Neuromuscular findings in thyroid dysfunction: a prospective clinical and electrodiagnostic study

Are resting metabolic rate and clinical symptoms affected by variation of serum thyroid stimulating hormone levels within the normal range in healthy and women with hypothyroidism? A case-control study

BACKGROUND

It is unclear whether variation in thyroid stimulating hormone (TSH) levels within the reference range affect energy expenditure and clinical symptoms and even within the normal range of TSH levels, resting energy expenditure may alter. The aim of the present study was to determine whether treated hypothyroid subjects and healthy subjects with a low-normal TSH range (0.3-2.3 mIU/L) have better clinical outcomes and increased energy expenditure than those with a high-normal TSH range (2.3-4.3 mIU/L).

METHODS

This was a case-control study of 160 overweight/obese women with TSH levels across the reference range of 0.3-4.3 mU/l. Subjects were paired in four groups: healthy subjects with low-normal target TSH (n = 40), healthy subjects with high-normal target TSH (n = 40), subjects with treated hypothyroidism with low-normal target TSH (n = 40), and subjects with treated hypothyroidism with high-normal target TSH (n = 40). Resting energy expenditure (RMR), dietary intake, body composition, physical activity, and biochemical markers were assessed.

RESULTS

Subjects with low-normal (≤2.3 mU/L) and high-normal (>2.3 mU/L) TSH levels did not differ in terms of RMR, serum T3 levels, and clinical symptoms except fatigue (P = 0.013). However, serum fT4 levels were found to be significantly different between the study groups (P = 0.002). Serum fT4 concentration was the highest in subjects with treated hypothyroidism with low-normal target TSH.

CONCLUSION

Variation in serum TSH levels within the reference range did not significantly affect REE and clinical symptoms except fatigue in healthy and women with hypothyroidism.

Impaired autonomic function and somatosensory disturbance in patients with treated autoimmune thyroiditis

Despite treatment with levothyroxine, hypothyroidism and autoimmune thyroiditis (AIT) may be associated with reduced quality of life (QoL), an enigmatic condition referred to as "syndrome T". Peripheral neuropathy, described in untreated thyroid disease, could be a contributing mechanism. We analysed autonomic and somatosensory function in 29 patients with AIT and treated hypothyroidism and 27 healthy volunteers. They underwent heart rate variability (HRV) analysis and quantitative sensory testing (n = 28), comprising 13 parameters of small and large nerve fibre function and pain thresholds. Autonomic cardiovascular function was assessed in rest, deep respiration and orthostasis. Additionally, biomarkers for autoimmunity and thyroid function were measured. Anxiety, depression and QoL were assessed using validated questionnaires. 36% of the patients showed at least one sign of somatosensory small or large fibre dysfunction. 57% presented with mild hyperalgesia to at least one stimulus. Several markers of autonomic function and some detection thresholds were related to the antibody titres. Anxiety, depression scores and QoL correlated to antibody titres and HRV measures. Autonomic and somatosensory dysfunction indicate that in treated hypothyroidism and AIT a subgroup of patients suffers from neuropathic symptoms leading to impaired QoL. Additionally, mild hyperalgesia as a possible sensitisation phenomenon should be considered a target for symptomatic treatment.

Axonal excitability as an early biomarker of nerve involvement in hereditary transthyretin amyloidosis

OBJECTIVES

The treatment of hereditary transthyretin amyloidosis polyneuropathy (ATTRv-PN) has been revolutionised by genetic therapies, with dramatic improvements in patient outcomes. Whilst the optimal timing of treatment initiation remains unknown, early treatment is desirable. Consequently, the aim of the study was to develop biomarkers of early nerve dysfunction in ATTRv-PN.

METHODS

Ulnar motor and sensory axonal excitability studies were prospectively undertaken on 22 patients with pathogenic hereditary transthyretin amyloid (ATTRv) gene variants, 12 with large fibre neuropathy (LF+) and 10 without (LF-), with results compared to age- and sex-matched healthy controls.

RESULTS

In motor axons we identified a continuum of change from healthy controls, to LF- and LF+ ATTRv with progressive reduction in hyperpolarising threshold electrotonus (TEh40(10-20 ms): p = 0.04, TEh40(20-40 ms): p = 0.01 and TEh40(90-10 ms): p = 0.01), suggestive of membrane depolarisation. In sensory axons lower levels of subexcitability were observed on single (SubEx) and double pulse (SubEx2) recovery cycle testing in LF+ (SubEx: p = 0.015, SubEx2: p = 0.015, RC(2-1): p = 0.04) suggesting reduced nodal slow potassium conductance, which promotes sensory hyperexcitability, paraesthesia and pain. There were no differences in sensory or motor excitability parameters when comparing different ATTRv variants.

CONCLUSIONS

These progressive changes seen across the disease spectrum in ATTRv-PN suggest that axonal excitability has utility to identify early and progressive nerve dysfunction in ATTRv, regardless of genotype.

SIGNIFICANCE

Axonal excitability is a promising early biomarker of nerve dysfunction in ATTRv-PN.

High risk and low prevalence diseases: Guillain-Barré syndrome

INTRODUCTION

Guillain-Barré syndrome (GBS) is a rare but serious condition that carries with it a high rate of morbidity and mortality.

OBJECTIVE

This review highlights the pearls and pitfalls of GBS, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence.

DISCUSSION

GBS is a rare immune-mediated neurologic disorder with peripheral nerve injury. It most commonly presents weeks after a bacterial or viral infection, though there are a variety of associated inciting events. The diagnosis is challenging and often subtle, as only 25-30% of patients are diagnosed on their initial healthcare visit. Clinicians should consider GBS in patients with progressive ascending weakness involving the lower extremities associated with hyporeflexia, but the cranial nerves, respiratory system, and autonomic system may be involved. While the ED diagnosis should be based on clinical assessment, further evaluation includes laboratory testing, cerebrospinal fluid (CSF) analysis, and potentially neuroimaging. Not all patients demonstrate albumino-cytological dissociation on CSF testing. Several criteria exist to assist with diagnosis, including the National Institute of Neurological Disorders and Stroke criteria and the Brighton criteria. Management focuses first on assessment of the patient's hemodynamic and respiratory status, which may require emergent intervention. Significant fluctuations in heart rate and blood pressure may occur, and respiratory muscle weakness may result in the need for airway protection. Neurology consultation is recommended, and definitive treatment includes PLEX or IVIG.

CONCLUSIONS

An understanding of GBS can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

Myopathies of endocrine origin: A review for physicians

Myopathies are a common manifestation of endocrine disorders. Endocrine myopathies are often overlooked while considering differential diagnoses in patients with musculoskeletal symptoms. The hindrance to mobility and the musculoskeletal discomfort owing to these myopathies are important causes of disability and depreciated quality of life in these patients. Endocrine myopathies occur due to the effects of endogenous or iatrogenic hormonal imbalance on skeletal muscle protein and glucose metabolism, disrupting the excitation-contraction coupling. Abnormalities of the pituitary, thyroid, parathyroid, adrenal, and gonadal hormones have all been associated with myopathies and musculoskeletal symptoms. Endocrine myopathies can either be the complication of a secondary endocrine disorder or a presenting symptom of a missed underlying disorder. Therefore, an underlying endocrine abnormality must always be excluded in all patients with musculoskeletal symptoms. This review presents a compilation of various endocrine myopathies, their etiopathogenesis, clinical presentation, diagnostic modalities, and treatment protocols.

Atypical presentations of primary acquired hypothyroidism - a case series

Primary acquired hypothyroidism in children manifests with a myriad of clinical presentations. Clinical features can be insidious in nature, often under the guise of non-specific presentations to other subspecialties prior to referral to the endocrinologist. Growth failure is a hallmark feature in these children alongside their presenting clinical symptomology which needs to be identified through detailed history, physical examination and analysis of the growth charts. In this case series, we discuss 5 atypical presentations of acquired primary hypothyroidism with multisystemic involvement, including musculoskeletal, hepatobiliary, gynaecological and haematological manifestations. This is of importance as untreated hypothyroidism leads to fatigue, decreased physical activity, suboptimal height gain, disordered puberty and poor neurocognitive development in children with long term detrimental outcomes.

