Human Mitochondrial Transcription Factor A Reduction and Mitochondrial Dysfunction in Hashimoto’s Hypothyroid Myopathy

Association between physical activity and thyroid function in American adults: a survey from the NHANES database

OBJECTIVE

Physical activity (PA) is closely related to our lives, and the effects of PA on thyroid function have not been elucidated.

METHODS

Using data from the National Health and Nutrition Examination Survey (NHANES) 2007-2012, we included 5877 participants and analyzed the associations of thyroid function with weekly physical activity (PAM, expressed in metabolic equivalents of task) and physical activity time (PAT) in American adults. Univariate and multivariate logistic analyses were used to demonstrate the associations of PAM and PAT with the primary outcome. Linear regression analysis was performed to determine the associations between thyroid biochemical indicators/diseases and PAM/PAT.

RESULTS

Our study revealed noticeable sex differences in daily PA among the participants. The odds ratio of the fourth versus the first quartile of PAM was 3.07 (confidence interval, CI [1.24, 7.58], p = 0.02) for overt hypothyroidism, 3.25 (CI [1.12, 9.45], p = 0.03) for subclinical hyperthyroidism in adult men. PAT in the range of 633-1520 min/week was found to be associated with the occurrence of subclinical hyperthyroidism [p < 0.001, OR (95% CI) = 5.89 (1.85, 18.80)], PAT of the range of > 1520 min/week was found to be associated with the occurrence of overt hypothyroidism [p < 0.001, OR (95% CI) = 8.70 (2.80, 27.07)] and autoimmune thyroiditis (AIT) [p = 0.03, OR (95% CI) = 1.42 (1.03, 1.97)] in adult men. When PAM < 5000 MET*minutes/week or PAT < 1000 min/week, RCS showed an L-shaped curve for TSH and an inverted U-shaped curve for FT4. The changes in FT3 and TT3 in men were linearly positively correlated with PAM and PAT, while TT4 is linearly negatively correlated.

CONCLUSION

The amount of daily physical activity of American adults is strongly associated with changes in thyroid function, including thyroid hormone levels and thyroid diseases. Thyroid hormone levels were varied to a certain extent with changes in PAM and PAT.

Increased Risk of Type 2 Diabetes in Patients With Thyroid Cancer After Thyroidectomy: A Nationwide Cohort Study

CONTEXT

Abnormal thyroid function after thyroidectomy and subsequent thyroid-stimulating hormone suppression can have detrimental effects on glucose homeostasis in patients with thyroid cancer.

OBJECTIVE

To investigate whether thyroidectomy increases the risk of type 2 diabetes in patients with thyroid cancer and to explore the association between levothyroxine dosage and type 2 diabetes risk.

METHODS

A retrospective population-based cohort study using the Korean National Health Insurance database. We included 36 377 thyroid cancer patients without known diabetes who underwent thyroidectomy between 2004 and 2013. Matched subjects with nonthyroid cancer were selected using 1:1 propensity score matching. The main outcome measure was newly developed type 2 diabetes mellitus.

RESULTS

Patients with thyroid cancer who underwent thyroidectomy had a higher risk of developing type 2 diabetes mellitus than the matched controls (hazard ratio [HR] 1.43, 95% CI 1.39-1.47). Among patients with thyroid cancer, when the second quartile group (in terms of the mean levothyroxine dosage; 101-127 μg/day) was considered the reference group, the risk of type 2 diabetes mellitus increased in the first quartile (<101 μg/day; HR 1.45, 95% CI 1.36-1.54) and fourth quartile groups (≥150 μg/day; HR 1.37, 95% CI 1.29-1.45); meanwhile, the risk decreased in the third quartile group (128-149 μg/day; HR 0.91, 95% CI 0.85-0.97).

CONCLUSION

Patients with thyroid cancer who underwent thyroidectomy were more likely to develop type 2 diabetes mellitus than the matched controls. There was a U-shaped dose-dependent relationship between the levothyroxine dosage and type 2 diabetes mellitus risk.

The Effect of Smoking on Mitochondrial Biogenesis in Patients With Graves Ophthalmopathy

PURPOSE

To evaluate the effects of cigarette smoking on oxidative stress (OS) and mitochondrial biogenesis related parameters in patients Graves Ophthalmopathy (GO).

