What is the diagnostic approach for polymyalgia rheumatica in a patient over 50 presenting with bilateral shoulder and hip girdle pain, morning stiffness >30 minutes, elevated erythrocyte sedimentation rate (ESR) and C‑reactive protein (CRP), normal creatine kinase, and rapid improvement with low‑dose prednisone?

Diagnostic Approach for Polymyalgia Rheumatica

Diagnose polymyalgia rheumatica clinically based on age >50 years, bilateral shoulder and hip girdle pain with morning stiffness >45 minutes, elevated ESR/CRP, normal creatine kinase, and dramatic improvement within 2-4 weeks of low-dose prednisone (12.5-25 mg/day). 1

Essential Diagnostic Criteria

The diagnosis is primarily clinical and requires:

Core Clinical Features

• Age >50 years (mandatory criterion)
• Bilateral shoulder and/or pelvic girdle pain lasting >2 weeks
• Morning stiffness >45 minutes (often several hours)
• Elevated inflammatory markers: ESR >40 mm/hour or elevated CRP 1, 2
• Normal creatine kinase (distinguishes from myopathy) 3

Confirmatory Response to Treatment

Clinical improvement should be evident within 2 weeks, with near-complete response by 4 weeks of prednisone 12.5-25 mg/day 1. This rapid, dramatic response is virtually pathognomonic—lack of response within 2 weeks should prompt reconsideration of the diagnosis 1, 4.

Critical Exclusions Before Diagnosis

Mandatory Screening for Giant Cell Arteritis

All patients must be evaluated for giant cell arteritis symptoms, as 30% have concurrent GCA 3. Screen for:

• New headache, scalp tenderness
• Jaw claudication
• Visual symptoms (diplopia, vision loss)
• Temporal artery abnormalities on examination 5, 6

If GCA features present, temporal artery biopsy is indicated and initial prednisone dose should be 40-60 mg/day, not the lower PMR dose 2.

Differential Diagnoses to Exclude

Consider specialist referral for atypical presentations 1:

• Peripheral inflammatory arthritis → suggests rheumatoid arthritis or spondyloarthropathy
• Age <60 years → less typical for PMR
• Normal inflammatory markers → reconsider diagnosis
• Systemic symptoms (fever, weight loss) → consider malignancy, infection, vasculitis
• Failure to respond to prednisone → suggests alternative diagnosis 4

Baseline Documentation Required

Before initiating glucocorticoids, document 1:

• Complete history and physical examination focusing on shoulder/hip girdle pain distribution
• ESR and CRP
• Creatine kinase (must be normal)
• Complete blood count
• Liver and renal function
• Assessment of comorbidities (diabetes, osteoporosis, hypertension, glaucoma)
• Risk factors for glucocorticoid-related adverse events

Role of Imaging

Ultrasonography can support the diagnosis by demonstrating bilateral subdeltoid bursitis, subacromial-subdeltoid bursitis, or glenohumeral synovitis 6, 4, 7. However, imaging is not mandatory if clinical criteria are met.

Common Diagnostic Pitfalls

Avoid Overdiagnosis

Many conditions mimic PMR 4:

• Rheumatoid arthritis with late onset
• Spondyloarthropathy
• Rotator cuff disease or adhesive capsulitis
• Osteoarthritis
• Myopathy
• Malignancy
• Infection

Normal ESR Does Not Exclude PMR

A normal ESR occurs in some cases and does not exclude the diagnosis 2, though it should prompt careful consideration of alternatives. CRP may be elevated when ESR is normal.

Beware of Glucocorticoid Dependency

If patients require prednisone >30 mg/day for symptom control, strongly reconsider the diagnosis—this suggests an alternative condition 1.

Practical Diagnostic Algorithm

1. Patient >50 years with bilateral shoulder/hip pain and morning stiffness >45 minutes → Check ESR/CRP and creatine kinase
2. If ESR/CRP elevated and CK normal → Screen for GCA symptoms
3. If no GCA features → Start prednisone 12.5-25 mg/day (lower dose if comorbidities present) 1
4. Assess response at 2 weeks → Dramatic improvement confirms PMR diagnosis 1
5. If inadequate response → Increase to 25 mg/day or reconsider diagnosis 1
6. If still no response → Diagnosis is likely incorrect; pursue alternative diagnoses 4