In this short, I break down the five SLE (lupus) questions that USMLE loves to ask across Step 1, Step 2, and Step 3—and I save the hardest one for the end, like always. I walk you through the classic presentation (young woman with malar rash, joint pain, fatigue) and the single best “best initial test” answer: ANA. A lot of students want to jump straight to anti-dsDNA or anti-Smith, but ANA is your screen because it’s >95% sensitive—if it’s negative, lupus is basically ruled out. Then I hit the high-yield antibody distinctions the exam tests: anti-Smith is the most specific (positive = lupus, period), while anti-dsDNA tracks disease activity, especially lupus nephritis. For renal disease, I focus on Class IV diffuse proliferative glomerulonephritis—the most common and most severe—with “wire loop” subendothelial deposits on biopsy, treated with steroids plus mycophenolate or cyclophosphamide. I also cover antiphospholipid syndrome (miscarriages/clots → lupus anticoagulant, anticardiolipin, anti–β2 glycoprotein; treat with heparin + aspirin) and end with drug-induced lupus: think anti-histone antibodies and classic culprit meds—then stop the drug and it reverses.