METHODS

Patients with moderate-to-severe GO according to the European Group on Graves Orbitopathy (EUGOGO) criteria were prospectively enrolled in this study. Age- and sex-matched healthy volunteers who applied to outpatient clinic due to refractive problems consisted the control group. Participants were divided into 4 groups based on their diagnosis and smoking status: group 1 (n = 30) smoker GO patients, group 2 (n = 30) nonsmoker GO patients, group 3 (n = 30) smoker healthy controls, and group 4 (n = 30) nonsmoker healthy controls. In the sera, total antioxidant status, total oxidant status and OS index values, peroxisome proliferator-activated receptor-γ coactivator 1-α, mitochondrial transcriptional factor A levels, and paraoxonase-1 enzyme activity were evaluated.

RESULTS

Total oxidant status and OS index values were the highest in group 1 compared to other groups (p = 0.031, p = 0.042; respectively). There was no statistically significant difference in total antioxidant status and peroxisome proliferator-activated receptor-γ coactivator 1α levels among the groups (p = 0.521, p = 0.388; respectively). Paraoxonase-1 enzyme activity was the lowest in group 1 and highest in group 4 (p = 0.024). The levels of mitochondrial transcriptional factor A was the lowest in group 1 compared to other groups (p = 0.012).

CONCLUSIONS

Cigarette smoking in GO patients seems to be a risk factor that increases OS, and therefore, it may have an unfavorable impact on the mitochondrial biogenesis.

The Impact of Mitochondrial Deficiencies in Neuromuscular Diseases

Neuromuscular diseases (NMDs) are a heterogeneous group of acquired or inherited rare disorders caused by injury or dysfunction of the anterior horn cells of the spinal cord (lower motor neurons), peripheral nerves, neuromuscular junctions, or skeletal muscles leading to muscle weakness and waste. Unfortunately, most of them entail serious or even fatal consequences. The prevalence rates among NMDs range between 1 and 10 per 100,000 population, but their rarity and diversity pose difficulties for healthcare and research. Some molecular hallmarks are being explored to elucidate the mechanisms triggering disease, to set the path for further advances. In fact, in the present review we outline the metabolic alterations of NMDs, mainly focusing on the role of mitochondria. The aim of the review is to discuss the mechanisms underlying energy production, oxidative stress generation, cell signaling, autophagy, and inflammation triggered or conditioned by the mitochondria. Briefly, increased levels of inflammation have been linked to reactive oxygen species (ROS) accumulation, which is key in mitochondrial genomic instability and mitochondrial respiratory chain (MRC) dysfunction. ROS burst, impaired autophagy, and increased inflammation are observed in many NMDs. Increasing knowledge of the etiology of NMDs will help to develop better diagnosis and treatments, eventually reducing the health and economic burden of NMDs for patients and healthcare systems.

Fenofibrate monotherapy-induced rhabdomyolysis in a patient with hypothyroidism: A rare case report and literature review

RATIONALE

Fenofibrate is a fibric acid derivative indicated for use in hypertriglyceridemia and mixed dyslipidemia treatment among adults. Rhabdomyolysis is a syndrome characterized by muscle necrosis and the release of intracellular muscle contents into the systemic circulation, which is the most serious and fatal side effect of fenofibrate. The objective of this paper is to discuss fatal side effect of fenofibrate and keep safe medication.

PATIENT CONCERNS

A patient with hypothyroidism who presented with rhabdomyolysis during fenofibrate monotherapy for hypertriglyceridemia was reported.

DIAGNOSES

Fenofibrate Monotherapy Induced Rhabdomyolysis.

INTERVENTIONS

Fenofibrate was stopped. Adequate fluid resuscitation, mannitol diuresis, myocardium protection, hepatoprotection and urine alkalinization with sodium bicarbonate were performed.

OUTCOMES

Blood tests were normal and the patient was good and discharged 2 weeks later.

LESSONS

13 cases associated with fenofibrate monotherapy-induced rhabdomyolysis were reviewed, which had been published in the English literature. The severity of fenofibrate muscle toxicity may be the result of the combination of two rhabdomyolysis enhancers, such as hypothyroidism and female gender. To avoid it, strict clinical and laboratory monitoring should be maintained, particularly hypothyroidism. Patients should be informed of possible potentially irreversible effects after taking fibrates.

The WOMED model of benign thyroid disease: Acquired magnesium deficiency due to physical and psychological stressors relates to dysfunction of oxidative phosphorylation

BACKGROUND

The aim of this study was to discern whether a relation between biochemical parameters, sonography and musculoskeletal data exists in cases of hyperthyroidism and whether they are modifiable through supplementation with selenomethionine and magnesium citrate as well as by acupuncture and manual medicine methods.

