hypothyroidism due to progressive destruction of the thyroid. The etiology of HT is unclear. However, it is associated with multiple genetic predispositions. Consanguinity has been associated with an increased susceptibility to different inherited conditions. This study investigated the association between consanguinity and risk of HT for the first time.

METHODS

Using a case-control study design, 298 HT patients were compared with two subject groups: (i) 299 participants with non-HT hypothyroidism, and (ii) 298 healthy control participants. The three groups were age and sex matched. Presence of consanguinity among the parents was compared in these groups, and odds ratios (OR) were calculated to establish a correlation.

RESULTS

Consanguinity significantly increased the risk of HT (compared with healthy subjects; OR = 3.3; p < 0.0001). In addition, consanguinity was a significant risk factor for HT compared with non-HT hypothyroidism patients (OR = 2.8; p < 0.0001). However, the prevalence of consanguinity was not significantly different in non-HT hypothyroidism patients and healthy subjects.

CONCLUSIONS

The results suggest that the risk for HT is increased in consanguineous unions, but no significant increase in the risk of non-HT hypothyroidism was observed. However, for more precise risk estimates, larger studies that include different populations may be helpful. These findings highlight the health impact of consanguinity and have applications in empiric risk estimations in genetic counseling, particularly in countries with high rates of consanguineous marriages.

The role of neuropeptides in adverse myocardial remodeling and heart failure

In addition to traditional neurotransmitters of the sympathetic and parasympathetic nervous systems, the heart also contains numerous neuropeptides. These neuropeptides not only modulate the effects of neurotransmitters, but also have independent effects on cardiac function. While in most cases the physiological actions of these neuropeptides are well defined, their contributions to cardiac pathology are less appreciated. Some neuropeptides are cardioprotective, some promote adverse cardiac remodeling and heart failure, and in the case of others their functions are unclear. Some have both cardioprotective and adverse effects depending on the specific cardiac pathology and progression of that pathology. In this review, we briefly describe the actions of several neuropeptides on normal cardiac physiology, before describing in more detail their role in adverse cardiac remodeling and heart failure. It is our goal to bring more focus toward understanding the contribution of neuropeptides to the pathogenesis of heart failure, and to consider them as potential therapeutic targets.

Serum Thyroid Stimulating Hormone Levels Are Associated with the Presence of Coronary Atherosclerosis in Healthy Postmenopausal Women

Objectives

Menopause is a natural aging process causing estrogen deficiency, accelerating atherogenic processes including dyslipidemia. Prevalence of thyroid dysfunction is also high in postmenopausal women, and it is known to elevate the risk of cardiovascular disease (CVD). Therefore, we are to study on the associations in between serum thyroid stimulating hormone (TSH) and prevalence of CVD in postmenopausal women who have normal thyroid function.

Methods

We performed a retrospective review of 247 Korean postmenopausal women who visited the health promotion center from January, 2007 to December, 2009. Postmenopausal women with normal serum TSH were included in the study. Coronary atherosclerosis was assessed by 64-row multidetector computed tomography.

Results

In multiple linear regression analysis, serum TSH was associated with serum triglyceride (TG) (β = 0.146, P = 0.023). In multiple logistic regression analysis, increasing age and serum TSH were associated with an increased risk of coronary atherosclerosis in euthyroid postmenopausal women (odds ratio [OR] = 1.107 [1.024-1.197], P = 0.011 and OR = 1.303 [1.024-1.658], P = 0.031, respectively).

Conclusions

It revealed that significant predictor of serum TSH was serum TG, and increasing age and TSH were found to have associations with an increased risk of coronary atherosclerosis in euthyroid postmenopausal women. Screening and assessing risks for CVD in healthy postmenopausal women would be helpful before atherosclerosis develops.

Respiratory manifestations in endocrine diseases

The control mechanisms of respiration as a vital function are complex: voluntary - cortical, and involuntary - metabolic, neural, emotional and endocrine. Hormones and hypothalamic neuropeptides (that act as neurotrasmitters and neuromodulators in the central nervous system) play a role in the regulation of respiration and in bronchopulmonary morphology. This article presents respiratory manifestations in adult endocrine diseases that evolve with hormone deficit or hypersecretion. In hyperthyroidism, patients develop ventilation disorders, obstructive and central sleep apnea, and pleural collection. The respiratory abnormalities in hyperthyroidism as a result of the hypermetabolic action of thyroid hormones are hyperventilation, myopathy and cardiovascular involvement; recent studies have reported pulmonary arterial hypertension in Graves' disease, as a result of the association of several mechanisms. Thyroid hypertrophy can induce through compression of the upper airways dyspnea, stridor, wheezing and cough. The respiratory disorders in acromegaly are ventilatory dysfunction and sleep apnea, which contribute to an unfavorable evolution of the disease. Respiratory changes in parathyroid, adrenal and reproductive system diseases have been described. Respiratory disorders should be recognized, investigated and monitored by medical practitioners of various specialties (family physicians, internists, endocrinologists, pneumologists, cardiologists). They are frequently severe, causing an unfavorable evolution of the associated endocrine and respiratory disease.

