title: Phosphorus dynamics during hemodialysis.
abstract: We studied phosphorus (P) dynamics and its relation to urea dynamics in a wide range of dialyses by measuring predialysis and postdialysis serum P levels and all removed P and urea in dialysate during 455 hemodialyses. Dialyses were performed at different frequencies (range 3-6 treatments/wk); duration of dialysis (t) (range 80-560 minutes), varied blood and dialysate flow, and with high-flux and low-flux membranes. Kt/V-P, Kt/V-urea, weekly removal of P-and urea and removal volumes (Vr) and their relationships to varying dialyses, and predialysis concentrations, and protein catabolic rates were studied in linear and multiple regression analyses. A weekly dialysis time of > 30 hours was needed to maintain serum P concentration normal without the use of phosphate binders. Vr-P as a percentage of body weight was dependent on predialysis serum P and increased steeply as predialysis serum P decreased and dialysis time was prolonged. There was no relationship between Vr-urea and Vr-P. Phosphorus removal per week was mainly dependent on weekly frequency, and time on dialysis and > 38 h/wk were necessary to remove the recommended P intake. Phosphorus shows highly variable dynamics during dialysis. The body maintains extracellular P concentration by releasing P from large compartments when the dialysis time is prolonged and the serum concentration of P decreases during dialysis. Vr-P shows huge variation between patients and in an individual patient, depending on predialysis serum P. Kt/V is inaccurate in describing P removal. To remove P efficiently, it is most important to perform long and more frequent hemodialysis.
authors.affiliation: Hines VA/Loyola University Chicago, Chicago, Illinois, USA. carl.kjellstrand@gmail.com
authors.forename: Carl M
authors.initials: CM
authors.lastname: Kjellstrand
authors.forename: Todd S
authors.initials: TS
authors.lastname: Ing
authors.forename: Per T
authors.initials: PT
authors.lastname: Kjellstrand
authors.forename: Ingegerd
authors.initials: I
authors.lastname: Odar-Cederlof
authors.forename: Chris R B
authors.initials: CR
authors.lastname: Lagg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000378:metabolism* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000097:blood / Q000378:metabolism*; D006435:Renal Dialysis / Q000379:methods*; D055815:Young Adult
chemical_list: D010710:Phosphates