RESULTS

A direct correlation between whole blood selenium and serum magnesium was found in subjects without thyroid disease and in menopausal women while it was reversed in cases of thyroid diseases as well as in patients with depression, infection, and in infertile women. Vascularization indices were elevated in cases of newly diagnosed benign thyroid diseases. Musculoskeletal changes i.e. lateral tension and idiopathic moving toes, as well as situations of physical and psychological stress and minor trauma and infection led to an increase of vascularization. Magnesium levels correlated negatively with these two conditions. The supplementation brought a reduction of the vascularization indices and reduced the incidence of idiopathic moving toes. Treatment of lateral tension required manual medicine methods and acupuncture (gastrocnemius). A small subgroup of patients showed a further reduction of hyper-vascularization after receiving coenzyme Q10.

CONCLUSIONS

We interpret the elevated thyroid vascularization and low magnesium levels as signs of an inflammatory process related to the musculoskeletal changes. Improvement of thyroid function and morphology can be achieved after correcting the influence of stressors together with the supplementation regime. We hypothesize that the central biochemical event in thyroid disease is that of an acquired, altered mitochondrial function due to deficiency of magnesium, selenium, and coenzyme Q10.

Impact of overt and subclinical hypothyroidism on exercise tolerance: a systematic review

PURPOSE

This systematic review describes the state of the art of the impact of hypothyroidism on exercise tolerance and physical performance capacity in untreated and treated patients with hypothyroidism.

METHOD

A systematic computer-aided search was conducted using biomedical databases. Relevant studies in English, German, and Dutch, published from the earliest date of each database up to December 2012, were identified.

RESULTS

Out of 116 studies, a total of 38 studies with 1,379 patients fulfilled the inclusion criteria. These studies emphasize the multifactorial causes of exercise intolerance in untreated patients by the impact of limitations in different functional systems, with cardiovascular, cardiopulmonary, musculoskeletal, neuromuscular, and cellular metabolic systems acting in concert. Moreover, the studies affirm that exercise intolerance in patients is not always reversible during adequate hormone replacement therapy. As a consequence, despite a defined euthyroid status, there remains a significant group of treated patients with persistent complaints related to exercise intolerance who are suffering from limitations in daily and sport activities, as well as an impaired quality of life. An explanation for this phenomenon is lacking. Only 2 studies investigated the effects of a physical training program, and they showed inconsistent effects on the performance capacity in untreated patients with subclinical hypothyroidism.

CONCLUSIONS

A limited body of knowledge exists concerning exercise tolerance in treated patients with hypothyroidism, and there is an insufficient amount of quantitative studies on the effects of a physical training program. To enhance exercise and sports participation for this specific group, more research in this forgotten area is warranted.

Pulmonary oxygen uptake kinetics during exercise in subclinical hypothyroidism

BACKGROUND

Patients with subclinical hypothyroidism (SCH) have lower exercise tolerance, but the impact on oxygen uptake (VO2) kinetics is unknown. This study evaluated VO2 kinetics during and after a constant load submaximal exercise in SCH.

METHODS

The study included 19 women with SCH (thyrotropin (TSH)=6.87±2.88 μIU/mL, free thyroxine (fT4)=0.97±0.15 ng/dL) and 19 controls (TSH=2.29±0.86 μIU/mL, T4=0.99±0.11 ng/dL) aged between 20 and 55 years. Ergospirometry exercise testing was performed for six minutes with a constant load of 50 W, followed by six minutes of passive recovery. The VO2 kinetics was quantified by the mean response time (MRT), which is the exponential time constant and approximates the time needed to reach 63% of change in VO2 (ΔVO2). The O2 deficit-energy supplied by anaerobic metabolism at the onset of exercise-and O2 debit-extra energy demand during the recovery period-were calculated by the formula MRT×ΔVO2. Values are mean±standard deviation.

RESULTS

In the rest-exercise transition, patients with SCH showed slower VO2 kinetics (MRT=47±8 sec vs. 40±6 sec, p=0.004) and a higher oxygen deficit (580±102 mL vs. 477±95 mL, p=0.003) than controls respectively. In the exercise-recovery transition, patients with SCH also showed slower VO2 kinetics (MRT=54±6 sec vs. 44±6 sec, p=0.001) and a higher oxygen debit (679±105 mL vs. 572±104 mL, p=0.003). The VO2 kinetics showed a significant correlation with TSH (p<0.05).

CONCLUSIONS

This study demonstrates that women with SCH have the slowest VO2 kinetics in the onset and recovery of a constant-load submaximal exercise and highlights that this impairment is already manifest in the early stage of the disease.

Subclinical thyroid dysfunction and functional capacity among elderly

BACKGROUND

Subclinical thyroid dysfunction is common among older people and has been associated with decreased functional capacity but with conflicting data. The aim of this study was to assess the association between subclinical thyroid dysfunction and functional capacity in an elderly population.

