Discussion
Our patient had Basedow’s disease and presented with the rare chief
complaint of myalgia. Musculoskeletal symptoms and signs are common in
patients with thyroid dysfunction, as the skeletal muscle is a major
target of thyroid hormones. 4 Although hypothyroidism
is a thyroid function abnormality associated with myalgia,
hyperthyroidism is mainly associated with myopathy, such as muscle
weakness and wasting. Symptoms of myopathy primarily involve the
proximal muscles and rarely the pectoralis major muscle.5 Hyperthyroid myopathy usually resolves after
recovery from hyperthyroidism. In
the present case, the findings were atypical because there was no muscle
weakness, no muscular symptoms, and myalgia was not localised to the
muscles. Since myalgia in cases such as the presented one is rare,
careful consideration of the complications of concomitant disease is
needed, followed by a detailed medical interview, review of the system,
and systemic physical examination.
In recent years, cases of myalgia and elevated creatine kinase levels
during the treatment of hyperthyroidism have been presented, and the
side effects of anti-thyroid drugs and relative hypothyroidism have been
proposed as explanations for these muscle symptoms. 5However, the presented case is not consistent with relative
hypothyroidism because myalgia was present before treatment. Because T4
abnormalities cause abnormal glycogen degradation, abnormal
mitochondrial oxidative metabolism, and abnormal triglyceride turnover,
which impair muscle function,6 it is usually seen in
hypothyroidism, but may be affected in hyperthyroidism as well. Muscle
symptoms caused by Basedow’s disease require attention as they could be
complications of other autoimmune diseases. Basedow’s disease is rarely
associated with other autoimmune diseases, especially polymyositis and
myasthenia gravis. 7, 8 Further, the absence of other
features of muscle fatigue and myasthenia gravis in the present case
ruled out other autoimmune diseases. Similarly, periodic limb paralysis
is a rare and life-threatening complication of Basedow’s disease.9 It is characterised by recurrent episodes of
transient, flaccid muscle paralysis and affects the proximal muscles
more severely than distal muscles. The clinical course of the presented
case and normal serum potassium levels were inconsistent with periodic
quadriplegia. Furthermore, vitamin D deficiency can be an aetiological
factor for non-specific musculoskeletal pain. 10However, this possibility was ruled out because there was no evidence of
vitamin D deficiency in the present case. As in previous reports,11 the improvement in myalgia as well as the
simultaneous recovery of hyperthyroidism strongly suggests that
hyperthyroidism was the cause of the myalgia. To the best of our
knowledge, this is a very rare symptom of Basedow’s disease and has only
been reported in two previous cases. 9
In conclusion, we report on a patient with Basedow’s disease who
presented with the chief complaint of myalgia, which is a rare symptom.
In patients with Basedow’s disease who complain of muscular symptoms, it
is important to consider the disease mechanism as well as the presence
of other concomitant diseases; thyrotoxicosis could be a differential
diagnosis in such patients who present with myalgia.
Informed consent: We obtained informed consent from the
patient for publication of this case report.
Data accessibility: The datasets used and/or analyzed
during the current study are available from the corresponding author on
reasonable request.
Acknowledgments: None. This study did not receive any
funding.
Funding: None. This study did not receive any funding.
An ethics statement: We have obtained informed consent
from the patient for publication of this case report.
Conflict of Interest : None. We had no Conflict of
Interest.