What is C3 Complement?
Complement C3 is also known as simply C3. This protein is a genetic part of the immune system. People with low levels of C3 may contract bacterial infections more often. C3 measurements on blood tests can be used to support or refute a particular diagnosis – specifically infectious conditions, inflammation and edema. C3 and C4 testing are ordered simultaneously so doctors can read each value and relative values of the pair.

C3 Complement levels may measure lower than normal if there is a genetic condition not associated with any disease process – but the hereditary condition can cause recurring infections.

Normal Value Range

  • Negative Pregnancy Adult: 83 to 177 mg/dL or 0.83 to 1.77 g/L
  • Pregnancy Trimester One: 44 to 116 mg/dL or 0.44 to 1.16 g/L
  • Pregnancy Trimester Two: 58 to 118 mg/dL or 0.58 to 1.18 g/L
  • Pregnancy Trimester Three: 60 to 126 mg/dL or 0.6 to 1.26 g/L

Lower than normal C3 can be linked to lupus nephritis, poststreptococcal GN (acute), infancy, hereditary deficiency, lupus erythematosus (systemic), sepsis from massive tissue injury or viremia.

High levels can also be measured. Biliary obstruction, therapy with corticosteroids, nephrotic syndrome and inflammation can all be possible causes.

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