Even in these two proteinuria-matched groups, the IGFBP4 levels were significantly different; in the CKD control group, the mean IGFBP4 level was 737.4 ng/ml, whereas in the LN group the mean IGFBP4 level was 1477.6 ng/ml (p< 0.014), indicating that the increased IGFBP4 in LN was not a consequence or reflection of proteinuria. Here, IGFBP4 is linked to chronic kidney disease.