Serum phosphate optimal timing and range associated with patients survival in haemodialysis: The COSMOS study

José L. Fernández-Martín, Adriana Dusso, Pablo Martínez-Camblor, Maria P. Dionisi, Jürgen Floege, Markus Ketteler, Gérard London, Francesco Locatelli, José L. Górriz, Boleslaw Rutkowski, Willem Jan Bos, Christian Tielemans, Pierre Yves Martin, Rudolf P. Wüthrich, Drasko Pavlovic, Miha Benedik, Diego Rodríguez-Puyol, Juan J. Carrero, Carmine Zoccali, Jorge B. Cannata-AndíaAdrian Covic, Aníbal Ferreira, David Goldsmith, Reinhard Kramar, Dimitrios Memmos, Judit Nagy, Vladimir Teplan, Dierik Verbeelen, José Luis Motellón, Matthew Turner, Julien Chaussy, Bart Molemans, Wal Zani, Dylan Rosser, Bastian Dehmel, Bruno Fouqueray, Brian Bradbury, John Acquavella, Jennifer Hollowell, Dave Carter, Phil Holland, Ana Baños, Caroline Mattin, Cathy Critchlow, Joseph Kim, Charlotte Lewis, Antonia Panayi, Margit Hemetsberger, Stephen Croft, Philippe Jaeger, Prisca Muehlebach, Jane Blackburn, Esther Zumsteg, Silvia Rodríguez, Angel Pérez, Pau Faner, Irantzu Izco, Susana Traseira, Carmen Castro, Javier Moreno, David Calle, Francesca Pieraccini

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17 Scopus citations


Background. Serum phosphate is a key parameter in the management of chronic kidney disease-mineral and bone disorder (CKD-MBD). The timing of phosphate measurement is not standardized in the current guidelines. Since the optimal range of these biomarkers may vary depending on the duration of the interdialytic interval, in this analysis of the Current management of secondary hyperparathyroidism: a multicentre observational study (COSMOS), we assessed the influence of a 2- (midweek) or 3-day (post-weekend) dialysis interval for blood withdrawal on serum levels of CKD-MBD biomarkers and their association with mortality risk. Methods. The COSMOS cohort (6797 patients, CKD Stage 5D) was divided into two groups depending upon midweek or post-weekend blood collection. Univariate and multivariate Cox's models adjusted hazard ratios (HRs) by demographics and comorbidities, treatments and biochemical parameters from a patient/centre database collected at baseline and every 6 months for 3 years. Results. There were no differences in serum calcium or parathyroid hormone levels between midweek and post-weekend patients. However, in post-weekend patients, the mean serum phosphate levels were higher compared with midweek patients (5.5 ± 1.4 versus 5.2 ± 1.4 mg/dL, P < 0.001). Also, the range of serum phosphate with the lowest mortality risk [HR ≤ 1.1; midweek: 3.5-4.9 mg/dL (95% confidence interval, CI: 2.9-5.2 mg/dL); post-weekend: 3.8-5.7 mg/dL (95% CI: 3.0-6.4 mg/dL)] showed significant differences in the upper limit (P = 0.021). Conclusion. Midweek and post-weekend serum phosphate levels and their target ranges associated with the lowest mortality risk differ. Thus, clinical guidelines should consider the timing of blood withdrawal when recommending optimal target ranges for serum phosphate and therapeutic strategies for phosphate control.

Original languageEnglish
Pages (from-to)673-681
Number of pages9
JournalNephrology Dialysis Transplantation
Issue number4
StatePublished - Apr 1 2019


  • calcaemia
  • chronic haemodialysis
  • epidemiology
  • hyperparathyroidism
  • phosphataemia


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