Hoffmann's syndrome in the differential work-up of myopathic complaints: a case report

BACKGROUND

Hoffmann's syndrome is a rare form of hypothyroid myopathy in adults, which is mainly characterized by muscular weakness and muscular pseudohypertrophy.

CASE PRESENTATION

We report about a 61-year-old Western European man with myalgia, myxedema and pseudohypertrophy of the calf muscles. Laboratory tests revealed significantly elevated thyroid stimulating hormone (TSH) and creatine kinase (CK). Muscle MRI showed muscular hypertrophy of the lower limbs, but no signs of myositis or myopathy (no gadolinium enhancement, no edema, no fatty degeneration). In addition, electromyography (EMG) detected spontaneous activity. After the beginning of thyroxin-therapy it took six months until the muscle weakness improved and the myalgia regressed.

CONCLUSIONS

Here, we focus on diagnostic routines and typical findings to differentiate Hoffmann's syndrome from other myopathies. Clinical hallmarks of Hoffmann's syndrome are pseudohypertrophy and weakness of the calf muscles in combination with elevated CK and elevated TSH. EMG is well suited to detect the involvement of the muscles and muscle MRI helps to differentiate it from other myopathies. Hoffmann's syndrome is a rare myopathy due to hypothyroidism and plays a role in the differential diagnosis of myopathic complaints even if hypothyroidism has not been detected before.

Relationship between Euthyroidism and Muscle Mass and Strength: A Systematic Review

Thyroid hormones play a crucial role in skeletal muscle development, suggesting that thyroid function may influence muscle mass and muscle strength, which are both fundamental health-related indicators of several age-related consequences. However, whether there is a relationship between thyroid hormones, muscle mass, and muscle strength in individuals without thyroid dysfunctions is still unknown. Therefore, this systematic review aims to investigate whether thyroid hormones are related to muscle mass and strength parameters in euthyroid individuals. Three databases were searched (PubMed, Scopus, Web of Science) up to February 14, 2022, for peer-reviewed papers published in English. The search results were conducted independently by two different reviewers. The review included 13 studies with a total of 241,044 participants. All studies were observational: twelve studies measured thyroid stimulating hormone, ten and thirteen studies measured free triiodothyronine and free thyroxine, four studies analyzed the thyroid hormone ratio. The assessment methods for muscle mass were computed tomography, dual-energy X-ray absorptiometry and bioimpedance analysis, whereas hand dynamometer for muscle strength. Low levels within the normal range of free triiodothyronine, high levels within the normal range of free thyroxine, and lower thyroid hormone ratio may contribute to a reduced muscle function, which seems more evident in older males.

Pathogenic SCN5A Mutation and Thyrotoxicosis-Related Neurological Syndrome: Casual or Causal Relationship?

BACKGROUND

Various neurologic complications of hyperthyroidism are reported, and most of these complications are reversible with the amelioration of thyrotoxicosis. We report a previously undescribed concurrence of hyperthyroid-associated exercise-induced myalgia and stiffness, pyramidal tract dysfunction, and myoclonic movements that make an initial clinical diagnosis difficult.

CASE PRESENTATION

A 17-year-old male was hospitalized in the department of neurology, presenting with a 4-year history of severe exercise-induced myalgia and stiffness, weakness of lower limbs, and myoclonic movements. Laboratory investigations unexpectedly revealed hyperthyroidism. MRI of the brain and spine, electrophysiology, and whole exome sequencing were also performed. Antithyroid therapy led to marked improvement of neurologic symptoms, accompanied by a significant improvement of the time-dependent decline in compound muscle action potentials (CMAP) amplitudes after exercise and normalization of the prolonged QTc interval. Genetic analysis identified a rare variant in SCN5A.

CONCLUSION

This case report provides important insights into the relationship between hyperthyroidism and neurologic/cardiac complications, particularly in those with a genetic predisposition. SCN5A mutation possibly plays a role in the complex neurological syndrome associated with hyperthyroidism. Further studies are warranted to better understand the underlying mechanisms and potential therapeutic options for these complex conditions.

An atypical presentation of hypothyroidism with extremely exaggerated functional impairment

Key Clinical Message

Myopathy-related symptoms are rare manifestations of hypothyroidism. Clinicians should consider hypothyroid myopathy as one of the possible diagnoses for patients with proximal weaknesses.

Abstract

Myopathy-related symptoms are rare manifestations of hypothyroidism. Clinicians should consider hypothyroid myopathy as one of the possible diagnoses for patients with proximal weaknesses. We report a 34-year-old woman, presenting with a new atypical musculoskeletal manifestation of hypothyroidism mimicking polymyositis.

Examining Body Fat Percentage, Galvanic Skin Response, and Muscle Grip Strength in Female Hypothyroid Patients

Background The thyroid gland is an indispensable organ exerting control over the activity of multiple organ systems including the autonomic nervous system. This study attempted to monitor the variations in autonomic function parameters such as galvanic skin response (GSR) and muscle grip strength (HGS) in conjunction with changes in body fat percentage (BFP). Methodology This case-control study was conducted among 40 female hypothyroid patients as cases and 40 age-matched female healthy volunteers as controls. Anthropometric data were collected using standard techniques. GSR and HGS were measured using Equivital Sensory Electronic Module and Grip Force Transducer, respectively. Data extraction and analysis were done using the LabChart software. Results The mean age of the 40 female hypothyroid patients was 30.14 ± 5.91 years, whereas the mean age of the female controls was 29.37 ± 6.59 years. The waist circumference of cases was 85.81 ± 10.39 cm while that of controls was 80.90 ± 11.18 cm. The BFP of cases was 35.38% ± 6.74% while that of controls was 31.72% ± 5.63%. The GSR amplitude showed a significant difference between hypothyroid and healthy volunteers with values of 1.34 ± 1.14 μS and 2.40 ± 1.86 μS, respectively. The HGS indices showed no significant difference between the two groups. A statistically negative correlation was noted between BFP and GSR amplitude (-0.32), whereas a positive correlation was noted between BFP and mean handgrip strength (0.31) in hypothyroid patients. Conclusions The changes in BFP and autonomic function through GSR and HGS were evaluated in female hypothyroid patients with respect to healthy females. The interrelationship between anthropometry and autonomic function was also explored in this study. The findings of this study can augment prognosis in patients and ensure timely corrective treatment for improving quality of life.

Choked: A Case Report of Oculopharyngeal Muscular Dystrophy Mimicking Hypothyroidism From the Philippines

Oculopharyngeal muscular dystrophy (OPMD) is a late-onset myopathic genetic disorder characterized by chronic progressive dysphagia and ptosis with or without proximal limb weakness. It is most often caused by an abnormal alanine-encoding (GCN) trinucleotide repeat expansion in the first exon of the poly(A)-binding protein nuclear 1 (PABPN1) gene. Patients with hypothyroidism may similarly report bilateral ptosis, dysphagia, and limb weakness. Here, we report the case of a 65-year-old Austrian female with hypothyroidism living in the Philippines who presented with gradually progressive ptosis, dysphagia, and intermittent choking episodes. No known relatives had similar symptoms. Physical examination showed bilateral symmetric ptosis, good cough reflex, and good limb muscle strength. Electromyographic studies of facial and laryngeal muscles were found to be normal. Thyroid evaluation showed biochemically hyperthyroid status while taking Levothyroxine. With a clinical suspicion for genetic progressive myopathy, we considered OPMD. Genetic testing revealed abnormal expansion of GCN trinucleotide repeats in the PABPN1 gene. We describe the first reported case of OPMD with detected PABPN1 gene expansion in the Philippines simulating hypothyroidism symptoms, suggesting possible points for misidentification and underdiagnosis of OPMD in developing countries.

