POSTN and focal segmental glomerulosclerosis: Periostin is mainly expressed in the areas of mesangial hyperplasia and interstitial fibrosis. Periostin mRNA is significantly increased in the pathological tissues of lupus nephritis and focal segmental glomerulosclerosis. Besides, it has an increasing trend in minimal change nephrotic syndrome and membranous nephropathy and IgA nephropathy, and the difference is not statistically significant. Periosin mRNA is negatively correlated with eGFR in patients with nephrotic syndrome, and has no correlation with proteinuria and age, indicating that it can be used as a biomarker.