Fernandez-Martin JL, et al. - Researchers determined the impact of a 2- (midweek) or 3-day (post-weekend) dialysis interval for blood withdrawal on serum levels of chronic kidney disease-mineral and bone disorder (CKD-MBD) biomarkers and their relation to mortality risk in an analysis of the Current management of secondary hyperparathyroidism: a multicentre observational study (COSMOS). Based on midweek or post-weekend blood collection, the COSMOS cohort (6797 patients, CKD Stage 5D) was divided into two groups. Difference was noted in the midweek and post-weekend serum phosphate levels and their target ranges related to the lowest mortality risk. When recommending optimal target ranges for serum phosphate and therapeutic strategies for phosphate control, taking into account the timing of blood withdrawal in clinical guidelines was advised.