How is SLE diagnosed?

How is SLE diagnosed?

• A. Positive ANA
• B. Elevated ESR
• C. Negative ANA
• D. Rheumatoid factor positive

Answer: (A)

A positive ANA is the best initial clue because SLE almost always shows ANA positivity, making it a highly sensitive screening test. This finding supports moving on to more disease-specific tests (like anti-dsDNA and anti-Smith) and to evaluate clinical features that together establish the diagnosis. However, ANA is not specific to SLE—many other autoimmune diseases and some healthy individuals can have a positive ANA—so it cannot by itself confirm the disease. A negative ANA would make SLE unlikely in most cases, though rare ANA-negative presentations exist. Elevated ESR is nonspecific and can occur in many inflammatory states, and rheumatoid factor is not specific for SLE and can be positive in other conditions. Thus, a positive ANA best fits the role of an initial diagnostic signal for SLE.

A positive ANA is the best initial clue because SLE almost always shows ANA positivity, making it a highly sensitive screening test. This finding supports moving on to more disease-specific tests (like anti-dsDNA and anti-Smith) and to evaluate clinical features that together establish the diagnosis. However, ANA is not specific to SLE—many other autoimmune diseases and some healthy individuals can have a positive ANA—so it cannot by itself confirm the disease. A negative ANA would make SLE unlikely in most cases, though rare ANA-negative presentations exist. Elevated ESR is nonspecific and can occur in many inflammatory states, and rheumatoid factor is not specific for SLE and can be positive in other conditions. Thus, a positive ANA best fits the role of an initial diagnostic signal for SLE.