Systemic Lupus Erythematosus

Autoimmune inflammatory condition caused by antibody-antigen deposition in various tissues.

H&P: Young women, blacks, hispanics, asians
Dx: DOPAMINe RASH 4 of 11 criteria, rule out 2° causes (drug-induced lupus SHIPP: sulfonamides, hydralazine, isoniazid, phenytoin, procainamide). Best screening test is ANA (98% sensitivity), most specific are anti ds-DNA, anti-Sm. Complement C3 and C4 levels can also be low, especially during acute flares.
Tx: NSAIDs for arthritis and mild serositis; hydroxychloroquine for skin and renal disease; for moderate to severe disease, use corticosteroids or anti B cell biologics; for acute flares, use steroid tapers. Test for anti-SSA in patients thinking about getting pregnant, as this antibody can cross the placenta and cause neonatal lupus and complete heart block. If patient has anti-phospholipid antibody syndrome, they need lifelong warfarin.

Rheumatoid Arthritis

H&P: middle aged women, HLA-DR4 serotype; morning stiffness that lasts > 30 min and improves with activity
Dx: 4 criteria for 6+ weeks. 3 or more joints (PIP, MCP, wrist, elbow, knee, ankle); symmetrical joint synovial hypertrophy with cartilage loss and osteoporosis on xray; elevated CRP, ESR (sensitive, not specific), rheumatoid factor (75% sensitive), or anti-CCP (most specific); inflammatory synovial fluid on joint aspiration; rheumatoid skin nodules (elbow most common).
Tx: NSAIDs and PT; Sulfasalazine, Hydroxychloroquine, or Glucocorticoids for milds disease; Methotrexate, anti-TNF biologics, or corticosteroids for moderate-severe disease; anti-TNF biologics AND corticosteroids for severe disease. Avoid methotrexate in patients with HIV, liver disease, ILD, renal disease, pregnancy, or bone marrow suppression; avoid anti-TNF in patients with TB.