METHODS

We included 5182 participants with a mean age of 75.2 years from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER). Self-reported functional capacity was assessed using the Barthel Index (BI) and the Instrumental Activities of Daily Living (IADL) scores at baseline and during follow-up. Participants with subclinical hyperthyroidism (n=65) and subclinical hypothyroidism (n=173) were compared to euthyroid participants (n=4944). The association between persistent subclinical thyroid dysfunction and functional capacity and decline was also investigated.

RESULTS

At baseline, compared to euthyroid participants (BI 19.73±SE 0.06; IADL 13.52±0.02), there was no difference in functional capacity for participants with subclinical hyperthyroidism (BI 19.60±0.09; IADL 13.51±0.12, p>0.05) or subclinical hypothyroidism (BI 19.82±0.06; IADL 13.55±0.08, p>0.05). Over a mean 3.2-year follow-up period, there was no association between thyroid function and annual decline of either BI or IADL (p>0.05). No association was found between persistent subclinical thyroid dysfunction and functional capacity at baseline or during follow-up (p>0.05). Results were similar after excluding participants with a maximum BI and/or IADL score at baseline.

CONCLUSION

Among well-functioning community-dwelling elderly, we found no evidence that subclinical thyroid dysfunction contributes to decreased functional capacity.

Thyroid disease and the nervous system

Thyroid disorders are common in the general population and in hospitalized patients. Thyroid disease may present first with neurological complications or else may occur concurrently in patients suffering other neurological disorders, particularly those with an autoimmune etiology. For this reason neurologists will commonly encounter patients with thyroid disease. This chapter provides an overview of the neurological complications and associations of disorders of the thyroid gland. Particular emphasis is placed on conditions such as thyrotoxic periodic paralysis and myxedema coma in which the underlying thyroid disorder may be occult leading to a first, often emergency, presentation to a neurologist. Information about clinical features, diagnosis, pathogenesis, therapy, and prognosis is provided. Emphasis is placed on those aspects most likely to be relevant to the practicing neurologist and the interested reader is directed to references to good, recent review articles for further information.

A myriad of pathways to NASH

Nonalcoholic steatohepatitis (NASH) is defined histopathologically by the presence of macrovesicular steatosis, cellular ballooning, and inflammation. NASH represents a complex multifactorial disease that typically occurs within the context of the metabolic syndrome. NASH lacks homogeneity, and other forms of NASH can present atypically. Less than 50% of patients with NASH respond to pharmacologic treatment, which speaks to this heterogeneity. The authors discuss drugs, disease entities, and nutritional states that can cause or exacerbate underlying NASH indirectly through worsening insulin resistance or directly by interfering with lipid metabolism, promoting oxidative injury, or activating inflammatory pathways.

Prevalence of hypothyroidism in nonalcoholic fatty liver disease

BACKGROUND

A possible association between nonalcoholic fatty liver disease (NAFLD) and hypothyroidism has been suggested. The recognized link between hypothyroidism and elements of the metabolic syndrome may explain this association.

AIM

The purpose of this study was to determine the prevalence of hypothyroidism in a cohort of patients with NAFLD and analyze the potential factors associated with hypothyroidism in this patient population.

METHODS

Two hundred forty-six patients with biopsy-proven NAFLD attending hepatology clinics at the Cleveland Clinic between October 2006 and June 2009, and 430 age-, gender-, race- and BMI-matched control subjects seen in the general internal medicine clinic were included. Patients with a clinical diagnosis of hypothyroidism who were on thyroid replacement therapy were considered to be hypothyroid.

RESULTS

Hypothyroidism was more frequent among patients with NAFLD (21% vs. 9.5%; P < 0.01) compared to controls, and was higher in NASH patients than NAFLD patients without NASH (25% vs. 12.8%, P = 0.03). Subjects with hypothyroidism were 2.1 (95% CI 1.1-3.9, P = 0.02) and 3.8 (95% CI 2-6.9, P < 0.001) times more likely to have NAFLD and NASH, respectively. By multivariate analysis, female gender (P < 0.001) and increased BMI (P = 0.03) were associated with hypothyroidism. NAFLD subjects who reported mild alcohol consumption were less likely to have hypothyroidism compared to those who reported complete abstinence (OR 0.37, P = 0.008).

CONCLUSIONS

A higher prevalence of hypothyroidism was demonstrated in patients with NAFLD compared to controls. Among subjects with NALFD, female gender, increased BMI and history of abstinence from alcohol were associated with hypothyroidism. Patients with hypothyroidism were also more likely to have NASH.

