In a patient over 50 with proximal shoulder and hip pain and morning stiffness suggestive of polymyalgia rheumatica, which laboratory tests and imaging should be obtained to screen for the disease and rule out giant‑cell arteritis?

Laboratory and Imaging Workup for Polymyalgia Rheumatica

In a patient over 50 with proximal shoulder and hip pain and morning stiffness suggestive of polymyalgia rheumatica, obtain ESR and/or CRP, complete blood count, rheumatoid factor and/or anti-CCP antibodies, comprehensive metabolic panel (glucose, creatinine, liver enzymes), bone profile (calcium, alkaline phosphatase), urinalysis, creatine kinase, and TSH to confirm inflammation, exclude mimicking conditions, and establish baseline organ function before glucocorticoid therapy. 1

Core Laboratory Panel

The European League Against Rheumatism recommends a standardized baseline laboratory dataset for all suspected PMR cases: 1

• Inflammatory markers: ESR and/or CRP are essential—ESR >40 mm/1st hour predicts higher relapse rates and may guide initial prednisone dosing toward the higher end of the 12.5-25 mg range 1, 2
• Autoantibodies: Rheumatoid factor and/or anti-cyclic citrullinated peptide antibodies (ACPA) to exclude rheumatoid arthritis 1, 3
• Complete blood count: Assess for anemia of chronic inflammation and exclude other inflammatory or hematologic conditions 1
• Comprehensive metabolic panel: Glucose, creatinine, and liver function tests establish baseline before glucocorticoid therapy and screen for diabetes, renal disease, and hepatic dysfunction 1, 3
• Bone profile: Calcium and alkaline phosphatase assess bone health before initiating steroids 1
• Urinalysis: Excludes renal or infectious causes of systemic inflammation 1

Additional Screening Tests

• Creatine kinase (CK): Must be normal in PMR—elevated CK (median ~2,650 IU/L in myositis) indicates inflammatory myositis rather than PMR 1, 4, 5
• Thyroid-stimulating hormone (TSH): Rules out thyroid disorders that mimic PMR symptoms 1
• Protein electrophoresis: Excludes paraproteinemia, which can present with similar musculoskeletal complaints 1
• Vitamin D: Establishes baseline before prolonged glucocorticoid therapy 1

Giant Cell Arteritis Screening

Approximately 20% of PMR patients develop concurrent giant cell arteritis, which requires immediate high-dose glucocorticoids (40-60 mg prednisone daily) to prevent irreversible vision loss. 1, 4, 5

Screen every PMR patient for GCA features at presentation and during follow-up: 6, 1

• New-onset headache (sensitivity 67%, specificity 58%) 6
• Jaw claudication (sensitivity 38%, specificity 92%, positive LR 7.24)—the most specific symptom 6
• Visual disturbances: Transient vision loss, diplopia, or permanent vision loss 6, 1
• Scalp tenderness (sensitivity 39%, specificity 79%) 6
• Temporal artery abnormalities: Tenderness, reduced pulse, or nodularity 6

If any GCA features are present, initiate prednisone 40-60 mg daily immediately and arrange urgent temporal artery ultrasound or biopsy. 1, 4, 5

Extended Testing for Atypical Presentations

Do not routinely order ANA or ANCA in typical PMR presentations. 1 Reserve these tests for atypical scenarios requiring specialist referral: 1

• Age <60 years (especially <50 years)
• Peripheral inflammatory arthritis involving hands, wrists, or feet
• Constitutional symptoms: Unexplained weight loss, fever, or organ involvement beyond typical PMR
• Low or normal inflammatory markers despite active symptoms
• Inadequate response to appropriate glucocorticoid dosing (12.5-25 mg prednisone) within 2 weeks

Additional testing in these atypical cases: 1

• ANA and ANCA: Screen for systemic lupus erythematosus, vasculitis, or other connective tissue diseases
• Tuberculosis testing: Required before immunosuppressive therapy or in high-risk patients
• Chest radiograph: Excludes malignancy or alternative thoracic diagnoses

Imaging Considerations

While not required for diagnosis in typical cases, imaging may support the diagnosis or exclude alternatives: 5, 7

• Ultrasound: Detects bilateral subdeltoid bursitis in 69% of PMR patients and can identify temporal artery wall thickening in GCA (specificity 78-100%) 5
• MRI or PET-CT: Reserved for atypical presentations or when large-vessel GCA is suspected 5, 7
• Chest radiograph: Excludes malignancy when constitutional symptoms are prominent 1

Pre-Treatment Comorbidity Assessment

Before initiating glucocorticoids, document baseline comorbidities that will require monitoring: 1, 3

• Cardiovascular: Blood pressure, lipid profile, history of cardiovascular disease
• Metabolic: Fasting glucose or HbA1c, screen for diabetes or impaired glucose tolerance
• Gastrointestinal: History of peptic ulcer disease
• Bone health: Osteoporosis risk factors, prior fractures
• Ophthalmologic: Glaucoma or cataract risk
• Infectious: Chronic or recurrent infections

Common Diagnostic Pitfalls

• Do not diagnose PMR if CK is elevated—this indicates myositis, not PMR 1, 4
• Do not miss GCA screening—jaw claudication has the highest positive likelihood ratio (7.24) and should trigger immediate high-dose steroids 6
• Do not order ANCA/ANA routinely—reserve for atypical presentations to avoid false-positive results and unnecessary specialist referrals 1
• Do not skip baseline glucose and bone profile—female patients have higher risk of glucocorticoid-induced osteoporosis and metabolic complications 1, 3
• Do not accept normal inflammatory markers as excluding PMR—a small subset has normal ESR/CRP, but this warrants specialist evaluation 1

Expected Response and Diagnostic Confirmation

• Dramatic clinical improvement within 1-2 weeks of prednisone 12.5-25 mg daily confirms the diagnosis 1, 4, 5
• Lack of substantial response within 2 weeks mandates dose escalation up to 25 mg daily or diagnostic reassessment 1
• Female sex, high baseline ESR (>40 mm/hr), and peripheral arthritis predict higher relapse rates and warrant more vigilant monitoring 1, 2