A 69-year-old man comes to the physician with bilateral shoulder and thigh pain for 2-3 months. The pain is associated with prolonged morning stiffness. He also complains of new-onset intermittent right-sided headaches and jaw pain. His only other medical problem is hypertension. The patient's medications include acetaminophen, lisinopril, and chlorthalidone. Examination shows no significant neck, shoulder, or thigh tenderness. He has normal passive range of motion at the shoulders but bilateral stiffness with active abduction. Joints show no obvious synovitis. Neurologic examination, including muscular strength, is normal. Which of the following is the most appropriate screening test for this patient?
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This patient with age >50 and subacute onset of diffuse muscle pain and stiffness has characteristic features of polymyalgia rheumatica (PMR). In PMR, the physical examination is frequently unremarkable, with little or no significant muscle or joint tenderness. Patients may have mild stiffness with active range of motion (ROM), but passive ROM is usually normal. Signs of inflammation in the joints are minimal to absent. This patient's headaches and jaw pain raise the possibility of associated giant cell arteritis (GCA), also known as temporal arteritis, which frequently accompanies PMR. Untreated GCA can lead to ischemic optic neuritis and vision loss and requires urgent evaluation.
The diagnoses of PMR and GCA are primarily clinical, but erythrocyte sedimentation rate (ESR) should be obtained for confirmation and is highly sensitive. In patients age >50 with a new, localized headache or tenderness of the temporal artery, ESR >50 mm/h is 91% specific for GCA. If GCA is suspected, patients should be considered for an expedited temporal artery biopsy and should receive high-dose glucocorticoids (eg, prednisone 40-60 mg or more daily) while the evaluation is in progress.
(Choices A and B) Aldolase and creatine kinase are markers of myocyte injury and are used to rule out myopathies such as polymyositis. Polymyositis may occasionally mimic PMR, but it is generally characterized by muscle weakness with little or no associated pain.
(Choice D) This patient has large muscle (shoulders and thighs) pain with subjective muscular stiffness, typical for PMR. By contrast, rheumatoid arthritis is characterized by pain and stiffness in the joints themselves, especially the small joints of the hands. Rheumatoid arthritis also usually has signs of synovitis at the time of presentation.
(Choice E) Although hypothyroid myopathy can present with generalized muscle pain, it typically has significant associated weakness. Hypothyroid myopathy usually develops in the context of florid hypothyroidism with fatigue, weight gain, and cold intolerance.
Educational objective:
Polymyalgia rheumatica (PMR) affects patients age >50 and is characterized by pain in the large muscles of the shoulders and pelvic girdle. Headache, jaw pain, visual loss, or temporal tenderness suggests the presence of giant cell arteritis, which often accompanies PMR. The diagnosis of PMR is primarily clinical, and erythrocyte sedimentation rate should be obtained for confirmation. Patients with possible giant cell arteritis should receive high-dose glucocorticoids and be considered for temporal artery biopsy.