see also:

• arthritis - clinical patterns
• glomerulonephritis (GN)

• complement testing is useless for screening for cause of arthritis but is often used to monitor disease activity in patients with SLE
• decreased levels of complement arise from immune-complex disorders such as:
  • systemic lupus erythematosus (SLE)
  • selected forms of vasculitis (e.g., essential mixed cryoglobulinemia and rheumatoid vasculitis)
  • certain types of glomerulonephritis (GN)
  • inherited complement deficiencies