Neurologic Complications of Endocrine Disorders

OBJECTIVE

This article provides an overview of the neurologic complications of the most prevalent endocrine disorders in adults with an emphasis on relevant neurologic symptoms, signs, and laboratory and neuroimaging findings.

LATEST DEVELOPMENTS

Although the mechanisms of many of the neurologic complications discussed here remain unclear, our understanding of the impacts of diabetes and hypothyroidism on the nervous system and muscle, including complications of rapid correction of chronic hyperglycemia, has advanced in recent years. Recent large studies have not demonstrated a convincing association between subclinical or overt hypothyroidism and cognitive decline.

ESSENTIAL POINTS

Neurologists must become familiar with the neurologic complications of endocrine disorders not only because they are common and treatable (and often reversible) but also because they may be iatrogenic, as is the case with adrenal insufficiency in the setting of long-term corticosteroid therapy.

Age-related variation in thyroid function - a narrative review highlighting important implications for research and clinical practice

BACKGROUND

Thyroid hormones are key determinants of health and well-being. Normal thyroid function is defined according to the standard 95% confidence interval of the disease-free population. Such standard laboratory reference intervals are widely applied in research and clinical practice, irrespective of age. However, thyroid hormones vary with age and current reference intervals may not be appropriate across all age groups. In this review, we summarize the recent literature on age-related variation in thyroid function and discuss important implications of such variation for research and clinical practice.

MAIN TEXT

There is now substantial evidence that normal thyroid status changes with age throughout the course of life. Thyroid stimulating hormone (TSH) concentrations are higher at the extremes of life and show a U-shaped longitudinal trend in iodine sufficient Caucasian populations. Free triiodothyronine (FT3) levels fall with age and appear to play a role in pubertal development, during which it shows a strong relationship with fat mass. Furthermore, the aging process exerts differential effects on the health consequences of thyroid hormone variations. Older individuals with declining thyroid function appear to have survival advantages compared to individuals with normal or high-normal thyroid function. In contrast younger or middle-aged individuals with low-normal thyroid function suffer an increased risk of adverse cardiovascular and metabolic outcomes while those with high-normal function have adverse bone outcomes including osteoporosis and fractures.

CONCLUSION

Thyroid hormone reference intervals have differential effects across age groups. Current reference ranges could potentially lead to inappropriate treatment in older individuals but on the other hand could result in missed opportunities for risk factor modification in the younger and middle-aged groups. Further studies are now needed to determine the validity of age-appropriate reference intervals and to understand the impact of thyroid hormone variations in younger individuals.

THYROTOXICOSIS AND ITS RELATION TO SARCOPENIA, MUSCLE STRENGTH, MUSCLE MASS AND PHYSICAL PERFORMANCE

Background

Sarcopenia is a syndrome, considered one of the main risk factors for morbidity and mortality among adults. Thyrotoxicosis may contribute to its development.

Aim

To assess the physical well-being among women with thyrotoxicosis and to determine the risk of sarcopenia among them; 13 women over 40 years of age with thyrotoxicosis took part in this study.

Materials and Methods

Grip strength was used to assess muscle strength. Appendicular skeletal muscle mass, adjusted for body size was used to asses muscle quantity. Physical performance was measured by gait speed test. We divided women in groups: group A - patients with newly diagnosed thyrotoxicosis and group B - patients who had started treatment.

Results

The values of muscle strength, muscle mass and gait speed were lower in group A compared to group B. Three of the patients in group A were diagnosed with severe sarcopenia. Thus the frequency of sarcopenia was 50% in this group. None of the women in group B met the criteria for sarcopenia.Despite the small number of women in this study, we can conclude that untreated thyrotoxicosis is a risk factor for decreased muscle strength, quantity and physical performance and could cause secondary sarcopenia.

A Rare Case of Hypothyroidism-Induced Rhabdomyolysis

Rhabdomyolysis is a condition caused by muscle breakdown. It can be usually associated with pain, weakness, and elevated creatinine kinase levels on laboratory testing. There are various triggers, some of which can include trauma, dehydration, infections, and, as in this case, autoimmune disorders. Here, we present a case of a patient with worsening muscle pain who was found to have elevated creatinine kinase levels and undiagnosed hypothyroidism, with symptoms improving with intravenous hydration and thyroid supplementation.

Muskelzuckungen und Muskelkrämpfe – Differenzialdiagnosen und elektrophysiologische Diagnostik

Muskelzuckungen und -krämpfe sind Beschwerden, die vom harmlosen Symptom bis hin zu Symptomen einer schwerwiegenden neurologischen Erkrankung reichen können. Eine ausführliche Anamnese, gründliche neurologische Untersuchung und elektrophysiologische Untersuchungen ermöglichen die Unterscheidung der verschiedenen Ätiologien. In diesem Artikel werden verschiedene Ursachen unter Berücksichtigung deren Definition, der elektrophysiologisch zugrunde liegenden Phänomene und deren differenzialdiagnostischer Einordnung dargestellt.

Thyroid Disorders and Movement Disorders-A Systematic Review

Background

There is overlap between movement disorders and neuroendocrine abnormalities.

Objectives and methods

To provide a systematic review on the association of thyroid dysfunction and movement disorders. Thyroid physiological function and classical thyroid disorders highlighting typical and atypical manifestations including movement disorders, as well as diagnostic procedures, and treatments are discussed.

Results

Hypothyroidism may be associated with hypokinetic and hyperkinetic disorders. There is debate whether their concomitance reflects a causal link, is coincidence, or the result of one unmasking the other. Hypothyroidism-associated parkinsonism may resemble idiopathic Parkinson's disease. Hypothyroidism-associated hyperkinetic disorders mainly occur in the context of steroid-responsive encephalopathy with autoimmune thyroiditis, that is, Hashimoto disease, mostly manifesting with tremor, myoclonus, and ataxia present in 28-80%, 42-65% and 33-65% in larger series. Congenital hypothyroidism manifesting with movement disorders, mostly chorea and dystonia, due to Mendelian genetic disease are rare.Hyperthyroidism on the other hand mostly manifests with hyperkinetic movement disorders, typically tremor (present in three quarters of patients). Chorea (present in about 2% of hyperthyroid patients), dystonia, myoclonus, ataxia and paroxysmal movement disorders, as well as parkinsonism have also been reported, with correlation between movement intensity and thyroid hormone levels.On a group level, studies on the role of thyroid dysfunction as a risk factor for the development of PD remain non-conclusive.

Conclusions

In view of the treatability of movement disorders associated with thyroid disease, accurate diagnosis is important. The pathophysiology remains poorly understood. More detailed case documentation and systematic studies, along with experimental studies are needed.

Role of tubulin post-translational modifications in peripheral neuropathy

Peripheral neuropathy is a common disorder that results from nerve damage in the periphery. The degeneration of sensory axon terminals leads to changes or loss of sensory functions, often manifesting as debilitating pain, weakness, numbness, tingling, and disability. The pathogenesis of most peripheral neuropathies remains to be fully elucidated. Cumulative evidence from both early and recent studies indicates that tubulin damage may provide a common underlying mechanism of axonal injury in various peripheral neuropathies. In particular, tubulin post-translational modifications have been recently implicated in both toxic and inherited forms of peripheral neuropathy through regulation of axonal transport and mitochondria dynamics. This knowledge forms a new area of investigation with the potential for developing therapeutic strategies to prevent or delay peripheral neuropathy by restoring tubulin homeostasis.

