POSTN and chronic kidney disease: The Polish research group of Mizerska-Wasiak et al. failed to replicate the previously mentioned results of Hwang et al. [51], but their analysis of a 20 patient cohort with IgAN may have been confounded by the fact that the analysis was performed in a pediatric population (3 to 17 year old subjects), by the lack of measurement of urinary periostin at baseline (kidney biopsy moment), and by the fact that the subjects had low severity CKD stage G1 to G2 [54].