In a patient over 50 years old with bilateral shoulder and pelvic girdle pain, morning stiffness lasting more than 30 minutes, and normal inflammatory markers (ESR and CRP), how should polymyalgia rheumatica be diagnosed and managed?

Polymyalgia Rheumatica with Normal Inflammatory Markers

PMR can and does occur with normal ESR and CRP in approximately 14-20% of cases, and these patients should still be treated with glucocorticoids (12.5-25 mg prednisone daily) if they meet clinical criteria, though specialist referral is strongly recommended for atypical presentations including low inflammatory markers. 1

Diagnostic Approach

Clinical Diagnosis Remains Primary

• PMR diagnosis is fundamentally clinical, not laboratory-based, requiring: age ≥50 years, bilateral shoulder and/or pelvic girdle pain, morning stiffness >30 minutes, and rapid response to low-dose glucocorticoids 1

• Normal inflammatory markers occur in 14-20% of confirmed PMR cases and represent a recognized atypical presentation 2, 3

Key Distinguishing Features of PMR with Normal Markers

Patients with PMR and ESR <40 mm/h demonstrate specific characteristics:

• Younger age at diagnosis (though still >50 years) 2, 3
• Male predominance (opposite of typical PMR) 2
• Longer symptom duration before diagnosis 3
• Lower frequency of constitutional symptoms (fever, weight loss) 2
• Absence of anemia 2
• Lower comorbidity burden 3

Alternative Inflammatory Markers

• Serum amyloid A (SAA) is elevated in all PMR patients with normal ESR/CRP and should be measured when clinical suspicion is high but standard markers are normal 3

• Ultrasound demonstrating bilateral subdeltoid bursitis provides objective evidence supporting PMR diagnosis when inflammatory markers are normal 4, 3

Mandatory Specialist Referral Criteria

The EULAR/ACR guidelines strongly recommend specialist referral for atypical presentations including 1:

• Low inflammatory markers
• Age <60 years
• Peripheral inflammatory arthritis
• Systemic symptoms
• Refractory disease or frequent relapses

This is critical: Normal inflammatory markers warrant rheumatology consultation to exclude mimicking conditions (elderly-onset rheumatoid arthritis, malignancy, infection, myopathy, vasculitis) 5, 4, 6

Management Strategy

Initial Glucocorticoid Therapy

Start prednisone 12.5-25 mg daily even with normal inflammatory markers if clinical criteria are met 1:

• Use lower end of range (12.5-15 mg) in patients with comorbidities (diabetes, osteoporosis, glaucoma) 1
• Never use >30 mg/day (strongly contraindicated) 1
• Avoid ≤7.5 mg/day as initial dose (conditionally discouraged) 1

Tapering Protocol

Taper to 10 mg/day within 4-8 weeks, then reduce by 1 mg every 4 weeks once remission achieved 1

Monitoring Considerations

Critical caveat: Relapses can occur despite normal ESR/CRP, particularly in patients initially presenting with normal markers 7

• Monitor clinical symptoms primarily, not just laboratory values 7, 8
• Follow-up every 4-8 weeks in first year, every 8-12 weeks in second year 1
• Document disease activity, glucocorticoid-related adverse events, and comorbidities at each visit 1

Glucocorticoid-Sparing Agents

Consider early methotrexate (7.5-10 mg/week) in patients with 1:

• High risk for prolonged therapy
• Significant comorbidities increasing glucocorticoid toxicity risk
• Relapsing disease

IL-6 receptor blockers (tocilizumab) should be considered for glucocorticoid-dependent or relapsing disease per updated 2024 guidelines 9

Response Assessment

Expect rapid clinical improvement within days to 1-2 weeks if diagnosis is correct 2, 5:

• Failure to respond suggests alternative diagnosis (giant cell arteritis, malignancy, infection) 4
• Screen for giant cell arteritis at every visit: headache, jaw claudication, visual symptoms 5, 10

Clinical Pitfalls

Do Not Dismiss PMR Based on Normal Markers Alone

The most important pitfall: Withholding treatment because ESR/CRP are normal in a patient with classic clinical features 2, 3

• This represents a more benign syndrome with less systemic inflammation but identical treatment response 2
• These patients benefit equally from glucocorticoid therapy 2

Recognize This is a Distinct Phenotype

PMR with normal inflammatory markers is clinically less severe but requires the same therapeutic approach 2:

• Less constitutional symptoms
• Preserved hemoglobin
• Similar relapse rates
• Identical treatment duration requirements

Monitor for Treatment Complications

28% develop hyperglycemia and 14% develop osteoporosis on glucocorticoid therapy 10:

• Implement bone protection (calcium, vitamin D, bisphosphonates if indicated)
• Monitor glucose, blood pressure, weight
• Consider individualized exercise program 1