What are the diagnostic criteria and treatment options for polymyalgia rheumatica (PMR)?

Diagnosis of Polymyalgia Rheumatica

PMR diagnosis requires a combination of clinical presentation (bilateral shoulder/hip girdle pain with morning stiffness in patients >50 years), elevated inflammatory markers (ESR and/or CRP), exclusion of mimicking conditions through specific laboratory testing, and should not rely on steroid response as a defining diagnostic feature. 1, 2

Clinical Presentation Requirements

• Patients must be 50 years or older with bilateral shoulder pain or stiffness, often accompanied by hip girdle and neck involvement 3
• Morning stiffness exceeding 1 hour is a key diagnostic feature 3
• Onset is typically acute or develops over days to weeks, with onset less than 2 weeks being particularly suggestive 3
• Bilateral upper arm tenderness on examination supports the diagnosis 3
• Constitutional symptoms including depression, weight loss, fatigue, and fever may be present but are not required 4, 3

Essential Laboratory Workup

Core Laboratory Panel (Must Be Obtained Before Treatment)

• ESR and/or CRP - inflammatory markers are essential, though ESR is preferred for long-term monitoring as high ESR (>40 mm/1st hour) predicts higher relapse rates 2, 5
• Rheumatoid factor and/or anti-CCP antibodies - to exclude rheumatoid arthritis 1, 2
• Complete blood count - to assess for anemia and exclude other inflammatory conditions 2
• Glucose, creatinine, liver function tests - establish baseline before glucocorticoid therapy 1, 2
• Bone profile (calcium, alkaline phosphatase) - assess bone health before steroid initiation 1, 2
• Urinalysis - exclude other inflammatory or infectious conditions 1, 2

Additional Recommended Tests

• Protein electrophoresis - excludes paraproteinemia mimicking PMR 2
• TSH - rules out thyroid disorders with similar presentation 2
• Creatine kinase - excludes myopathies and myositis 2
• Vitamin D - establishes baseline before glucocorticoid therapy 2

Extended Testing Based on Clinical Suspicion

• ANA and ANCA - when other autoimmune conditions are suspected 1, 2
• Tuberculosis testing - necessary before immunosuppressive therapy or in high-risk patients 2
• Chest radiograph - to exclude malignancy when clinically indicated 1, 2

Diagnostic Algorithm

1. Initial screening: Age >50 years + bilateral shoulder/hip pain + morning stiffness >1 hour 2, 3
2. Laboratory confirmation: Obtain core laboratory panel with ESR/CRP elevation (typically ESR >40 mm/h) 2, 5
3. Exclusion of mimics: Use laboratory panel to rule out rheumatoid arthritis, inflammatory myositis, endocrine disorders, infections, and malignancies 1, 2
4. Probable PMR diagnosis: Three or more of the following criteria: bilateral shoulder pain/stiffness, onset <2 weeks, ESR >40 mm/h, morning stiffness >1 hour, age ≥65 years, depression/weight loss, bilateral upper arm tenderness 3

Critical Diagnostic Pitfalls

• Do not use steroid response as a diagnostic criterion - while most patients respond promptly to 15-25 mg prednisone daily, response should not define PMR diagnosis 6, 4
• PMR with normal inflammatory markers exists - approximately 20% of patients have ESR <40 mm/h, more common in men and younger patients, representing a milder syndrome that still warrants treatment 7
• Normal ESR/CRP is an atypical presentation requiring specialist referral 5
• Avoid missing giant cell arteritis - PMR is associated with GCA, which requires more aggressive treatment 4

Indications for Specialist Referral

• Atypical presentations including peripheral inflammatory arthritis 2
• Systemic symptoms disproportionate to typical PMR 2
• Age <60 years 2
• High risk of treatment-related side effects 2
• Normal inflammatory markers despite typical clinical presentation 5

Important Clinical Context

• No single pathognomonic test exists - diagnosis remains primarily clinical, supported by laboratory inflammation evidence and exclusion of other disorders 2
• Female patients have higher relapse rates and require more vigilant monitoring 8
• High baseline ESR (>40 mm/1st hour) may indicate need for higher initial glucocorticoid doses and predicts prolonged therapy requirements 8, 5