musculoskeletal and connective tissue disorders
Polymyalgia Rheumatica
Diagnosis of Polymyalgia Rheumatica
Clinical findings Exclusion of other causes Polymyalgia rheumatica is suspected in older patients with typical symptoms, but other possible causes must be excluded. Tests include erythrocyte sedimentation rate (ESR), C-reactive protein, complete blood count, thyroid-stimulating hormone levels, and CK. In>80% of patients, ESR is markedly elevated, often>100 mm/hour, usually>50 mm/hour (Westergren method). C-reactive protein is also elevated. Electromyography, biopsy, and other tests (eg, rheumatoid factor), which are normal in polymyalgia rheumatica, are sometimes done to rule out other clinically suspected diagnoses. The following findings in polymyalgia rheumatica distinguish it from Rheumatoid Arthritis (RA) : In polymyalgia rheumatica, chronic small-joint synovitis, erosive or destructive lesions, rheumatoid nodules, and rheumatoid factor are absent in about 80% (although some joint swelling may be present) of patients. Differentiation from rheumatoid arthritis may be difficult in the remaining 20%. Autoimmune Myositis : In polymyalgia rheumatica, pain rather than weakness predominates; muscle enzyme levels and electromyography and muscle biopsy results are normal. Hypothyroidism : In polymyalgia rheumatica, thyroid function test results and muscle enzyme levels are normal. Multiple Myeloma : In polymyalgia rheumatica, monoclonal gammopathy is absent. Fibromyalgia : In polymyalgia rheumatica, symptoms are more localized, ESR is typically elevated, and pain is present with palpation and range of motion (active and passive) of the shoulders, even when the patient is distracted. 