What are the key clinical features and laboratory tests to consider when diagnosing Systemic Lupus Erythematosus (SLE) in primary care?

Key clinical features to consider when diagnosing systemic lupus erythematosus (SLE) in primary care include a combination of constitutional symptoms such as fatigue, fever, and weight loss, alongside more specific manifestations like malar rash, photosensitivity, oral ulcers, arthritis (typically non-erosive), serositis (pleuritis or pericarditis), renal involvement (proteinuria or haematuria), neurological symptoms (seizures or psychosis), and haematological abnormalities (anaemia, leukopenia, or thrombocytopenia) ¹. These features often present variably and may be subtle, requiring a high index of suspicion in patients with multisystem complaints (Pramanik, 2014).

Laboratory tests essential for initial assessment in primary care include antinuclear antibody (ANA) testing, which is highly sensitive for SLE but not specific, serving as a useful screening tool ¹. If ANA is positive, further specific autoantibodies such as anti-double stranded DNA (anti-dsDNA) and anti-Smith antibodies should be considered to support diagnosis and assess disease activity (Pramanik, 2014). Additionally, routine blood tests including full blood count, renal function, urinalysis for proteinuria or haematuria, and inflammatory markers (ESR, CRP) help identify organ involvement and systemic inflammation ¹. Complement levels (C3, C4) may also be reduced in active disease (Pramanik, 2014).

In primary care, the diagnosis of SLE relies on recognizing the constellation of clinical features combined with targeted laboratory investigations to guide timely referral to rheumatology for confirmation and management ¹. Early identification is critical due to the potential for multisystem involvement and morbidity (Pramanik, 2014).