The effect of thyroid hormone therapy on muscle function, strength and mass in older adults with subclinical hypothyroidism-an ancillary study within two randomized placebo controlled trials

BACKGROUND

loss of skeletal muscle function, strength and mass is common in older adults, with important socioeconomic impacts. Subclinical hypothyroidism is common with increasing age and has been associated with reduced muscle strength. Yet, no randomized placebo-controlled trial (RCT) has investigated whether treatment of subclinical hypothyroidism affects muscle function and mass.

METHODS

this is an ancillary study within two RCTs conducted among adults aged ≥65 years with persistent subclinical hypothyroidism (thyrotropin (TSH) 4.60-19.99 mIU/l, normal free thyroxine). Participants received daily levothyroxine with TSH-guided dose adjustment or placebo and mock titration. Primary outcome was gait speed at final visit (median 18 months). Secondary outcomes were handgrip strength at 1-year follow-up and yearly change in muscle mass.

RESULTS

we included 267 participants from Switzerland and the Netherlands. Mean age was 77.5 years (range 65.1-97.1), 129 (48.3%) were women, and their mean baseline TSH was 6.36 mIU/l (standard deviation [SD] 1.9). At final visit, mean TSH was 3.8 mIU/l (SD 2.3) in the levothyroxine group and 5.1 mIU/l (SD 1.8, P < 0.05) in the placebo group. Compared to placebo, participants in the levothyroxine group had similar gait speed at final visit (adjusted between-group mean difference [MD] 0.01 m/s, 95% confidence interval [CI] -0.06 to 0.09), similar handgrip strength at one year (MD -1.22 kg, 95% CI -2.60 to 0.15) and similar yearly change in muscle mass (MD -0.15 m2, 95% CI -0.49 to 0.18).

CONCLUSIONS

in this ancillary analysis of two RCTs, treatment of subclinical hypothyroidism did not affect muscle function, strength and mass in individuals 65 years and older.

Regulatory Mechanisms of Muscle Mass: The Critical Role of Resistance Training in Children and Adolescent

Muscle mass and strength are subjected to several regulations. We found endocrine signals such as growth hormone, insulin-like growth factor 1, testosterone, thyroid hormones, and glucocorticoids among them. Neural inputs also influence muscle development, modulating mass and strength. Among the external stimuli that modulate these muscular features is physical training such as resistance and endurance training. Specifically, resistance training can mediate an increase in muscle mass by hypertrophy in adults, but the effects in children and adolescents are full of myths for most of the population. However, the evidence shows that the impact of resistance training on children and adolescents is clear and provides a wide range of benefits. However, qualified professionals must be available since exercise prescription and subsequent supervision must follow this population's abilities, needs, and interests.

Rhabdomyolysis Caused by Hypothyroidism: Research Progress

Rhabdomyolysis (RM) refers to the clinical syndrome caused by the release of intracellular substances into the extracellular fluid and blood circulation after rhabdomyocyte destruction due to various etiologies. In severe cases, RM can lead to life-threatening conditions such as acute kidney injury. Hypothyroidism is a rare cause of RM that can lead to missed diagnosis or misdiagnosis, and the condition worsens in the absence of timely and effective treatment. Herein, reported cases of RM caused by hypothyroidism are summarized, and clinical diagnosis and treatment recommendations are proposed to facilitate early identification and treatment of the disease.

Hashimoto Encephalopathy—Still More Questions than Answers

The normal function of the nervous system is conditioned by the undisturbed function of the thyroid gland and its hormones. Comprehensive clinical manifestations, including neurological disorders in Hashimoto’s thyroiditis, have long been understood and, in recent years, attention has been paid to neurological symptoms in euthyroid patients. Hashimoto encephalopathy is a controversial and poorly understood disease entity and the pathogenesis of the condition remains unclear. We still derive our understanding of this condition from case reports, but on the basis of these, a clear clinical picture of this entity can be proposed. Based on a review of the recent literature, the authors present the current view on the subject, discuss controversies and questions that still remain unanswered, as well as ongoing research in this area and the results of our own work in patients with Hashimoto’s thyroiditis.

Acute arthritis revealing Hashimoto's thyroiditis

Rheumatic manifestations can reveal hypothyroidism, such as arthritis and nonspecific musculoskeletal symptoms. We report herein the case of an acute polyarthritis revealing Hashimoto's thyroiditis (HT). Hormone replacement therapy leads to the resolution of arthritis related to HT, suggesting the role of thyroid hormone in the pathogenesis of arthritis.

Patient Factors Impacting Baseline Motor Evoked Potentials (MEPs) in Patients Undergoing Cervical Spine Surgery for Myelopathy or Radiculopathy

STUDY DESIGN

Retrospective review of 2532 adults who underwent elective surgery for cervical radiculopathy or myelopathy with intraoperative neuromonitoring (IONM) with motor evoked potentials (MEPs) between 2017 and 2019.

OBJECTIVE

Evaluate attainability of monitorable MEPs across demographic, health history, and patient-reported outcomes measure (PROM) factors.

SUMMARY OF BACKGROUND DATA

When baseline IONM responses cannot be obtained, the value of IONM on mitigating the risk of postoperative deficits is marginalized and a clinical decision to proceed must be made based, in part, on the differential diagnosis of the unmonitorable MEPs. Despite known associations with baseline MEPs and anesthetic regimen or preoperative motor strength, little is known regarding associations with other patient factors.

METHODS

Demographics, health history, and PROM data were collected preoperatively. MEP baseline responses were reported as monitorable or unmonitorable at incision. Multivariable logistic regression estimated the odds of having at least one unmonitorable MEP from demographic and health history factors.

RESULTS

Age [odds ratio (OR)=1.031, P <0.001], sex (male OR=1.572, P =0.007), a primary diagnosis of myelopathy (OR=1.493, P =0.021), peripheral vascular disease (OR=2.830, P =0.009), type II diabetes (OR=1.658, P =0.005), and hypertension (OR=1.406, P =0.040) were each associated with increased odds of unmonitorable MEPs from one or more muscles; a history of thyroid disorder was inversely related (OR=0.583, P =0.027). P atients with unmonitorable MEPs reported less neck-associated disability and pain ( P <0.036), but worse SF-12 physical health and lower extremity (LE) and upper extremity function ( P <0.016). Compared with radiculopathy, unmonitorable MEPs in myelopathy patients more often involved LE muscles. Cord function was monitorable in 99.1% of myelopathic patients with no reported LE dysfunction and no history of hypertension or diabetes.

CONCLUSION

Myelopathy, hypertension, peripheral vascular disease, diabetes, and/or symptomatic LE dysfunction increased the odds of having unmonitorable baseline MEPs. Unmonitorable baseline MEPs was uncommon in patients without significant LE weakness, even in the presence of myelopathy.

Is it really myositis? Mimics and pitfalls

Idiopathic inflammatory myopathies are a heterogeneous set of systemic inflammatory disorders primarily affecting muscle. Signs and symptoms vary greatly between and within subtypes, requiring supportive laboratory and pathologic evidence to confirm the diagnosis. Several studies are typical assessments for patients with suspected inflammatory myopathy, including muscle enzymes, autoimmune markers, imaging, and muscle biopsy. Misdiagnoses of myositis are not only related to the overlap of clinical phenotype with non-inflammatory myopathies, but also due to the limitations of diagnostic tests employed. Since many of the investigative tests are non-specific, they share features with other disorders, including muscular dystrophies, endocrine, toxic, and metabolic myopathies, and other neuromuscular or rheumatologic conditions. Recognizing the limitations of tests and understanding the shared features between inflammatory and non-inflammatory myopathies can help prevent misdiagnosing myositis with one of its several mimics.

Vitamin B12 (Cobalamin) Deficiency in Overt and Subclinical Primary Hypothyroidism

Background:

B12 (cobalamin) deficiency has been reported in hypothyroid patients with variable prevalence rates thus routine screening of hypothyroid patients was recommended by some and discouraged by others. We aimed to assess the prevalence of B12 deficiency among hypothyroid patients and to evaluate for pernicious anemia and celiac disease as etiologies.

