Overview.
Hypothyroidism myopathy (HM) is a condition in which hypothyroidism (short for hypothyroidism) involves the muscles and causes muscle damage. Patients are characterized by hypothyroidism with proximal muscle weakness and elevated muscle enzyme profiles, which return to normal after receiving thyroxine therapy, which is rare clinically. Thyroid function tests are helpful in clarifying the diagnosis in patients with myopathic manifestations such as post-exercise muscle pain, myotonia, and myohypertrophy.
Etiology
Hypothyroid myopathy is caused by myogenic lesions, and it is now believed that the occurrence of this disease may be related to rhabdomyolysis.
Symptoms
The main manifestations are proximal muscle weakness, muscle pain on exercise, muscle tonus and muscle hypertrophy. Weakness, muscle tonus, and delayed tendon reflexes are the most common common symptoms of the disease. Generalized weakness, especially aggravated by activity, may be accompanied by chills and easy fatigue.
Examination
Laboratory tests show elevated muscle enzymes, decreased thyroid hormone levels, and elevated thyrotropin levels. Electromyography shows predominantly myogenic damage.
Diagnosis
The diagnosis is made on the basis of the history of hypothyroidism, clinical manifestations such as muscle weakness, muscle pain after exercise, and myotonia, supplemented by thyroid function tests and electromyography.
Differential diagnosis
This disease should be differentiated from polymyositis: hypothyroid myopathy and polymyositis have similar clinical manifestations in muscle, and the diagnostic criteria are similar: both have proximal muscle weakness and elevated muscle enzyme profiles, but polymyositis is an autoimmune disease, in addition to muscle weakness and elevated muscle enzymes, electromyography and muscle biopsy have specific changes, and autoantibodies can be detected in laboratory tests, and hormonal treatment is mostly effective. Most of them are effective and can be caused by malignant tumors, infections and other autoimmune diseases. Hypothyroid myopathy can involve not only proximal limb muscles, shoulder girdle muscles, pelvic girdle muscles, but also distal limb muscles; acute inflammation index, autoantibodies, muscle pathology results are different, thyroid function test can help to distinguish the two.
Treatment
Thyroid hormone replacement therapy is used.
Prognosis
The prognosis of this disease is good.