Certain embodiments of the invention relate to means and methods for the diagnosis of a renal disease, particularly to differential diagnosis. Renal diseases of particular interest in the context of the invention are IgA-nephropathy, membranous glomerulonephritis (MGN), minimal-change-disease (MCD), focal segemental glomerulosclerosis (FSGS), and diabetic nephropathy. Particularly, the method comprises (a) measuring the presence or the absence of a polypeptide marker in a urine sample, wherein the polypeptide marker is selected from the group of polypeptide markers shown in tables 1 to 22, and (b) comparing the probability of the presence of this marker in a disease patient to the probability of the presence of this marker in a control patient, wherein the individual probabilities are as indicated in the tables, and wherein (c1) if the probability of the presence of this marker in a disease patient is higher than the probability of the presence of this marker in a control patient, the presence of this marker is indicative for a higher probability of having the disease, or (c2) if the probability of the presence of this marker in a disease patient is lower than the probability of the presence of this marker in a control patient, the absence of the marker is indicative for a higher probability of having the disease.