CST3 and chronic kidney disease: While the study by Moreira et al. raises more questions than it answers due to the size and study design, given the role of cystatin C as an established tool for the assessment of kidney function in the general and CKD population as well as an additive marker of cardiovascular risk assessment, further large prospective studies in the PD population are warranted in order to delineate whether cystatin C will have a role in the management of the PD population.