A 45-year-old woman comes to the office due to progressive fatigue, myalgias, and muscle weakness in both lower extremities for the past month. She has slight difficulty getting up from a chair, and has weakness and cramping in the legs after walking a short distance. The patient's other medical problems include hypertension, which is treated with lisinopril. She does not use tobacco, alcohol, or illicit drugs. Blood pressure is 140/80 mm Hg, pulse is 64/min, and respirations are 14/min. Examination shows mildly decreased strength in the proximal muscles of the lower extremities with sluggish ankle jerks bilaterally. Laboratory tests show a normal erythrocyte sedimentation rate and an elevated serum creatine kinase level. Serum sodium, glucose, potassium, and creatinine are normal. Which of the following is the most appropriate next step in management of this patient?

Question

A 45-year-old woman comes to the office due to progressive fatigue, myalgias, and muscle weakness in both lower extremities for the past month.  She has slight difficulty getting up from a chair, and has weakness and cramping in the legs after walking a short distance.  The patient's other medical problems include hypertension, which is treated with lisinopril.  She does not use tobacco, alcohol, or illicit drugs.  Blood pressure is 140/80 mm Hg, pulse is 64/min, and respirations are 14/min.  Examination shows mildly decreased strength in the proximal muscles of the lower extremities with sluggish ankle jerks bilaterally.  Laboratory tests show a normal erythrocyte sedimentation rate and an elevated serum creatine kinase level.  Serum sodium, glucose, potassium, and creatinine are normal.  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

11ec25c8_d25b_2c51_bc81_6b17b1083677_MD0003_00 This patient has myalgias and proximal muscle weakness with an elevated serum creatine kinase (CK) level. In a relatively young, otherwise healthy woman with fatigue and delayed deep tendon reflexes, this presentation is most consistent with hypothyroid myopathy. Myopathy occurs in over one third of patients with hypothyroidism, and can range from an asymptomatic elevation in CK to myalgias, muscle hypertrophy, proximal myopathy, and rhabdomyolysis. Serum CK can be elevated for years before a patient develops clinical symptoms of hypothyroidism, and there is no clear correlation between the degree of CK elevation and severity of muscle disease. Inflammatory markers (eg, erythrocyte sedimentation rate, C-reactive protein) may be normal or mildly elevated. Initial testing should include TSH and free T4. If thyroid studies are normal, additional testing, including serologic markers (eg, antinuclear antibodies, anti-Jo-1 antibodies) and muscle biopsy, may be needed to rule out other causes of myositis (Choice A). (Choice B) Myopathy with elevated CK concentration usually is not a manifestation of lisinopril toxicity. The most common drugs associated with myopathy are corticosteroids, statins, and colchicine. (Choice C) Electromyogram in patients with hypothyroid myopathy can be normal or show nonspecific changes. It is more helpful in evaluating patients with polymyositis and can be considered if thyroid studies are normal. (Choice D) Polymyositis is characterized by symmetric proximal muscle weakness. Sedimentation rate and CK are elevated in approximately half of patients, and the diagnosis can be confirmed with muscle biopsy. However, myalgias are typically absent or mild and deep tendon reflexes are normal. Educational objective: Hypothyroid myopathy is characterized by myalgias, proximal muscle weakness, and an elevated serum creatine kinase level. Patients often have additional features of hypothyroidism (eg, fatigue, delayed reflexes). Initial diagnostic testing includes TSH and free T4 levels.

A 45-Year-Old Woman Comes to the Office Due to Progressive