title: Phosphate kinetics during different dialysis modalities.
abstract: BACKGROUND
  An abnormal serum phosphate concentration is common in acute renal failure patients, with a reported incidence of 65-80%. Phosphate removal and kinetics during intermittent hemodialysis (IHD) have been investigated, but there is no information on its kinetics during slow low-efficiency dialysis (SLED) and continuous renal replacement therapy (CRRT).
  
  
  METHODS
  Eight IHD, 8 SLED, and 10 continuous venovenous hemofiltration (CVVH) patients with a residual renal clearance of <4.0 ml/min were studied during a single treatment to evaluate phosphate removal and kinetics. CVVH was studied the first 24 h after initiation. Dialysis/replacement fluid contained no phosphate. Kt/V, clearance of urea (Ku), inorganic phosphate (Kp) and solute removal was determined by direct dialysate quantification (DDQ).
  
  
  RESULTS
  Kp recorded with the three techniques were: IHD, 126.9 +/- 18.4 ml/min; SLED, 58.0 +/- 15.8 ml/min, and CVVH, 31.5 +/- 6.0 ml/min. However, in shorter dialysis treatment the total removal of phosphate was significantly lower than in longer dialysis (IHD, 29.9 +/- 7.7 mmol; SLED, 37.6 +/- 9.6 mmol; CVVH, 66.7 +/- 18.9 mmol, p = 0.001). The duration of treatment is the only factor determining phosphate removal (r = 0.7, p < 0.0001 by linear correlation model). Like IHD, phosphate kinetics during SLED could not be explained by the two-pool kinetic model, and the rebound of phosphate extended beyond 1 h after dialysis. Rebound, however, is less marked than in short dialysis.
  
  
  CONCLUSIONS
  These results are reliable evidence about amount of phosphate removal and behavior of intradialytic phosphate kinetics in renal failure patients undergoing different dialysis modalities. These data will help clinicians plan phosphate supplementation and treatment intensity.
authors.affiliation: Department of Nephrology, Dialysis and Transplantation, St Bortolo Hospital, Vicenza, Italy.
authors.forename: Ranistha
authors.initials: R
authors.lastname: Ratanarat
authors.forename: Alessandra
authors.initials: A
authors.lastname: Brendolan
authors.forename: Gopel
authors.initials: G
authors.lastname: Volker
authors.forename: Monica
authors.initials: M
authors.lastname: Bonello
authors.forename: Gabriella
authors.initials: G
authors.lastname: Salvatori
authors.forename: Emilio
authors.initials: E
authors.lastname: Andrikos
authors.forename: Asuman
authors.initials: A
authors.lastname: Yavuz
authors.forename: Carlo
authors.initials: C
authors.lastname: Crepaldi
authors.forename: Claudio
authors.initials: C
authors.lastname: Ronco
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000097:blood / Q000493:pharmacokinetics*; D011446:Prospective Studies; D006435:Renal Dialysis / Q000295:instrumentation / Q000379:methods*; D017582:Renal Replacement Therapy / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors; D014508:Urea / Q000097:blood / Q000378:metabolism
chemical_list: D010710:Phosphates; D014508:Urea