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Serological Flare in SLE — SCE Rheumatology MCQ

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ModerateSLE & Antiphospholipid SyndromeSerological Flare in SLESCE Rheumatology

A 30-year-old woman with established SLE attends routine follow-up. She is asymptomatic and examination is normal. Her C3 has fallen from within the reference range to 0.45 g/L and C4 to 0.08 g/L; anti-dsDNA has risen from 35 to 180 IU/mL. Full blood count, creatinine, liver profile, urinalysis and urine protein:creatinine ratio are normal. The serological results are confirmed on a repeat sample. What is the best interpretation?

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Correct answer: E — A serologically active, clinically quiescent SLE pattern associated with increased risk of a subsequent clinical flare

The combination of newly reduced C3 and C4 with rising anti-dsDNA, in the absence of clinical or organ-specific activity, represents isolated serological activity—a serologically active, clinically quiescent pattern. Such serological activity is associated with a higher risk of subsequent flare and warrants careful clinical and renal surveillance, but it does not prove that a clinical flare is imminent or justify treatment escalation solely on these results. Active nephritis is not established because creatinine, urinalysis and protein excretion are normal. Hereditary complement deficiency would usually be longstanding and does not explain the rising anti-dsDNA titre. Normal liver tests and confirmation on repeat sampling make reduced hepatic synthesis and analytical variation unlikely.

Reference: Parodis I et al. Practical insights for the clinical implementation of the EULAR recommendations for patients with systemic lupus erythematosus, sections 8.1 and 11.1. RMD Open. 2025;11:e006210. https://ard.bmj.com/content/78/6/736