S100A8 and kidney disorder: Although in our study patients with renal disease had higher levels of S100A8/A9 in serum than the control group, and similar results were found in the group of IgAV patients with gastrointestinal involvement, we found no differences between patients with active disease when we were comparing those with renal disease with ones without it, similar to the comparison of those with or without gastrointestinal or joint involvement.