From the Guidelines
Polymyalgia rheumatica (PMR) is diagnosed primarily through clinical evaluation, laboratory findings, and exclusion of other conditions, with a dramatic response to low-dose glucocorticoids being a key diagnostic feature. The diagnosis of PMR requires a combination of clinical criteria, including age over 50 years, bilateral shoulder and/or hip girdle pain and stiffness lasting at least 2 weeks, and elevated inflammatory markers (ESR typically >40 mm/hr and/or CRP >10 mg/L) 1. Morning stiffness lasting more than 45 minutes is characteristic, and physical examination may reveal limited range of motion in shoulders and hips due to pain rather than true weakness.
Key Diagnostic Criteria
- Age over 50 years
- Bilateral shoulder and/or hip girdle pain and stiffness lasting at least 2 weeks
- Elevated inflammatory markers (ESR typically >40 mm/hr and/or CRP >10 mg/L)
- Dramatic response to low-dose glucocorticoids
Laboratory tests should include complete blood count, comprehensive metabolic panel, ESR, CRP, rheumatoid factor, and anti-CCP antibodies to exclude other conditions 1. Imaging is not routinely required but may include ultrasound to detect subdeltoid bursitis or biceps tenosynovitis. A therapeutic trial of prednisone (12.5-25 mg daily) with significant improvement within 1-3 days strongly supports the diagnosis 1. It's essential to evaluate for giant cell arteritis, which coexists in about 15-30% of PMR patients, by checking for headache, jaw claudication, visual disturbances, and temporal artery tenderness 1.
Evaluation and Management
- Evaluate for giant cell arteritis
- Check for headache, jaw claudication, visual disturbances, and temporal artery tenderness
- Consider specialist referral for atypical presentation or high risk of therapy-related side effects
- Document a minimal clinical and laboratory dataset before prescribing therapy 1
No single test confirms PMR, making it a clinical diagnosis that requires careful consideration of symptoms, laboratory findings, and response to treatment 1.
From the Research
Diagnosis of Polymyalgia Rheumatica
The diagnosis of polymyalgia rheumatica (PMR) is typically based on clinical presentation and an increase in inflammatory markers 2, 3, 4. Some key points to consider in the diagnosis of PMR include:
- Clinical symptoms such as bilateral aching of the shoulder girdle, associated with morning stiffness, and involvement of the neck and hip girdle 3
- Laboratory evidence of acute-phase reaction, although a normal erythrocyte sedimentation rate (ESR) does not exclude the diagnosis 5, 6
- Imaging techniques, especially ultrasonography, can assist in the identification of PMR 2
- Exclusion of other conditions that may mimic PMR, such as elderly-onset rheumatoid arthritis, through appropriate testing and close monitoring of the disease course 3
Diagnostic Criteria
There are no pathognomonic findings that can confirm the diagnosis of PMR, but sets of 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 3. A proposed set of criteria can be applied in daily practice to patients with a clinical picture consistent with PMR but with a normal or slightly increased ESR 5.
Challenges in Diagnosis
The diagnosis of PMR can be challenging, especially in patients with a normal ESR, as the lack of characteristically abnormal laboratory findings may result in a delay in the proper diagnosis and management of this condition 6. Additionally, PMR symptoms can overlap with those of several other conditions, making diagnosis more difficult 4.
Role of ESR in Diagnosis
A normal ESR does not exclude the diagnosis of PMR, as a sizable proportion of patients with PMR have been reported to have a normal or slightly increased ESR at the time of diagnosis 5, 6. In fact, studies have shown that approximately 7-22% of patients with PMR have a normal ESR 5, 6.