Complement deficiency

Key Information

Appropriate Tests

 

Complement CH50 or CH100.

Further testing in specialised laboratory, consult pathologist.

Congenital (primary) deficiency

Complement CH50 or CH100 levels frequently reduced.

  • SLE-like syndromes

Complement components C1q and C2, Complement components C3 and C4, Complement component C4 allotypes.

  • Recurrent infection
C3 (See Complement components C3 and C4). C3 receptor.
  • Recurrent neisserial infection
Complement components C5, C6, C7, C8, C9.
  • Angioedema

 

  • Serum mannose binding lectin

 

  • Mannose binding lectin genotyping

 

Acquired deficiency

Complement CH50 or CH100 levels frequently reduced.

  • SLE

Complement components C3 and C4 may be reduced.

  • Gram-negative (endotoxic) shock

C3 reduced, C4 normal; tests rarely indicated.

  • Serum sickness

Complement components C3 and C4 reduced.

  • Subacute bacterial endocarditis

See Endocarditis (infective)

Complement components C3 and C4 may be reduced; tests rarely indicated.

  • Mesangiocapillary glomerulonephritis

See Glomerulonephritis (GN)

C3 reduced. C3 Nephritic factor.

  • Partial lipodystrophy

C3 reduced. C3 Nephritic factor.