From the Guidelines
Polymyalgia rheumatica (PMR) is diagnosed through a combination of clinical presentation, laboratory findings, and exclusion of other conditions, with a high erythrocyte sedimentation rate (ESR) (>40 mm/1st hour) being a key indicator, as recommended by the 2015 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) collaborative initiative 1. The diagnosis should be suspected in patients over 50 years old presenting with bilateral shoulder and hip girdle pain and morning stiffness lasting more than 45 minutes.
- Laboratory tests should include ESR and C-reactive protein (CRP), which are typically elevated (ESR >40 mm/hr) 1.
- Complete blood count, comprehensive metabolic panel, rheumatoid factor, anti-CCP antibodies, and thyroid function tests should be ordered to exclude other conditions.
- Imaging is not routinely required but may include ultrasound of shoulders and hips to detect bursitis or synovitis. A diagnostic trial of low-dose prednisone (15-20 mg daily) can be helpful, as patients with PMR typically show dramatic improvement within 24-72 hours, as supported by a systematic literature review informing the 2015 EULAR/ACR recommendations 1. If symptoms don't improve with steroids, consider alternative diagnoses. Always assess for temporal artery tenderness and visual symptoms to rule out giant cell arteritis, which requires immediate treatment with higher steroid doses (40-60 mg prednisone daily) 1. The diagnosis of PMR remains clinical, as there is no definitive test, and requires careful consideration of the patient's age, symptom pattern, inflammatory markers, and response to treatment, with the 2015 EULAR/ACR recommendations providing a framework for management 1.
From the Research
Diagnostic Criteria for Polymyalgia Rheumatica
- The diagnosis of polymyalgia rheumatica is made primarily on clinical grounds, with no single diagnostic test available 2.
- Diagnostic or classification criteria have been suggested by several groups of investigators, based on the typical clinical presentation and laboratory evidence of acute-phase reaction 2.
- The typical symptoms include bilateral aching of the shoulder girdle, associated with morning stiffness, and the neck and hip girdle may also be involved 2.
Laboratory Tests for Diagnosis
- Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are laboratory findings used in diagnosis and follow-up 3, 4.
- However, some patients with polymyalgia rheumatica may have normal ESR and CRP values at diagnosis or during relapse/recurrence 3, 4.
- In such cases, other acute phase reactants like serum amyloid A (SAA) can be used to support the diagnosis 4.
Imaging Studies for Diagnosis
- Medical imaging can help confirm and clarify diagnosis, assess response to treatment, and evaluate for relapses 5.
- Ultrasonography can be used to demonstrate bursitis in patients with normal ESR and CRP values, supporting the diagnosis of polymyalgia rheumatica 4.
Differential Diagnosis
- Other conditions that may mimic polymyalgia rheumatica, such as elderly-onset rheumatoid arthritis, must be excluded by appropriate testing and close monitoring of the disease course 2.
- A comprehensive review of the patient's symptoms, laboratory results, and medical history is necessary to make an accurate diagnosis 6.