Hyperthyroidism and Complete Atrioventricular Block

Although cardiovascular manifestations in thyroid disorders are frequently encountered in clinical practice, atrioventricular (AV) conduction disorders, especially in hyperthyroidism, are rare. There are some proposed mechanisms for AV blocks in hyperthyroidism but the exact mechanism is still unknown. The authors report 2 cases with thyroid function disorders and complete AV block, and the electrophysiologic characteristics of these 2 patients, and they review and speculate on similar reported cases.

Effects of Arginase Inhibition in Hypertensive Hyperthyroid Rats

BACKGROUND

This study analyzed the effects of chronic administration of N[omega]-hydroxy-nor-l-arginine (nor-NOHA), an inhibitor of arginase, on the hemodynamic, oxidative stress, morphologic, metabolic, and renal manifestations of hyperthyroidism in rats.

METHODS

Four groups of male Wistar rats were used: control, nor-NOHA-treated (10 mg/kg/day), thyroxine (T4)-treated (75 μg/rat/day), and thyroxine- plus nor-NOHA-treated rats. All treatments were maintained for 4 weeks. Body weight, tail systolic blood pressure (SBP), and heart rate (HR) were recorded weekly. Finally, morphologic, metabolic, plasma, and renal variables were measured. Arginase I and II protein abundance and arginase activity were measured in aorta, heart, and kidney.

RESULTS

The T4 group showed increased arginase I and II protein abundance, arginase activity, SBP, HR, plasma nitrates/nitrites (NOx), brainstem and urinary isoprostanes, proteinuria and cardiac and renal hypertrophy in comparison to control rats. In hyperthyroid rats, chronic nor-NOHA prevented the increase in SBP and HR and decreased proteinuria in association with an increase in plasma NOx and a decrease in brainstem and urinary isoprostanes. In normal rats, nor-NOHA treatment did not significantly change any hemodynamic, morphologic, or renal variables. Acute nor-NOHA administration did not affect renal or systemic hemodynamic variables in normal or T4-treated rats.

CONCLUSION

Hyperthyroidism in rats is associated with the increased expression and activity of arginase in aorta, heart, and kidney. Chronic arginase inhibition with nor-NOHA suppresses the characteristic hemodynamic manifestations of hyperthyroidism in association with a reduced oxidative stress. These results indicate an important role for arginase pathway alterations in the cardiovascular and renal abnormalities of hyperthyroidism.

Sexual dimorphism in autonomic changes and in the renin-angiotensin system in the hearts of mice subjected to thyroid hormone-induced cardiac hypertrophy

Based on the relevance of the renin-angiotensin system and the ongoing controversy regarding the role of the sympathetic nervous system in thyroid hormone-induced cardiac hypertrophy, the aim of the present study was to establish whether the putative difference in the degree of cardiac hypertrophy exhibited by males and females might be related to differences in the sympathetic-vagal balance and/or in the cardiac renin-angiotensin system in mice of different genders. Male and female mice (n = 117) were given 0.1 mg kg(-1) of triiodothyronine or normal saline each day for 10 days consecutively. At the end of that period, study of the heart rate variability, spectral analysis and histopathological examination were performed to assess the sympathetic-vagal balance and the diameter of cardiomyocytes. The cardiac levels of angiotensin I and II were also measured. Treatment with triiodothyronine induced a greater degree of cardiac hypertrophy in male (~73%) than in female mice (~42%). This difference was attributed to greater modulation of the sympathetic nervous system and higher levels of angiotensin I and II in male than in female mice. Our data indicate that thyroid hormone-induced cardiac hypertrophy was more intense in male mice due to the synergic effect of the sympathetic nervous system and the cardiac renin-angiotensin system.

World Health Organization group 5 pulmonary hypertension

World Health Organization (WHO) group 5 pulmonary hypertension (PH) entails a heterogeneous group of disorders that may cause PH by unclear and/or multiple mechanisms. In particular, group 5 includes PH caused by hematologic disorders, systemic diseases, metabolic disorders, chronic renal failure, and disorders leading to pulmonary vascular occlusion or compression. This article discusses common pathogenic mechanisms leading to group 5 PH, followed by a detailed overview of epidemiology, pathogenesis, and disease-specific management of the individual group 5 conditions. Off-label use of vasomodulatory therapies, typically indicated for pulmonary arterial hypertension (WHO group 1 PH), in group 5 conditions is also discussed.

