In this post, I link to and excerpt from The Curbsiders Episode #399 Wisely Ordering Autoantibodies*.
*Carroll MB, Garbitelli BC, Williams PN, Watto MF. “#399 Wisely Ordering Autoantibodies – ACP IM2023”. The Curbsiders Internal Medicine Podcast. thecurbsiders.com/category/curbsiders-podcast June 12, 2023.
All that follows is from the above outstanding resource.
Wisely Ordering Autoantibodies Pearls
- The American College of Rheumatology (ACR) 2010 guidelines for RA are a helpful starting point (Aletaha 2010).
- Dr. Carroll’s recommended first line of tests for considering rheumatoid arthritis diagnosis would be: ESR, CRP, rheumatoid factor, anti-CCP. If you’re thinking of Sjogren’s Syndrome, consider an anti-SSA/SSB antibody test and potentially pursuing a minor salivary gland biopsy. For Systemic Lupus Erythematosus, check ANA, anti-dsDNA and anti-Smith antibodies as well as complement levels (C3/C4), CBC with differential, BUN/Creatinine, and urine protein-creatinine ratio.
- When rheumatoid factor is severely elevated (ie: high 200s) that should make you consider HCV and HBV screening (Moll 2019).
- Rheumatologists want us to try to capture patients with inflammatory conditions early. For example, the rheumatology community is increasingly interested in identifying and treating patients in a ‘pre-RA’ state (Haville 2022). Ideally, we can treat these patients so they don’t develop the debilitating joint and lung damage that prior generations of patients have endured (Paul 2017).
- If a patient has a mildly elevated ANA titer with a speckled pattern, it is a common finding. Studies show between 15-30% of adult females can have a mildly positive ANA. (Tan 1997, Blumenthal 2002, Parks 2014, Slater 1996).
Initial Evaluation & Testing
Dr. Carroll’s recommended first line of tests for considering rheumatoid arthritis diagnosis would be: ESR, CRP, rheumatoid factor, anti-CCP. If you’re thinking of Sjogren’s Syndrome, consider an anti-SSA/SSB antibody test and potentially pursuing a minor salivary gland biopsy. For Systemic Lupus Erythematosus, check ANA, anti-dsDNA and anti-Smith antibodies as well as complement levels (C3/C4), CBC with differential, BUN/Creatinine, and urine protein-creatinine ratio (Syed 1996, Wielosz 2020). Metabolic panels can be helpful in terms of determining treatments, per Dr. Carroll.
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