How is polymyalgia rheumatica diagnosed in a patient over 50 (typically a woman in her 70s) presenting with sudden symmetric shoulder and hip girdle pain, morning stiffness lasting at least 30 minutes, elevated erythrocyte sedimentation rate and C‑reactive protein, and rapid improvement with low‑dose prednisone (10–20 mg daily)?

How to Diagnose Polymyalgia Rheumatica

Polymyalgia rheumatica is diagnosed clinically in patients over 50 years presenting with bilateral shoulder and/or hip girdle pain, morning stiffness exceeding 45 minutes, elevated inflammatory markers (ESR and/or CRP), and dramatic improvement within days to 2 weeks on low-dose prednisone (12.5–25 mg daily), after excluding mimicking conditions through targeted laboratory testing. 1, 2

Patient Age and Demographics

• Age ≥50 years is mandatory for diagnosis—PMR occurs almost exclusively in this population, with peak incidence around age 75. 1, 3, 4
• Patients under 60 years require immediate specialist rheumatology referral, as this represents an atypical presentation that raises concern for alternative diagnoses including malignancy, infection, or other inflammatory conditions. 1, 3
• Women are affected 2–3 times more frequently than men and face higher relapse rates and glucocorticoid-related complications. 1, 3

Core Clinical Features to Assess

• Bilateral shoulder pain and/or pelvic girdle aching lasting ≥2 weeks is the hallmark symptom. 1, 2
• Morning stiffness duration >45 minutes (often several hours) is a key discriminating feature. 1, 2
• Pain and limitation of active shoulder motion on examination (84% agreement among experts) and/or hip motion (76% agreement) should be documented. 2
• Assess for functional impairment—patients typically struggle with overhead activities, rising from chairs, or getting out of bed. 1
• Constitutional symptoms (fever, weight loss, fatigue) may be present but are not required. 5

Essential Laboratory Workup

Core Tests to Confirm Inflammation and Exclude Mimics

• ESR and/or CRP must be obtained—typically markedly elevated (ESR often >40 mm/1st hour), though 7–22% of genuine PMR cases have normal or minimally elevated ESR. 1, 5, 2
• When ESR is normal or borderline, CRP is often elevated and should always be checked. 1, 5
• Rheumatoid factor and/or anti-CCP antibodies exclude rheumatoid arthritis. 1, 6
• Complete blood count assesses for anemia of inflammation and excludes hematologic malignancy. 1
• Creatine kinase must be normal—elevation suggests inflammatory myositis rather than PMR. 7, 1

Baseline Tests Before Glucocorticoid Therapy

• Glucose, creatinine, liver function tests establish baseline organ function. 1, 6
• Bone profile (calcium, alkaline phosphatase) and vitamin D assess bone health before steroid exposure. 1
• Urinalysis excludes renal or infectious pathology. 1

Additional Tests Based on Clinical Context

• Protein electrophoresis excludes paraproteinemia mimicking PMR. 1
• TSH rules out thyroid disorders with similar presentations. 1
• ANA and ANCA when other autoimmune conditions or vasculitis are suspected. 1
• Tuberculosis testing before immunosuppressive therapy or in high-risk patients. 1
• Chest radiograph excludes malignancy or alternative thoracic diagnoses. 1

Diagnostic Therapeutic Trial

• Initiate prednisone 12.5–25 mg daily (individualize within this range based on risk factors). 1, 6, 2
• Patients with high ESR (>40 mm/hr), female sex, or peripheral arthritis may require doses toward the higher end (20–25 mg). 1
• Expect rapid, dramatic improvement within 1 week—typically >75% global symptom response within days to 2 weeks. 1, 2
• Lack of substantial response within 2 weeks should prompt dose escalation up to 25 mg/day or reconsideration of the diagnosis. 1

Critical Differential Diagnoses to Exclude

• Rheumatoid arthritis (check RF/anti-CCP, look for small joint synovitis). 1, 6, 4
• Giant cell arteritis (assess for headache, jaw claudication, visual symptoms, temporal artery tenderness). 7, 1
• Inflammatory myositis (check CK, assess for true weakness vs. pain-limited strength). 7, 1, 6
• Malignancy (especially in atypical presentations or older patients with weight loss). 1, 3, 8
• Infection (including endocarditis, osteomyelitis). 1, 3
• Endocrine disorders (hypothyroidism, hyperparathyroidism). 1, 4
• Crystal arthropathies and septic arthritis if joint involvement is present. 7
• RS3PE syndrome, spondyloarthropathy, SLE, vasculitis in atypical cases. 3

Indications for Immediate Specialist Referral

• Age <60 years (mandatory referral). 1, 3, 6
• Peripheral inflammatory arthritis (synovitis of hands, wrists, knees). 1, 6
• Systemic constitutional symptoms disproportionate to musculoskeletal complaints. 1, 6
• Low or normal inflammatory markers in a younger patient. 3, 6
• Inadequate response to appropriate glucocorticoid dosing (12.5–25 mg prednisone). 1
• High risk for glucocorticoid-related complications (uncontrolled diabetes, severe osteoporosis, active infection). 1

Comorbidity Assessment Before Starting Glucocorticoids

• Screen for hypertension, diabetes/glucose intolerance, cardiovascular disease, dyslipidemia. 1, 6
• Assess osteoporosis risk (especially in postmenopausal women—initiate calcium 1,200–1,500 mg daily, vitamin D 800–1,000 IU daily, and bisphosphonate prophylaxis). 1
• Evaluate for peptic ulcer disease, glaucoma/cataracts, chronic infections. 1, 6
• Female patients require more vigilant monitoring due to higher risk of glucocorticoid toxicity. 1, 6

Common Diagnostic Pitfalls to Avoid

• Do not require pelvic girdle involvement—some patients present with isolated bilateral shoulder pain, though a complete joint examination should always be performed. 6
• Do not dismiss the diagnosis based solely on normal ESR—up to 22% of genuine PMR cases have normal ESR, but CRP is usually elevated. 1, 5
• Do not start doses below 12.5 mg/day—subtherapeutic dosing leads to persistent symptoms and diagnostic uncertainty. 1
• Do not initiate glucocorticoids in patients under 60 without specialist evaluation—premature treatment may mask serious underlying conditions like malignancy or infection. 3
• Do not overlook the diagnostic delay—patients often undergo extensive imaging (CT scans, MRI, bone scans) and even hospitalization before diagnosis, with mean delays of 13 months reported. 8

Monitoring Schedule After Diagnosis

• Every 4–8 weeks during the first year to assess clinical response, inflammatory markers (ESR/CRP), and glucocorticoid adverse effects (blood pressure, weight, glucose, mood, infections). 1, 6
• Every 8–12 weeks during the second year and thereafter as needed during tapering. 1