Kocher-Debré-Sémélaigne syndrome with pericardial effusion

Kocher-Debré-Sémélaigne syndrome (KDSS) is a rare association of muscular pseudohypertrophy and hypothyroidism in children. We report an 11-year-old female child with hypothyroidism and limb muscle pseudohypertrophy with pericardial effusion. The patient presented with hypertrichosis only. She had dull facies and marked hypertrophy of both calves and cervical muscles. Pericardial effusion was confirmed on investigations. Muscle pseudohypertrophy was a striking feature, and hypothyroidism was confirmed on thyroid studies. Pericardial effusion is known in hypothyroidism but has been very rarely reported with KDSS.

Fenofibrate-induced rhabdomyolysis in a patient with chronic kidney disease: an unusual presenting feature of hypothyroidism

Clinical and most often moderate skeletal muscle involvement is a frequent problem in adults with hypothyroidism, and includes a number of different manifestations. Severe involvement with rhabdomyolysis, however, is very rare, and only a few cases have been reported to date, most of them with an additional factor of muscle injury. We described a patient with stage 3 chronic kidney disease who presented with rhabdomyolysis while taking fenofibrate, and was found to have hypothyroidism. We also highlighted the importance of excluding the diagnosis of thyroid dysfunction before treatment with lipid-lowering agents.

Improvements in insulin sensitivity are blunted by subclinical hypothyroidism

PURPOSE

Exercise- and weight loss-induced improvements in insulin resistance (IR) are variable; some individuals experience robust enhancements in insulin sensitivity, whereas others do not. Thyroid hormone status is related to IR, but it is not clear whether subclinical hypothyroidism may help to explain the variability in improvements in IR with diet and exercise. The purpose of this study was to examine whether thyroid hormone status is related to the improvement in insulin sensitivity and physical fitness after weight loss and exercise training.

METHODS

By retrospective nested case-control analysis, eight subclinical hypothyroid (sHT) subjects and eight matched euthyroid controls underwent a euglycemic hyperinsulinemic clamp and peak oxygen uptake test, before and after a 16-wk program of moderate aerobic exercise combined with diet-induced weight loss. All subjects were middle-aged (57.3 +/- 3.3 yr), were overweight to obese (body mass index = 33.1 +/- 0.8 kg m(-2)), and had impaired glucose tolerance.

RESULTS

The improvement in insulin sensitivity was significantly lower (P < 0.05) in the sHT group than in the euthyroid group. Both groups performed similar amounts of regular exercise and lost a significant amount of body weight during the intervention. VO(2peak) tended to improve in the euthyroid group but not in the sHT group.

CONCLUSION

Subclinical hypothyroidism may interfere with beneficial adaptations on muscle metabolism and physical fitness that typically occur with weight loss and increased physical activity. These results may have significant clinical implications because of the high prevalence of both hypothyroidism and insulin resistance in the aging population.

Mitochondrial biogenesis restores oxidative metabolism during Staphylococcus aureus sepsis

RATIONALE

The extent, timing, and significance of mitochondrial injury and recovery in bacterial sepsis are poorly characterized, although oxidative and nitrosative mitochondrial damage have been implicated in the development of organ failure.

OBJECTIVES

To define the relationships between mitochondrial biogenesis, oxidative metabolism, and recovery from Staphylococcus aureus sepsis.

METHODS

We developed a murine model of fibrin clot peritonitis, using S. aureus. The model yielded dose-dependent decreases in survival and resting energy expenditure, allowing us to study recovery from sublethal sepsis.

MEASUREMENTS AND MAIN RESULTS

Peritonitis caused by 10(6) colony-forming units of S. aureus induced a low tumor necrosis factor-alpha state and minimal hepatic cell death, but activated prosurvival protein kinase A, B, and C sequentially over 3 days. Basal metabolism by indirect calorimetry was depressed because of selective mitochondrial oxidative stress and subsequent loss of mitochondrial DNA copy number. During recovery, mitochondrial biogenesis was strongly activated by regulated expression of the requisite nuclear respiratory factors 1 and 2 and the coactivator peroxisome proliferator-activated receptor gamma coactivator-1alpha, as well as by repression of the biogenesis suppressor nuclear receptor interacting protein-140. Biogenesis reconstituted mitochondrial DNA copy number and transcription, and restored basal metabolism without significant hepatocellular proliferation. These events dramatically increased hepatic mitochondrial density in transgenic mice expressing mitochondrially targeted green fluorescent protein.

CONCLUSIONS

This is the first demonstration that mitochondrial biogenesis restores oxidative metabolism in bacterial sepsis and is therefore an early and important prosurvival factor.