C3/C4

Pathology category

Biochemistry

Code

C34

Referral code

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Test information

Measurement of serum complement C3 and C4 is useful in the diagnosis and monitoring of immune complex disease eg SLE. Indicated in investigation of renal/joint/connective tissue disorders (especially SLE). Complement concentrations are acute phase proteins and are therefore increased in inflammatory conditions hence concentrations may be normal, despite complement consumption, in some inflammatory and infective disorders.

Guidelines

Pre-analytical

Reference range

C3: 0.9 – 1.8 g/L

C4: 0.1 – 0.4 g/L

Tube type

Tube type info

Adults: 5ml Serum SST (gold top)

Paediatrics: 0.5ml lithium/heparin (orange top)

Special requirements

Minimum volume

Adults: 1 ml

Paediatrics: 0.3 ml

Assay frequency

Run daily at local laboratory

TAT Inpatient (urgent)

TAT Inpatient

48 hrs

TAT GP/Outpatient

48 hrs

Referral lab

Local, Clinical Biochemistry