From the Guidelines
The workup for polymyalgia rheumatica (PMR) should include a comprehensive clinical evaluation, laboratory tests, and sometimes imaging studies, as recommended by the 2015 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) collaborative initiative 1. The initial step in the workup for PMR is a thorough history focusing on symptoms like bilateral shoulder and hip girdle pain and stiffness, particularly worse in the morning.
- Key points to consider in the history include:
- Duration and severity of symptoms
- Presence of morning stiffness
- History of giant cell arteritis (GCA) or other autoimmune disorders Physical examination should assess for limited range of motion, muscle tenderness, and signs of GCA.
- Essential laboratory tests include:
- Erythrocyte sedimentation rate (ESR)
- C-reactive protein (CRP)
- Complete blood count
- Comprehensive metabolic panel
- Thyroid function tests
- Rheumatoid factor
- Anti-CCP antibodies These tests help exclude other conditions that may present similarly, such as rheumatoid arthritis, polymyositis, or malignancy 1. If GCA is suspected, temporal artery biopsy should be considered. Imaging studies like ultrasound may show characteristic bursitis and tenosynovitis. Diagnostic criteria include age over 50, bilateral shoulder/hip pain, morning stiffness >45 minutes, elevated inflammatory markers, and rapid response to low-dose prednisone (12.5-25 mg daily) 1. This systematic approach helps confirm PMR diagnosis while excluding other conditions that may present similarly. It is also important to assess comorbidities, other relevant medications, and possible risk factors for steroid-related side effects and relapse/prolonged therapy, as recommended by the EULAR/ACR guidelines 1.
From the Research
Work-up for Polymyalgia Rheumatica (PMR)
The work-up for PMR involves a combination of clinical evaluation, laboratory tests, and imaging studies. The key features of PMR include:
- Bilateral shoulder or pelvic girdle pain and stiffness, worse in the mornings 2
- Low-grade fever, malaise, fatigue, low mood, poor appetite, and weight loss 2
- Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels, although a small proportion of patients may have normal inflammatory markers 2, 3, 4
Laboratory Tests
The laboratory tests used to evaluate PMR include:
- ESR: elevated in most patients, but can be normal in some cases 3, 4, 5, 6
- CRP: elevated in most patients, and can be used to monitor disease activity 5, 6
- Complete blood count (CBC): may show anemia, leukocytosis, or thrombocytosis 2
- Liver function tests: may show elevated liver enzymes 2
- Thyroid function tests: to rule out thyroid disease 2
Imaging Studies
Imaging studies may be used to evaluate the extent of inflammation and to rule out other conditions, such as:
- X-rays: to evaluate the shoulders, hips, and spine for signs of inflammation or degenerative changes 2
- Ultrasound: to evaluate the shoulders and hips for signs of inflammation or tendinitis 2
- Magnetic resonance imaging (MRI): to evaluate the shoulders, hips, and spine for signs of inflammation or degenerative changes 2
Differential Diagnosis
The differential diagnosis for PMR includes:
- Giant cell arteritis (GCA): a condition that can cause similar symptoms, and may be associated with PMR 2
- Rheumatoid arthritis: a condition that can cause similar symptoms, but typically involves smaller joints 2
- Inflammatory muscle diseases: conditions that can cause muscle weakness and inflammation 2
- Thyroid disease: conditions that can cause muscle weakness, fatigue, and weight loss 2
- Malignancy: conditions that can cause weight loss, fatigue, and muscle weakness 2
- Infection: conditions that can cause fever, fatigue, and muscle weakness 2
- Bilateral shoulder capsulitis: a condition that can cause shoulder pain and stiffness 2
- Osteoarthritis: a condition that can cause joint pain and stiffness 2
- Parkinsonism: a condition that can cause muscle stiffness and weakness 2
- Depressive illness: a condition that can cause fatigue, weight loss, and muscle weakness 2