Myopathy in hyperthyroidism as a consequence of rapid reduction of thyroid hormone: A case report

Myopathy Associated with Treatment of Graves’ Disease

Here, we report a case of an increase in serum creatine kinase (CK) concentration in an 11-year-old girl being treated for Graves’ disease with antithyroid drugs (ATDs). The patient complained of myalgia two weeks after methimazole treatment. Triiodothyronine (T3) and free thyroxine (FT4) levels were normal, but the serum CK level was significantly elevated. After switching to propylthiouracil, the serum CK level decreased to normal, and the myalgia was resolved. The development of myopathy during the treatment of hyperthyroidism may be considered as an adverse reaction of MMI. In this report, we present a rare pediatric case, along with a discussion on the possible causes of myopathy that occurred during the treatment of Graves’ disease. A careful follow-up (serum CK levels and thyroid function) and treatment reassessment should always be considered after antithyroid treatment.

The endocrinology of sarcopenia and frailty

Sarcopenia describes low muscle mass and strength associated with ageing, whilst reduced physical performance indicates the severity of the condition. It can happen independently of other medical conditions and can be a key feature of the frailty phenotype. Frailty is a syndrome of increased vulnerability to incomplete resolution of homeostasis, following a stressor event. Researchers have described the implications of hypothalamic pituitary dysregulation in the pathogenesis of both entities. This review summarizes the recent evidence in this area as well as other endocrine factors such as insulin resistance and vitamin D status and outlines current research priorities. We conducted searches to PubMed and Embase databases for articles, reviews and studies reporting new data on the interaction between hormones of the endocrine system and frailty and/ or sarcopenia in the last 5 years. Interventional studies, cohort studies, case-control studies and animal studies were included. Clinical trials register was also searched to identify ongoing relevant studies. Studies have given us insights into the complex relationships between factors such as anabolic hormones, glucocorticoids and vitamin D on muscle strength and performance and their involvement in ageing phenotypes. However, robust randomized controlled trials are needed to consolidate existing evidence in humans and inform clinical practice. Current evidence supports hormone replacement in patients with confirmed deficiencies, to optimize health and prevent complications. Hormone replacement has limited use for age-related conditions. Current interest is focused on muscle/bone/fat interactions and health outcomes in "sarcopenic obesity." A life-course approach to improving 'health-span' is advocated. Lifestyle factors such as nutrition and physical activity have important interactions with body composition, physical function and metabolic outcomes. Large-scale clinical trials will determine the efficacy and long-term safety of hormone supplementation in the management of sarcopenia and frailty.

Cross-sectional investigation of serum creatine kinase concentration in Graves disease patients treated with oral antithyroid drugs

Elevated serum creatine kinase (CK) concentration was reported in some Graves disease patients during the treatment with oral antithyroid drugs (ATD). The pathogenesis of this abnormal biochemical value was considered to be related to the therapeutic drug. However, the relevant epidemiological investigation was absent.Overall, 416 patients with Graves disease treated with oral ATDs were recruited from December 2017 to October 2019. Clinical characteristics such as the patient's medical history and therapeutic regimen were collected. Serum CK concentration and thyroid function were measured. Statistical analysis was adopted to clarify the relationship between serum CK level and these clinical parameters.Elevation of serum CK concentration was emerged in 13.5% patients who were treated with oral ATDs. The proportion was significantly higher among men than among women (19.5% vs 10.8%). There was no correlation between increased serum CK concentration and age. More than 60% of serum CK elevations occurred within 6 months after taking oral ATDs. Free triiodothyronine and free thyroxine are negatively correlated with serum CK concentration. The correlation coefficients are respectively -0.222 (P < .05) and -0.234 (P < .05). There is positive correlation between thyroid stimulating hormone and serum CK concentration. The correlation coefficient is 0.405 (P < .05). There was no statistical correlation between drug dosage and increased serum CK level.Increased serum CK level is a common adverse reaction of oral ATDs. It generally develops early after starting treatment. The cause of this adverse reaction is not clear. It is speculated that elevation of serum CK level is related to the fluctuation of thyroid function.