Methods:

A total 133 patients were included. Thyroid hormones and thyroid peroxidase (TPO) autoantibodies were measured. Serum B12 was measured and if deficient, intrinsic factor antibodies (IFAB) and tissue transglutaminase (tTG) antibodies were evaluated.

Results:

Our study included 45 patients with overt hypothyroidism (OH), 48 patients with subclinical hypothyroidism (SCH), and 40 patients as controls. Mean age was 34.3 years and 82% were females. TPO antibodies were positive in 73.5% of OH and 51.1% of SCH patients. B12 deficiency was detected in 33.3%, 47.9%, and 37.5% of OH, SCH, and controls, respectively with no significant difference (P = .334). Borderline-to-low B12 level was more prevalent in the OH and the SCH groups compared to controls (68.9%, 85.4%, and 57.5%, respectively; P = .014). Among B12-deficient hypothyroid patients, 7.5% had positive IFAB and 13.3% had positive tTG antibodies. We did not find a significant association of TPO positivity and B12 deficiency (OR, 0.69; 95% CI 0.3-1.57; P = .147).

Conclusion:

We did not find a higher prevalence of B12 deficiency among hypothyroid patients nor an association with TPO positivity. Borderline B12 levels were more prevalent among hypothyroid patients.

Sympathetic skin responses and electromyographic reaction times in chronic autoimmune thyroiditis: An overlooked electrodiagnostic study

Objectives

This study aims to evaluate peripheral nerve functions, sympathetic skin responses (SSRs), and electromyographic (EMG) reaction times in hypothyroid patients and to compare them to healthy individuals.

Patients and methods

Between January 2007 and September 2007, a total of 54 patients with Hashimoto’s thyroiditis including 35 euthyroid (3 males, 32 females; mean age: 45.2±10.2 years; range, 35 to 60 years) and 19 with subclinical hypothyroidism (2 males, 17 females; mean age: 43.2±12.6 years; range, 40 to 65 years) were included in the study. The control group consisted of 35 healthy individuals (5 males, 30 females; mean age: 39.1±9.3 years; range, 29 to 52 years). Nerve conduction studies (NCSs), SSRs of the hand and foot obtained by stimulation of the contralateral median nerve, and EMG reaction times of the extensor indicis proprius muscle were performed in all subjects.

Results

There was no significant difference in peripheral NCSs and SSRs between patients and the control group. However, reaction times were longer in the AIT patients compared to the healthy individuals suggesting alterations in cognitive function related to the primary disease process in AIT.

Conclusion

Electrodiagnosis of autonomic nervous system involvement and cognitive impairment can be challenging in AIT. However, EMG reaction times and SSRs are practical and useful tools that are often overlooked. On the other hand, SSRs may be combined with more quantitative tests, such as sudomotor axon reflex testing, to allow us to better determine the extent of involvement of the autonomic nervous system in AIT.

Hypothyroidism is prevalent among adult women with chronic lower urinary tract symptoms

OBJECTIVE

To define the prevalence of hypothyroidism in women with chronic lower urinary tract symptoms (LUTS) and to compare the severity of each symptom between patients with hypothyroidism and controls.

SUBJECTS AND METHODS

In this prospective observational study, we screened all adult women who came to the urology clinic between March 2017 and September 2020, and enrolled patients with chronic LUTS in the study. We assessed thyroid function. We evaluated the severity of voiding and storage urinary symptoms by the International Prostate Symptom Score. We also assessed the severity of urge urinary incontinence (UUI) and stress urinary incontinence (SUI). For between-group analysis, we selected age-matched cases and controls and compared them regarding the distribution and severity of urinary symptoms.

RESULTS

Seven hundred and twenty-five women with a mean age of 51.7 ± 14.0 years were included in the final analysis. Two hundred fifty-eight patients (35.6%) had hypothyroidism. Age-matched case and control groups consisting of 210 patients each were selected. There was no significant difference in the severity and distribution of voiding LUTS and UUI between the study groups (P values >0.05). The severity of storage symptoms was lower in patients with hypothyroidism (P = 0.04). Sixty-seven patients with hypothyroidism (31.9%) had SUI, which was significantly higher than controls (23.3%) (P = 0.03).

CONCLUSION

More than one-third of women with chronic LUTS have hypothyroidism which is much more frequent than in the general population. We also suggest a possible relationship between hypothyroidism and the severity of SUI and an inverse relationship between hypothyroidism and storage symptoms.

Genetic factors contributing to late adverse musculoskeletal effects in childhood acute lymphoblastic leukemia survivors

BACKGROUND

A substantial number of survivors of childhood acute lymphoblastic leukemia (ALL) suffer from treatment-related late adverse effects. While multiple studies have identified the effects of chemotherapeutics and radiation therapy on musculoskeletal outcomes, few have investigated their associations with genetic factors.

METHODS

Here we analyzed musculoskeletal complications in relation to common and rare genetic variants derived through whole-exome sequencing of the PETALE cohort. Top-ranking associations were further assessed through stratified and multivariate analyses.

RESULTS

DUOX2 variant was associated with skeletal muscle function deficit, as defined by peak muscle power Z score ≤ -2 SD (P = 4.5 × 10^-5 for genotyping model). Upon risk stratification analysis, common variants in the APOL3, COL12A1, and LY75 genes were associated with Z score ≤ -2 SD at the cross-sectional area (CSA) at 4% radial length and lumbar bone mineral density (BMD) in high-risk patients (P ≤ 0.01). The modulation of the effect by risk group was driven by the interaction of the genotype with cumulative glucocorticoid dose. Identified variants remained significant throughout multivariate analyses incorporating non-genetic factors of the studied cohort.

CONCLUSION

This exploratory study identified novel genetic variants associated with long-term musculoskeletal impairments in childhood ALL survivors. Replication in an independent cohort is needed to confirm the association found in this study.

Multiple cranial nerve motor deficits, resembling polyneuritis cranialis, in a cat with hyperthyroidism

A 14 plus-year-old (exact age unknown) neutered female domestic shorthair cat presented with a 6-day history of rapidly evolving difficulty in eating, dropped jaw, protrusion of the tongue, sialosis, change in voice (meow softer and higher pitched) and mild variable pelvic limb weakness. Salient clinical features were a left thyroid nodule, 2/6 systolic cardiac murmur, poor body condition, hypertension, bilateral retinal haemorrhages and an increased total thyroid hormone level consistent with a diagnosis of hyperthyroidism (HT). Neurological examination disclosed mild generalised weakness, bilateral visual deficits attributable to a hypertensive retinopathy and multiple cranial nerve (CN) motor deficits that included; mandibular paresis (CN V), bilateral external ophthalmoparesis (CNs III, IV, VI), bilateral facial paresis (CN VII), dysphagia (CNs IX, X), dysphonia (CN XI) and symmetrical paresis of the tongue (CN XII). Treatment with carbimazole, and subsequently, a modified extracapsular bilateral thyroidectomy resulted in a rapid improvement in neurological signs over 13 days and complete resolution by 100 days post thyroidectomy. To the best of the authors' knowledge, this is the first description of multiple CN motor deficits in a cat with HT and resembles polyneuritis crainialis that has recently been described in human patients with this disorder. It is suggested the underlying pathogenesis is a thyrotoxic polyneuropathy selectively affecting CN motor function, that HT needs to be considered in cats that might present with such signs and that resolution can occur with successful treatment of the HT.

