CONSULT ROUNDS: Normal Complements and Infection associated GN

Post infectious GN usually has been associated with hypocomplementemia.  There are certain situations where the complements can be normal and you still have an "infection" associated GN.
A nice trail by history revealed an old article from 1970s from NEJM. They studied 11 patients with visceral abscesses in whom renal injury was present. All biopsies showed diffuse proliferative GN.  7/11 had normal complements and 4/11 had low complements. No endocarditis was present and no cryoglobulins. The course of the renal disease closely related to the resolution of the abscesses. Hence this is a very important cause of normal complement associated post infectious or "infection associated immune complex disease"

To take this topic further. It is not uncommon to see normal complements in early classic post infectious GN. Clinical suspicion and history can sometimes be more important than lab tests. Take a look at the second article listed below which is also from 1970s regarding early complements levels in PIGN.

A new entity called Post infectious Ig A variant of PIGN can also lead to normal complements and similar picture. In this case, one sees mesangial deposits of IgA in a PIGN setting with neutrophils; usually in DMII, elderly and Staph infections.  Check out an NDT article below regarding this entity.

Ref:
http://www.ncbi.nlm.nih.gov/pubmed/1272347
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1607211/
http://ndtplus.oxfordjournals.org/content/4/3/181.short?rss=1