Endocrine myopathies: clinical and histopathological features of the major forms

Endocrinopathies, such as thyroid and parathyroid diseases, disorders of the adrenal axis, and acromegaly are included among the many causes of myopathy. Muscle disturbances caused by endocrine disorders are mainly due to alterations in the protein and carbohydrate metabolisms. Either a deficiency or excess of hormones produced by the glands can cause muscle dysfunction that can be reversed by starting hormone replacement therapy or acting on hormone dysfunction. The diagnosis is usually easy if a muscle disorder occurs in an overt endocrinopathy; however, in few patients, myopathy could be the first manifestation of the underlying endocrinopathy. In this article we discuss pathophysiology, clinical features and management of muscle involvement related to the major endocrine diseases.

Cognitive Deficits in Myopathies

Myopathies represent a wide spectrum of heterogeneous diseases mainly characterized by the abnormal structure or functioning of skeletal muscle. The current paper provides a comprehensive overview of cognitive deficits observed in various myopathies by consulting the main libraries (Pubmed, Scopus and Google Scholar). This review focuses on the causal classification of myopathies and concomitant cognitive deficits. In most studies, cognitive deficits have been found after clinical observations while lesions were also present in brain imaging. Most studies refer to hereditary myopathies, mainly Duchenne muscular dystrophy (DMD), and myotonic dystrophies (MDs); therefore, most of the overview will focus on these subtypes of myopathies. Most recent bibliographical sources have been preferred.

Myopathy after rapid correction of hyperthyroidism: A case report and review of literature

RATIONALE

Myalgia and elevated creatine kinase (CK) have been reported during the treatment of hyperthyroid patients. The causes of these symptoms are usually considered to be treatments of antithyroid drugs (ATDs), thyroidectomy or radio-iodine (131-I). However, the underlying cause may be the rapid correction of thyrotoxicosis (or relative hypothyroidism), which was usually neglected in clinical practice.

PATIENT CONCERNS

This report describes a case of a 25-year-old female with typical symptoms and laboratory test results of Grave hyperthyroidism. The patient complained about fatigue and myalgia 7 weeks after receiving methimazole (MMI) treatment. Blood tests showed dramatically elevated serum CK level, although free triiodothyronine (FT3) and free thyroxine (FT4) level had returned to the normal reference range. MMI was; therefore, discontinued and the patient's muscular symptoms disappeared quickly with the normalization of CK level and the relapse of hyperthyroidism. Later she received 131-I treatment and suffered similar muscular symptoms when FT3 and FT4 decreased to the normal range. This time, her symptoms were quickly relieved by levothyroxine (L-T4) replacement treatment.

DIAGNOSES

Myopathy induced by rapid correction of hyperthyroidism (or relative hypothyroidism).

INTERVENTIONS

MMI was discontinued after the patient's first episode of muscular symptoms. And for her second episode of muscular injury after 131-I treatment, we initiated L-T4 supplementation.

OUTCOMES

For the 2 episodes of muscular injury after ATDs or 131-I treatment, both of the interventions mentioned above brought a rapid relief of symptoms accompanied with normalization of CK level and restoration of thyroid hormone level.

LESSONS

Myopathy can be caused by a rapid reduction of thyroid hormone during the treatment of hyperthyroidism. This relative hypothyroidism syndrome should be considered if patients make complaints about fatigue and myalgia, even when thyroid hormone level is within the normal range during the antithyroid treatments. Serum CK level and thyroid function should be closely monitored post antithyroid treatments. Reduction of ATD dosage or replacement of thyroid hormone is suggested to relieve muscular symptoms.

Severe proximal myopathy secondary to Hashimoto’s thyroiditis

Muscular symptoms in hypothyroidism are common, including myalgia, fatigue and cramps; however, a significantly raised creatine kinase and muscle weakness are rare. Differential diagnosis of patients presenting with muscle weakness and a raised creatine kinase is wide, and hypothyroidism is rarely considered. We report this case of a 30-year-old female presenting with proximal muscle weakness as her primary symptom, hypothyroid symptoms of 3-month duration and a significantly raised creatine kinase. After ruling out other causes of a raised creatine kinase, thyroxine replacement was commenced, which led to complete resolution of her proximal weakness, myalgia and normalisation of creatine kinase level. This case illustrates severe proximal myopathy can be secondary to hypothyroidism, symptoms can resolve with thyroxine replacement and emphasises the importance of measuring thyroid function in patients with proximal weakness/myalgia and a significantly raised creatine kinase.