title: Quantification of Dialytic Removal and Extracellular Calcium Mass Balance during a Weekly Cycle of Hemodialysis.
abstract: OBJECTIVE
  The removal of calcium during hemodialysis with low calcium concentration in dialysis fluid is generally slow, and the net absorption of calcium from dialysis fluid is often reported. The details of the calcium transport process during dialysis and calcium mass balance in the extracellular fluid, however, have not been fully studied.
  
  
  METHODS
  Weekly cycle of three dialysis sessions with interdialytic breaks of 2-2-3 days was monitored in 25 stable patients on maintenance hemodialysis with calcium concentration in dialysis fluid of 1.35 mmol/L. Total and ionic calcium were frequently measured in blood and dialysate. The volume of fluid compartments was measured by bioimpedance.
  
  
  RESULTS
  Weekly dialytic removal of 12.79 ± 8.71 mmol calcium was found in 17 patients, whereas 9.48 ± 8.07 mmol calcium was absorbed per week from dialysis fluid in 8 patients. Ionic calcium was generally absorbed from dialysis fluid, whereas complexed calcium (the difference of total and ionic calcium in dialysis fluid) was removed from the body. The concentration of total calcium in plasma increased slightly during dialysis. The mass of total and ionic calcium in extracellular fluid decreased during dialysis in patients with the dialytic removal of calcium from the body and did not change in patients with the absorption of calcium from dialysis fluid.
  
  
  CONCLUSIONS
  We conclude that about one third of patients on dialysis with calcium 1.35 mmol/L in dialysis fluid may absorb calcium from dialysis fluid and therefore individual prescriptions of calcium concentration in dialysis fluid should be considered for such patients.
authors.affiliation: Department for Mathematical Modelling of Physiological Processes, Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Waniewski
authors.affiliation: Department for Mathematical Modelling of Physiological Processes, Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Malgorzata
authors.identifier: http://orcid.org/0000-0001-8741-7930
authors.initials: M
authors.lastname: Debowska
authors.affiliation: Department of Physical Therapy and Rehabilitation, Medical University of Lublin, Lublin, Poland.
authors.forename: Alicja
authors.initials: A
authors.lastname: Wojcik-Zaluska
authors.affiliation: Department of Nephrology, Medical University of Lublin, Lublin, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Ksiazek
authors.affiliation: Department of Nephrology, Medical University of Lublin, Lublin, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zaluska
mesh_terms: D000368:Aged; D001692:Biological Transport; D002118:Calcium / Q000097:blood*; D015314:Dialysis Solutions; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis
chemical_list: D015314:Dialysis Solutions; D002118:Calcium