Impact of thyroid hormone administration on fluid requirements and hepatic injury markers in hemorrhagic shock due to liver trauma

INTRODUCTION

The aim of the present study was to evaluate the effect of triiodothyronine (T3) administration in a porcine model of hemorrhagic shock due to liver surgery, in terms of hemodynamic stability, acid-base status, and hepatic injury markers.

MATERIALS AND METHODS

Hemorrhagic shock was induced in swine by left lobe liver resection and allowed bleeding to a mean arterial pressure of 35-40 mmHg for 40 min. Animals were randomly assigned into a sham group (n = 5), a fluid-resuscitated group (n = 7), and a fluid plus T3-resuscitated group (n = 7). T3 was given by continuous intravenous infusion from the beginning of the experiment. After the 40 min of shock animals were resuscitated with the aim of restoring mean arterial pressure (±10% from baseline). Resuscitation lasted for 1 hr and then swine were followed for another 460 min (total 6 hr). Blood loss, hamodynamic parameters, fluids administered, acid-base status, and liver enzymes were measured.

RESULTS

Blood loss was similar in both groups. Animals treated with T3 required less fluids than swine resuscitated with crystalloids and colloids only (N/S 0.9%: 1071 ± 189 ml vs. 2429 ± 535 ml, Voluven 6%: 550 ± 96 ml vs. 1000 ± 289 ml, p < .05), plus they were less acidotic at the end of the observing period (7.38 ± 0.08 vs. 7.26 ± 0.12, p < .05). Tachycardia was not associated with T3 administration. Hepatic enzymes did not exhibit differences between groups.

CONCLUSION

Our study demonstrates the beneficial impact of T3 administration during controlled hemorrhagic shock and resuscitation. Animals resuscitated with T3 necessitate less amounts of fluids to maintain hemodynamic stability and acid-base status. Moreover, T3 administration does not seem to aggravate blood loss or harm the hepatic tissue.

Thyroid dysfunction and autoantibodies in early pregnancy are associated with increased risk of gestational diabetes and adverse birth outcomes

CONTEXT

Maternal thyroid dysfunction, especially in early pregnancy, may lead to pregnancy complications and adverse birth outcomes. Few population-based prospective studies have evaluated these effects and results are discrepant.

OBJECTIVE

We examined the association of thyroid function and autoimmunity in early pregnancy with adverse pregnancy and birth outcomes.

SETTING AND PARTICIPANTS

The study used data from the prospective mother-child cohort "Rhea" study in Crete, Greece. A total of 1170 women with singleton pregnancies participated in this analysis. Maternal serum samples in the first trimester of pregnancy were tested for thyroid hormones (TSH, free T(4), and free T(3)) and thyroid antibodies (thyroid peroxidase antibody and thyroglobulin antibody). Multivariable log-Poisson regression models were used adjusting for confounders.

MAIN OUTCOME MEASURES

Outcomes included gestational diabetes, gestational hypertension/preeclampsia, cesarean section, preterm delivery, low birth weight, and small-for-gestational-age neonates.

RESULTS

The combination of high TSH and thyroid autoimmunity in early pregnancy was associated with a 4-fold increased risk for gestational diabetes [relative risk (RR) 4.3, 95% confidence interval (CI) 2.1-8.9)] and a 3-fold increased risk for low birth weight neonates (RR 3.1, 95% CI 1.2-8.0) after adjustment for several confounders. Women positive for thyroid antibodies without elevated TSH levels in early pregnancy were at high risk for spontaneous preterm delivery (RR 1.7, 95% CI 1.1-2.8), whereas the combined effect of high TSH and positive thyroid antibodies did not show an association with preterm birth.

CONCLUSIONS

High TSH levels and thyroid autoimmunity in early pregnancy may detrimentally affect pregnancy and birth outcomes.

The renin-angiotensin system in thyroid disorders and its role in cardiovascular and renal manifestations

Thyroid disorders are among the most common endocrine diseases and affect virtually all physiological systems, with an especially marked impact on cardiovascular and renal systems. This review summarizes the effects of thyroid hormones on the renin-angiotensin system (RAS) and the participation of the RAS in the cardiovascular and renal manifestations of thyroid disorders. Thyroid hormones are important regulators of cardiac and renal mass, vascular function, renal sodium handling, and consequently blood pressure (BP). The RAS acts globally to control cardiovascular and renal functions, while RAS components act systemically and locally in individual organs. Various authors have implicated the systemic and local RAS in the mediation of functional and structural changes in cardiovascular and renal tissues due to abnormal thyroid hormone levels. This review analyzes the influence of thyroid hormones on RAS components and discusses the role of the RAS in BP, cardiac mass, vascular function, and renal abnormalities in thyroid disorders.

