Synonyms

   3rd Component of Complement

Clinical Significance

   It is useful for Assessing disease activity in systemic lupus erythematosus (SLE) and Investigating an undetectable total complement (CH50) level.

Specimen

   Serum

Stability

   Refrigerated (preferred) : 7 days

   Frozen : 28 days

   Ambient : 72 hours

Reference Range

   0.9 – 1.8 g/L

Interpretation

   A decrease in C3 levels to the abnormal range is consistent with disease activation in systemic lupus erythematosus (SLE).