Consistent with transcriptomics databases, proteins immune‐reactive for anti‐MXRA5 antibody were found both in the supernatant and sediment of centrifuged unconcentrated urine in CKD patients (samples 1‐3; Table S1), but not in healthy controls (samples 4 and 5; Table S1) (Fig. 2A and B). Here, MXRA5 is linked to chronic kidney disease.