Prevalence of echocardiographic criteria for the diagnosis of pulmonary hypertension in patients with Graves' disease: before and after antithyroid treatment

BACKGROUND

Right-sided heart failure with clinical manifestation is only occasionally seen in patients with Graves' disease (GD). Recent studies revealed that pulmonary hypertension (PHT) detected by echocardiography was not rare in patients with GD. We performed this study to investigate the prevalence of PHT in patients with GD before and after antithyroid treatment, and to assess potential mechanisms from the relationship with clinical and echocardiographic features.

SUBJECTS AND METHODS

Serial echocardiographic examinations were performed in 64 patients with newly diagnosed GD before and after antithyroid treatment to measure cardiac factors, such as pulmonary artery systolic pressure (PAPs), cardiac output, total vascular resistance, left ventricular filling pressure and right ventricular (RV) function. PHT was defined as PAPs of at least 35 mmHg.

RESULTS

The prevalence of PHT in untreated GD patients was 44% (28 out of 64 patients). The presence of systemic hypertension was associated with PHT, especially with pulmonary venous hypertension. GD patients with PHT showed reduced RV function represented by higher RV myocardial performance index without difference of pulmonary vascular resistance, RV wall thickness and peak systolic velocity of free wall side of tricuspid annulus. Follow-up echocardiography was performed in 20 out of 28 GD patients with PHT, and PHT disappeared in all except one patient.

CONCLUSION

PHT is a frequent and reversible complication in patients with GD. Our study suggests that PHT in GD may not be related to underlying autoimmune process and increased pulmonary blood flow from thyrotoxicosis might contributes to the pathogenesis of PHT related to GD.

Oral manifestations of thyroid disorders and its management

The thyroid is the major regulator of metabolism and affects all of the bodily functions. Thyroid dysfunction is the second most common glandular disorder of the endocrine system which may rear its head in any system in the body including the mouth. The oral cavity is adversely affected by either an excess or deficiency of these hormones. Before treating a patient who has thyroid disorder, the endocrinologist needs to be familiar with the oral manifestations of thyroid dysfunctions. The patient with a thyroid dysfunction, as well as the patient taking medications for it, requires proper risk management before considering dental treatment by the dentist. Thus, communication of dentist with endocrinologist must be bidirectional, to maintain patient's oral and thyroid health.

Extracorporeal membrane oxygenation rescues thyrotoxicosis-related circulatory collapse

BACKGROUND

Heart failure is one of the best-known complications of thyrotoxicosis. Thyrotoxicosis-induced heart failure sometimes causes circulatory collapse with a high mortality. There is little published information regarding venous-artery mode extracorporeal membrane oxygenation (V-A mode ECMO) to treat circulatory collapse in patients with thyrotoxicosis. Here, we present four patients who received this treatment.

SUMMARY

We present four patients of severe heart failure secondary to severe thyrotoxicosis. All patients suffered from cardiovascular collapse initially. In addition to primary resuscitation and the antithyroid drugs provided, ECMO was applied for temporally hemodynamic support. One patient expired, and the other three patients successfully recovered from heart failure under the support of V-A mode ECMO. The thyroid function also returned to normal range.

CONCLUSION

Patients experiencing heart failure due to severe thyrotoxicosis should be admitted to intensive care unit for close hemodynamic monitor. In addition, mechanical circulatory support such as ECMO should be provided immediately once circulatory collapse occurs.

Hypothyroidism and hypertension

Hypothyroidism has been recognized as a cause of secondary hypertension. Previous studies on the prevalence of hypertension in subjects with hypothyroidism have demonstrated elevated blood pressure values. Increased peripheral vascular resistance and low cardiac output has been suggested to be the possible link between hypothyroidism and diastolic hypertension. The hypothyroid population is characterized by significant volume changes, initiating a volume-dependent, low plasma renin activity mechanism of blood pressure elevation. This article summarizes previous studies on the impact of hypothyroidism on blood pressure and early atherosclerotic process.

Effects of thyroid dysfunction on lipid profile

Thyroid dysfunction has a great impact on lipids as well as a number of other cardiovascular risk factors. Hypothyroidism is relatively common and is associated with an unfavorable effect on lipids. Substitution therapy is beneficial for patients with overt hypothyroidism, improving lipid profile. However, whether subclinical hypothyroidism should be treated or not is a matter of debate. On the other hand, hyperthyroidism can be associated with acquired hypocholesterolemia or unexplained improvement of lipid profile. Overall, thyroid dysfunction should be taken into account when evaluating and treating dyslipidemic patients.

A case of pulmonary arterial hypertension associated with hyperthyroidism, persistent after euthyroidism was obtained

Cardiovascular manifestations in hyperthyroidism occur frequently with various phenotypes. An association between hyperthyroidism and pulmonary arterial hypertension has been reported. In previously reported cases, the hemodynamic and symptomatic recovery of pulmonary arterial hypertension is usually concomitant with achievement of euthyroidism. We report a patient who had pulmonary arterial hypertension associated with Graves' disease, which persisted after euthyroidism was obtained.