Polymyalgia Rheumatica Workup
Before initiating glucocorticoid therapy, obtain a comprehensive laboratory panel including inflammatory markers (ESR and/or CRP), rheumatoid factor and/or anti-CCP antibodies, complete blood count, glucose, creatinine, liver function tests, bone profile (calcium, alkaline phosphatase), and urinalysis to establish baseline values and exclude mimicking conditions. 1, 2, 3
Core Laboratory Tests (Mandatory)
- Inflammatory markers: ESR and/or CRP are essential, though 14% of PMR patients may have normal values at diagnosis 4. High ESR (>40 mm/1st hour) is associated with increased relapse risk and may guide initial treatment decisions 1, 3
- Autoantibody testing: Rheumatoid factor and/or anti-cyclic citrullinated peptide antibodies (ACPA) to exclude rheumatoid arthritis 1, 2, 3
- Complete blood count: Assess for anemia and other causes of inflammation 1, 3
- Metabolic panel: Glucose, creatinine, and liver function tests establish baseline before glucocorticoid therapy 1, 3
- Bone profile: Calcium and alkaline phosphatase to assess bone health prior to steroid therapy 1, 3
- Urinalysis: Exclude other inflammatory or infectious conditions 1, 3
Additional Recommended Tests
- Protein electrophoresis: Exclude paraproteinemia which can mimic PMR 1, 3
- Thyroid stimulating hormone (TSH): Rule out thyroid disorders with similar presentations 1, 3
- Creatine kinase: Exclude myopathies and myositis 1, 3
- Vitamin D: Establish baseline before glucocorticoid therapy 1, 3
Extended Testing Based on Clinical Context
- Anti-nuclear antibodies (ANA) and anti-neutrophil cytoplasmic antibodies (ANCA): Consider when other autoimmune conditions are suspected based on atypical features 1, 3
- Tuberculosis testing: Required when immunosuppressive therapy is planned or in high-risk patients 1, 3
- Chest radiograph: Consider to exclude malignancy or other diagnoses at physician discretion 1, 3
Special Consideration for Normal Inflammatory Markers
If ESR and CRP are normal but clinical suspicion remains high, consider measuring serum amyloid A (SAA), which may be elevated when ESR and CRP are normal 4. Ultrasound demonstrating bilateral subdeltoid bursitis supports the diagnosis in these cases 4.
Comorbidity Assessment (Critical for Treatment Planning)
Document the following risk factors for glucocorticoid-related adverse events 1:
- Cardiovascular: Hypertension, cardiovascular disease, dyslipidemia 1, 2
- Metabolic: Diabetes, glucose intolerance 1, 2
- Gastrointestinal: Peptic ulcer disease, NSAID co-medication 1
- Musculoskeletal: Osteoporosis, recent fractures 1, 2
- Ophthalmologic: Cataracts, glaucoma risk factors 1
- Infectious: Chronic or recurrent infections 1
Female sex is associated with higher risk of glucocorticoid side effects and potentially longer treatment duration 1, 2.
Indications for Specialist Referral
Refer to rheumatology for 1, 2:
- Atypical presentations: Peripheral inflammatory arthritis, systemic symptoms, age <60 years 1, 2
- Low or normal inflammatory markers despite typical clinical features 1, 2
- High risk of therapy-related side effects based on comorbidity profile 1
- Inadequate response to glucocorticoids within 2 weeks 1
- Relapse or requirement for prolonged therapy 1
Common Pitfalls to Avoid
- Do not delay treatment while awaiting specialist consultation if diagnosis is clinically evident, as prompt glucocorticoid therapy prevents morbidity 5, 6
- Do not assume normal ESR/CRP excludes PMR—14% of patients have normal values at diagnosis 4
- Do not overlook giant cell arteritis symptoms (new headache, visual changes, jaw claudication), which require immediate high-dose glucocorticoids to prevent blindness 6, 7, 8
- Do not use NSAIDs as primary therapy—glucocorticoids are strongly recommended as first-line treatment 1