Clinical
Indications |
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C4 is usually measured in
investigation of patients with renal disease, joint disease and multi-system disorders
with evidence of vasculitis; low concentrations imply an immunological basis for the
symptoms. C4 (and C3) levels may be useful in patients with recurrent infections with
normal or raised immunoglobulin levels, since genetic and acquired defects sometimes
present as immunodeficiency (CH50 analysis also required in such cases).
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