Adult-onset hypothyroidism causes mechanical hypersensitivity due to peripheral nerve hyperexcitability based on voltage-gated potassium channel downregulation in male mice

Thyroid hormones play an important role in the central and peripheral nervous system functions. Approximately 50% of adult-onset hypothyroid patients have sensory symptoms including pain, possibly caused by peripheral neuropathy. However, the mechanism causing the pain has not been clarified. We generated an adult-onset hypothyroid model animal by administering 50 ppm propylthiouracil (PTU) for 5 weeks to male mice. Female mice were not tested in this study. Mechanical hypersensitivity, determined by the von Frey hair test, was observed during the PTU exposure and recovered after the exposure termination. The sciatic nerve compound action potential was also analyzed. Under single-pulse stimulation, no significant change in the threshold and conduction velocity was observed in the PTU-administered group. On the other hand, under train-pulse stimulation, the latency delay in the Aδ-fiber component was less in the PTU-administered group in Week 4 of PTU exposure, indicating relative hyperexcitability. Fluticasone, which is the anti-inflammatory agent with an ability to activate the voltage-gated potassium channel subfamily A (Kv1), restored the decrease in the latency change ratio by PTU exposure under the train-pulse stimulation supporting our hypothesis that Kv1 may be involved in the conductivity change. Kv1.1 protein level decreased significantly in the sciatic nerve of the PTU-administered group. These results indicate that adult-onset hypothyroidism causes mechanical hypersensitivity owing to hyperexcitability of the peripheral nerve and that reduction of Kv1.1 level may be involved in such alteration.

Persisting neuroendocrine abnormalities and their association with physical impairment 5 years after critical illness

Background

Critical illness is hallmarked by neuroendocrine alterations throughout ICU stay. We investigated whether the neuroendocrine axes recover after ICU discharge and whether any residual abnormalities associate with physical functional impairments assessed 5 years after critical illness.

Methods

In this preplanned secondary analysis of the EPaNIC randomized controlled trial, we compared serum concentrations of hormones and binding proteins of the thyroid axis, the somatotropic axis and the adrenal axis in 436 adult patients who participated in the prospective 5-year clinical follow-up and who provided a blood sample with those in 50 demographically matched controls. We investigated independent associations between any long-term hormonal abnormalities and physical functional impairments (handgrip strength, 6-min walk distance, and physical health-related quality-of-life) with use of multivariable linear regression analyses.

Results

At 5-year follow-up, patients and controls had comparable serum concentrations of thyroid-stimulating hormone, thyroxine (T₄), triiodothyronine (T₃) and thyroxine-binding globulin, whereas patients had higher reverse T₃ (rT₃, p = 0.0002) and lower T₃/rT₃ (p = 0.0012) than controls. Patients had comparable concentrations of growth hormone, insulin-like growth factor-I (IGF-I) and IGF-binding protein 1 (IGFBP1), but higher IGFBP3 (p = 0.030) than controls. Total and free cortisol, cortisol-binding globulin and albumin concentrations were comparable for patients and controls. A lower T₃/rT₃ was independently associated with lower handgrip strength and shorter 6-min walk distance (p ≤ 0.036), and a higher IGFBP3 was independently associated with higher handgrip strength (p = 0.031).

Conclusions

Five years after ICU admission, most hormones and binding proteins of the thyroid, somatotropic and adrenal axes had recovered. The residual long-term abnormality within the thyroid axis was identified as risk factor for long-term physical impairment, whereas that within the somatotropic axis may be a compensatory protective response. Whether targeting of the residual abnormality in the thyroid axis may improve long-term physical outcome of the patients remains to be investigated.

Trial registration ClinicalTrials.gov: NCT00512122, registered on July 31, 2007 (https://www.clinicaltrials.gov/ct2/show/NCT00512122).

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03858-1.

Thyroid Hormone Action in Muscle Atrophy

Skeletal muscle atrophy is a condition associated with various physiological and pathophysiological conditions, such as denervation, cachexia, and fasting. It is characterized by an altered protein turnover in which the rate of protein degradation exceeds the rate of protein synthesis, leading to substantial muscle mass loss and weakness. Muscle protein breakdown reflects the activation of multiple proteolytic mechanisms, including lysosomal degradation, apoptosis, and ubiquitin-proteasome. Thyroid hormone (TH) plays a key role in these conditions. Indeed, skeletal muscle is among the principal TH target tissue, where TH regulates proliferation, metabolism, differentiation, homeostasis, and growth. In physiological conditions, TH stimulates both protein synthesis and degradation, and an alteration in TH levels is often responsible for a specific myopathy. Intracellular TH concentrations are modulated in skeletal muscle by a family of enzymes named deiodinases; in particular, in muscle, deiodinases type 2 (D2) and type 3 (D3) are both present. D2 activates the prohormone T4 into the active form triiodothyronine (T3), whereas D3 inactivates both T4 and T3 by the removal of an inner ring iodine. Here we will review the present knowledge of TH action in skeletal muscle atrophy, in particular, on the molecular mechanisms presiding over the control of intracellular T3 concentration in wasting muscle conditions. Finally, we will discuss the possibility of exploiting the modulation of deiodinases as a possible therapeutic approach to treat muscle atrophy.

Thyroid Hormone Plays an Important Role in Cardiac Function: From Bench to Bedside

Thyroid hormones (THs) are synthesized in the thyroid gland, and they circulate in the blood to regulate cells, tissues, and organs in the body. In particular, they exert several effects on the cardiovascular system. It is well known that THs raise the heart rate and cardiac contractility, improve the systolic and diastolic function of the heart, and decrease systemic vascular resistance. In the past 30 years, some researchers have studied the molecular pathways that mediate the role of TH in the cardiovascular system, to better understand its mechanisms of action. Two types of mechanisms, which are genomic and non-genomic pathways, underlie the effects of THs on cardiomyocytes. In this review, we summarize the current knowledge of the action of THs in the cardiac function, the clinical manifestation and parameters of their hemodynamics, and treatment principles for patients with hyperthyroid- or hypothyroid-associated heart disease. We also describe the cardiovascular drugs that induce thyroid dysfunction and explain the mechanism underlying the thyroid toxicity of amiodarone, which is considered the most effective antiarrhythmic agent. Finally, we discuss the recent reports on the involvement of thyroid hormones in the regulation of myocardial regeneration and metabolism in the adult heart.

Association between Thyroid Dysfunction and Intensive Care Unit-Acquired Weakness: A Case-Control Study

Background

Thyroid disorders may decrease the threshold for developing myopathy. Nonthyroidal illness syndrome (NTIS) is a common form of thyroid dysfunction in critically ill patients who are prone to the development of intensive care unit-acquired weakness (ICUAW). We therefore tested the hypothesis that patients with abnormalities in thyroid function are at a higher risk of developing ICUAW.

Methods

We assessed blood samples from patients admitted to the ICU for ≥7 days for thyroid functions. Patients were classified into 4 categories (euthyroid, hyperthyroid, hypothyroid, and NTIS). Patients were then evaluated daily for ICUAW development. Patients with ICUAW were considered as cases, whereas patients who did not develop ICUAW served as controls. We compared demographic and clinical variables, such as APACHE II score; length of ICU stay; free T3 (FT3), free T4, and thyroid-stimulating hormone levels; incidence of the four categories of thyroid function; and other risk factors for ICUAW. Logistic regression was used to determine independent risk factors for ICUAW.

Results

This case-control study included 114 patients: 57 cases (ICUAW) and 57 controls. FT3 levels were significantly lower in the cases (2.13 ± 0.96 mU/L) than in controls (2.69 ± 1.07 mU/L; P=0.004). There were no significant differences between cases and controls regarding the incidence of all categories of thyroid function. In univariate analysis, five independent variables had P < 0.25 (sepsis, vasopressors, mechanical ventilation duration, NTIS, and FT3 levels). Among these variables, multiple regression showed that only FT3 level (CI = 0.157-0.82, P=0.015) was an independent risk factor.

Conclusion

The study revealed an inverse association between ICUAW incidence and FT3 levels.

