Specimen requirement

Adult patient:

  Heparin gel tube

Minimum blood volume: 5 mL

Paediatric patient:

Paediatric heparin tube

Number of vials: 1

Minimum blood volume: 1.3 mL

Authorisation code required

No

24 Hr available service

Yes

(Call extension: 3353 for express result)

Method

Immunoassay

Reference interval

0.10 - 0.40 g/L

(Source: from manufacturer's kit insert)

Clinical indication

Monitoring activity of immune complex mediated disease, e.g. SLE, glomerulonephritis, cryoglobulinaemia.

Detection of primary deficiency of C3 or C4 (rare)

Result interpretation

Reduced C4 with or without reduced C3: activation by classical pathway (e.g. SLE, immune complex disease)

Reduced C3 with normal C4: activation by the alternative pathway (e.g. sepsis, endotoxin)

Raised C3 and / or C4: acute phase response

Measurement of uncertainty

See table.

Frequency of measurement

Daily