SERPINA1 and acute kidney injury: Direct comparison of the two marker patterns revealed identity of the SERPINA1‐derived peptide SERPINA1[Thr363‐Phe376], whereas the COL1A1‐, B2M‐, and FGA‐derived AKI peptide markers in MALDI are for the most part smaller fragments of the previously described CE‐MS‐identified peptide markers.