Disgusting odours affect the characteristics of the Adaptive Force in contrast to neutral and pleasant odours

The olfactomotor system is especially investigated by examining the sniffing in reaction to olfactory stimuli. The motor output of respiratory-independent muscles was seldomly considered regarding possible influences of smells. The Adaptive Force (AF) characterizes the capability of the neuromuscular system to adapt to external forces in a holding manner and was suggested to be more vulnerable to possible interfering stimuli due to the underlying complex control processes. The aim of this pilot study was to measure the effects of olfactory inputs on the AF of the hip and elbow flexors, respectively. The AF of 10 subjects was examined manually by experienced testers while smelling at sniffing sticks with neutral, pleasant or disgusting odours. The reaction force and the limb position were recorded by a handheld device. The results show, inter alia, a significantly lower maximal isometric AF and a significantly higher AF at the onset of oscillations by perceiving disgusting odours compared to pleasant or neutral odours (p < 0.001). The adaptive holding capacity seems to reflect the functionality of the neuromuscular control, which can be impaired by disgusting olfactory inputs. An undisturbed functioning neuromuscular system appears to be characterized by a proper length tension control and by an earlier onset of mutual oscillations during an external force increase. This highlights the strong connection of olfaction and motor control also regarding respiratory-independent muscles.

Adaptive Force and emotionally related imaginations - preliminary results suggest a reduction of the maximal holding capacity as reaction to disgusting food imagination

The link between emotions and motor control has been discussed for years. The measurement of the Adaptive Force (AF) provides the possibility to get insights into the adaptive control of the neuromuscular system in reaction to external forces. It was hypothesized that the holding isometric AF is especially vulnerable to disturbing inputs. Here, the behavior of the AF under the influence of positive (tasty) vs. negative (disgusting) food imaginations was investigated. The AF was examined in n = 12 cases using an objectified manual muscle test of the hip flexors, elbow flexors or pectoralis major muscle, performed by one of two experienced testers while the participants imagined their most tasty or most disgusting food. The reaction force and the limb position were measured by a handheld device. While the slope of force rises and the maximal AF did not differ significantly between tasty and disgusting imaginations (p > 0.05), the maximal isometric AF was significantly lower and the AF at the onset of oscillations was significantly higher under disgusting vs. tasty imaginations (both p = 0.001). A proper length tension control of muscles seems to be a crucial functional parameter of the neuromuscular system which can be impaired instantaneously by emotionally related negative imaginations. This might be a potential approach to evaluate somatic reactions to emotions.

Assessment of the Adaptive Force of Elbow Extensors in Healthy Subjects Quantified by a Novel Pneumatically Driven Measurement System with Considerations of Its Quality Criteria

Adaptive Force (AF) reflects the capability of the neuromuscular system to adapt adequately to external forces with the intention of maintaining a position or motion. One specific approach to assessing AF is to measure force and limb position during a pneumatically applied increasing external force. Through this method, the highest (AF_max), the maximal isometric (AFiso_max) and the maximal eccentric Adaptive Force (AFecc_max) can be determined. The main question of the study was whether the AFiso_max is a specific and independent parameter of muscle function compared to other maximal forces. In 13 healthy subjects (9 male and 4 female), the maximal voluntary isometric contraction (pre- and post-MVIC), the three AF parameters and the MVIC with a prior concentric contraction (MVICpri-con) of the elbow extensors were measured 4 times on two days. Arithmetic mean (M) and maximal (Max) torques of all force types were analyzed. Regarding the reliability of the AF parameters between days, the mean changes were 0.31–1.98 Nm (0.61%–5.47%, p = 0.175–0.552), the standard errors of measurements (SEM) were 1.29–5.68 Nm (2.53%–15.70%) and the ICCs(3,1) = 0.896–0.996. M and Max of AFiso_max, AF_max and pre-MVIC correlated highly (r = 0.85–0.98). The M and Max of AFiso_max were significantly lower (6.12–14.93 Nm; p ≤ 0.001–0.009) and more variable between trials (coefficient of variation (CVs) ≥ 21.95%) compared to those of pre-MVIC and AF_max (CVs ≤ 5.4%). The results suggest the novel measuring procedure is suitable to reliably quantify the AF, whereby the presented measurement errors should be taken into consideration. The AFiso_max seems to reflect its own strength capacity and should be detected separately. It is suggested its normalization to the MVIC or AF_max could serve as an indicator of a neuromuscular function.

Severe Hypothyroidism Complicated by Myopathy and Neuropathy with Atypical Demyelinating Features

Autoimmune hypothyroidism may result in a wide range of neuromuscular disorders. The frequently observed neurological manifestations of acquired hypothyroidism include mild to moderate myopathy and sensorimotor neuropathy, which usually resolve by clinical and electrophysiological criteria, in adults treated with thyroid hormone replacement. We report a case of a 30-year-old male with severe hypothyroidism secondary to chronic autoimmune thyroiditis who presented with a 2-year history of progressive fatigue, upper and lower limb weakness, myalgia, and intermittent paraesthesia. His neurological exam demonstrated proximal and distal muscle weakness, lower limb areflexia, and relatively intact sensory modalities. The patient's biochemistry revealed unusually and profoundly raised the thyroid stimulating hormone (TSH) level of 405.5 mIU/L (reference range (RR): 0.27–4.2 mIU/L) and creatine kinase (CK) level of 20,804 U/L (RR: 45–250 U/L), while his nerve conduction studies (NCS) demonstrated severe sensorimotor polyneuropathy with both axonal and demyelinating features. Thyroid hormone replacement therapy over the first 3 months resulted in biochemical normalization of his extremely deranged thyroid function tests (TFTs) and CK levels. At 12 months, despite maintaining euthyroidism and noticeable improvement in strength, his nerve conduction studies (NCS) demonstrated the continued absence of distal motor and sensory responses in his lower limbs with only partial improvement in sensory amplitudes and conduction velocities in his upper limbs. This report highlights the potential for severe neuromuscular consequences from advanced and chronic autoimmune hypothyroidism. The patient's myopathy has resolved over a period of three months with prompt normalization of CK levels. Concerningly, the patient achieved significant but incomplete recovery from his mixed axonal and demyelinating neuropathy with residual mild distal weakness and areflexia in his lower limbs and persistent motor and sensory impairments on his NCS. The severity and incomplete resolution of our patient's neurological manifestations emphasize the importance of early diagnosis and the need for prompt therapeutic intervention for hypothyroidism.

Coeliac disease is a risk factor for the development of seronegative arthritis in patients with autoimmune thyroid disease

OBJECTIVE

Hashimoto's thyroiditis is known to cluster with other systemic autoimmune disorders. Rheumatic manifestations, such as a seronegative non-erosive polyarthritis have been described. The aim of this study was to evaluate the characteristics and the prevalence of rheumatic features in thyroiditis patients, and to ascertain whether the association with systemic autoimmune disorders improved the arthritis manifestations.

METHODS

In total, 180 thyroiditis patients were enrolled. Major clinical and demographic characteristics have been recorded. Patients underwent a rheumatological clinical assessment and extra-articular manifestations allowing for a differential diagnosis with systemic autoimmune diseases and spondyloarthropathy. Presence of systemic autoimmune diseases was recorded.

RESULTS

A total of 8.33% of thyroiditis patients shown a peripheral inflammatory arthritis (P = 0.002). Female gender (P = 0.042) and thyroid peroxidase (TPOAbs) positivity (P = 0.001) were more frequent. In total, 37 patients had systemic autoimmune diseases (P = 0.0003). A significant high prevalence of coeliac disease and Addison disease was found (P = 0.034 and P = 0.049, respectively). In patients with coeliac disease, the articular manifestations were more frequent (21.21%) (P = 0.001) and the risk to develop joint involvement was 2.96.

CONCLUSION

Although we found an articular involvement in about one-third of thyroiditis patients, the prevalence of inflammatory arthropathy was only 8.33%. The prevalence of other coexisting autoimmune disorders was 34.26% with a significant prevalence of coeliac disease (7.41%). Thyroiditis patients with coeliac disease have an articular involvement more frequently than those without. In these patients, we have found a high risk of developing arthritis than patients with only thyroiditis, suggesting cumulative autoimmune effects in the developing articular involvement.

