From the Guidelines
To monitor a patient with Rheumatoid Arthritis (RA), a complete blood count (CBC), liver function tests, and kidney function tests (creatinine, BUN) should be ordered regularly, with the frequency of testing depending on the medication regimen and disease stability, as recommended by the 2015 American College of Rheumatology guideline 1. The choice of laboratory tests is guided by the need to monitor disease activity, assess for potential side effects of medications, and evaluate the patient's overall health status.
- Key laboratory tests for RA patients include:
- Complete blood count (CBC) to assess for anemia and monitor white blood cell counts, especially in patients on immunosuppressive medications
- Liver function tests to monitor for medication side effects, particularly with methotrexate, leflunomide, and other disease-modifying antirheumatic drugs (DMARDs) 1
- Kidney function tests (creatinine, BUN) to monitor for medication side effects and assess renal function
- Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) to evaluate disease activity and response to treatment
- Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies for diagnosis and sometimes for monitoring disease progression The frequency of testing typically ranges from monthly to quarterly, depending on the medication regimen and disease stability, with more frequent monitoring recommended within the first 3 months of therapy or after increasing the dose 1. For example, patients on methotrexate should have CBC, liver enzymes, and creatinine monitored every 1-3 months, with initially more frequent assessments 1. Additionally, lipid profiles should be checked periodically as rheumatoid arthritis increases cardiovascular risk. It is essential to consider the individual patient's needs and adjust the monitoring schedule accordingly, taking into account factors such as comorbidities, abnormal laboratory results, and multiple therapies, which may require more frequent laboratory testing 1.
From the Research
Laboratory Tests for Rheumatoid Arthritis (RA)
To monitor a patient with Rheumatoid Arthritis (RA), several laboratory tests can be ordered. These tests include:
- Erythrocyte sedimentation rate (ESR) 2, 3, 4, 5, 6
- C-reactive protein (CRP) 2, 3, 4, 5, 6
- Rheumatoid factor 2
- Anticyclic citrullinated peptide (anti-CCP) antibodies 2
- Fibrinogen 3
Comparison of Laboratory Tests
Studies have compared the usefulness of different laboratory tests in monitoring RA. For example:
- CRP was found to be more informative than ESR in assessing radiographic changes in RA 4
- Fibrinogen was found to be superior to ESR in measuring disease activity in RA 3
- CRP was found to be a better measure of disease activity than ESR when discordance occurred between the two tests 5
Limitations of Laboratory Tests
It is important to note that laboratory tests have limitations in diagnosing and managing RA. For example: