Imperial Collage Healthcare

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Complement, total alternative pathway


Lab Code : AP50


Test Background
The AP50 assay measures the ability of serum complement components to form membrane attack complex, which can be detected by ELISA. C3 and C4 levels must also be requested. The assay is used as a screening test for defects of individual components of the alternative and terminal pathways. It should not be used for monitoring complement consumption, instead request C3 and C4 levels.


Clinical Indications
Suspected complement deficiency Recurrent infections Recurrent Neisseria infections


Reference Range
50-125 % of normal


Sample Required
RST (rust top) Separate and freeze immediately Transport frozen


Sample Volume
5-10 mL (1 mL serum)


Turnaround Time
21 days


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