Underlying diseases in sporadic presentation of high creatine kinase levels in girls

BACKGROUND

Persistent creatine kinase (CK) elevation can occur due to various conditions. Identifying the causes of hyperCKemia is crucial for enabling appropriate follow-up and care. Girls with elevated CK levels may be carriers of Duchenne/Becker muscular dystrophy (DMD/BMD), making diagnosis more difficult than that in boys. This study aimed to elucidate the underlying causes of high CK levels in girls.

METHODS

Fourteen girls (seven symptomatic, seven asymptomatic) with persistently elevated CK levels but without a family history of muscle diseases were referred to our hospital between April 2014 and August 2018. Muscle biopsy and/or genetic analysis were conducted for diagnoses.

RESULTS

Among the symptomatic girls, six (85.7%) had muscular dystrophy (five DMD/BMD carriers, and one sarcoglycanopathy [limb-girdle muscular dystrophy: LGMDR4]), and one had dermatomyositis. Among the asymptomatic girls, four (57.1%) had muscular dystrophy (three DMD/BMD carriers, and one calpainopathy [LGMDR1]), and three were undiagnosed.

CONCLUSION

Our results indicate that muscular dystrophy, including DMD/BMD carriers, must be considered in girls with highperCKemia regardless of symptoms presentation, and in symptomatic girls with dermatomyositis. Investigations in girls with hyperCKemia should be performed under proper ethical considerations. Further research is necessary to develop a diagnostic strategy for girls with hyperCKemia.

Growth hormone replacement may influence the biological action of thyroid hormone on liver and bone tissue

OBJECTIVE

Growth hormone (GH) replacement alters the peripheral interconversion of thyroxine (T4) and triiodothyronine (T3). However, little is known about the clinical impact of these alterations. We aimed to compare changes observed in the serum T3:T4 ratio with known biological markers of thyroid hormone action derived from different peripheral tissues.

DESIGN

We prospectively studied twenty GH deficient men before and after GH replacement in a tertiary referral endocrine center. Serum biochemical measurements included insulin like growth factor-1 (IGF-1), thyroid hormones (free & total T3, free & total T4 and reverse T3) and TSH. Changes in thyroid hormone concentration were compared to alterations in hepatic and bone biomarkers of thyroid hormone action.

RESULTS

GH replacement provoked a decline in serum free T4 concentration (-1.09 ± 1.99 pmol/L; p = 0.02) and an increase in free T3 (+0.34 ± 0.15 pmol/L; p = 0.03); therefore, the free T3:free T4 ratio increased from 0.40 ± 0.02 to 0.47 ± 0.02 (p = 0.002). Sex hormone binding globulin (SHBG) level was unchanged. However, a decline in serum ferritin (-26.6 ± 8.5 ng/mL; p = 0.005) correlated with a fall in freeT4. Alterations in lipid profile, including a rise in large HDL sub-fractions and Lp (a) (+2.1 ± 21.1 nmol/L; p = 0.002) did not correlate with thyroid hormone levels. Significant increases were recorded in serum bone turnover markers - procollagen type 1 amino-terminal propeptide +57.4%; p = 0.0009, osteocalcin +48.6%; p = 0.0007; c-terminal telopeptides of type 1 collagen +73.7%; p = 0.002. Changes in bone formation markers occurred in parallel with fluctuations in thyroid hormone.

CONCLUSION

GH-induced alterations in the thyroid axis are associated with complex, tissue specific effects on thyroid hormone action. Modulation of bone turnover markers suggests that GH may improve the biological action of thyroid hormone on bone.

Levothyroxine Therapy in Elderly Patients With Hypothyroidism

Levothyroxine (L-T4) treatment of overt hypothyroidism can be more challenging in elderly compared to young patients. The elderly population is growing, and increasing incidence and prevalence of hypothyroidism with age are observed globally. Elderly people have more comorbidities compared to young patients, complicating correct diagnosis and management of hypothyroidism. Most importantly, cardiovascular complications compromise the usual start dosage and upward titration of L-T4 due to higher risk of decompensating cardiac ischemia and -function. It therefore takes more effort and care from the clinician, and the maintenance dose may have to be lower in order to avoid a cardiac incidence. On the other hand, L-T4 has a beneficial effect on cardiac function by increasing performance. The clinical challenge should not prevent treating with L-T4 should the patient develop e.g., cardiac ischemia. The endocrinologist is obliged to collaborate with the cardiologist on prophylactic cardiac measures by invasive cardiac surgery or medical therapy against cardiac ischemic angina. This usually allows subsequent successful treatment. Management of mild (subclinical) hypothyroidism is even more complex. Prevalent comorbidities in the elderly complicate correct diagnosis, since many concomitant morbidities can result in non-thyroidal illness, resembling mild hypothyroidism both clinically and biochemically. The diagnosis is further complicated as methods for measuring thyroid function (thyrotropin and thyroxine) vary immensely according to methodology and background population. It is thus imperative to ensure a correct diagnosis by etiology (e.g., autoimmunity) before deciding to treat. Even then, there is controversy regarding whether or not treatment of such mild forms of hypothyroidism in elderly will improve mortality, morbidity, and quality of life. This should be studied in large cohorts of patients in long-term placebo-controlled trials with clinically relevant outcomes. Other cases of hypothyroidism, e.g., medications, iodine overload or hypothalamus-pituitary-hypothyroidism, each pose specific challenges to management of hypothyroidism; these cases are also more frequent in the elderly. Finally, adherence to treatment is generally challenging. This is also the case in elderly patients, which may necessitate measuring thyroid hormones at individually tailored intervals, which is important to avoid over-treatment with increased risk of cardiac morbidity and mortality, osteoporosis, cognitive dysfunction, and muscle deficiency.

The prospective relationship between low muscle mass and thyroid hormones among 198 069 euthyroid men and women; comparing different definitions of low muscle mass

OBJECTIVE

The impact of thyroid hormones within normal range on muscle mass remains unknown. We examined the association between new onset of low muscle mass (LMM) and thyroid hormones among euthyroid men and women with three different definitions of LMM in prospective cohort study.

METHODS

We performed a cohort study of 198 069 Korean adults (mean age of 39.2 years), free of LMM at baseline, who participated in a repeated screening examination and were followed up annually or biennially for up to 6.3 years. Thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxin (FT4) levels were measured by an electrochemiluminescent immunoassay. Muscle mass was assessed using a bioelectrical impedance analyser. LMM was defined as the appendicular skeletal muscle mass (ASM) by body weight (ASM/weight, LMM-W), height squared (ASM/height² , LMM-H) and BMI (ASM/BMI, LMM-B) of one standard deviation below the sex-specific mean for young reference group.

RESULTS

During a median follow-up of 3.1 years (interquartile range, 2.0-4.1 years), new-onset LMM-W, LMM-H and LMM-B occurred in 17 856 (incident rate, 27.8 per 1000 person-years), 8307 (incident rate, 13.4 per 1000 person-years) and 13 990 participants (incident rate, 24.5 per 1000 person-years) in each. In euthyroid men, FT4 was inversely and FT3 positively associated with incident LMM-W in a dose-response manner. TSH and FT4 had inverse dose-response relationship with incident LMM-B. Incident LMM-H of euthyroid men has no apparent associations with any thyroid hormones. Euthyroid women had no dose-response relationship between thyroid hormones and any definition of LMM.

CONCLUSIONS

Among euthyroid men, FT4 had inverse dose-response association with new onset of LMM defined with weight (LMM-W) and BMI (LMM-B). Height squared LMM (LMM-H) had no apparent relationship with any thyroid hormones. Euthyroid women had no dose-responsive association between thyroid hormones and incident LMM.