AIM: We investigated the handling of phosphate by end-stage kidneys and the contribution of residual renal function (RRF) to phosphate homeostasis in haemodialysis patients. METHODS: Blood and 24 h urinary specimens were obtained from 79 consecutive chronic haemodialysis patients with a urinary output greater than 100 mL/day. Thirty-five patients with a glomerular filtration rate (GFR) ≥ 3.0 mL/min were included as group A, and 44 patients with GFR < 3.0 mL/min as group B. Additionally, the whole dialysed fluids during a session of haemodialysis were collected from another nine patients. Concentrations of phosphate, creatinine, urea nitrogen, intact parathyroid hormone (iPTH) and fibroblast growth factor 23 (FGF-23) were measured. RESULTS: Twenty-four hour urinary phosphate excretion (UPE) was 283 ± 115 and 139 ± 57 mg/day (9.1 ± 3.5 and 4.5 ± 1.8 mmol/day) in groups A and B, respectively. Tubular reabsorption of phosphate (TRP) was 39.2 ± 13.3 and 31.7 ± 13.6% in groups A and B, respectively (P = 0.02). UPE significantly correlated with GFR (r = 0.85, P < 0.001) and PTH (r = 0.44, P < 0.001), but not with FGF-23, in the entire patient population. The correlation between UPE and intact PTH levels was absent in group B. Weekly UPE in group A was significantly greater (P < 0.001), while that in group B was similar to the amount of phosphate removed by a haemodialysis session. CONCLUSIONS: Urinary phosphate excretion by end-stage kidneys depends more on GFR than diminishing TRP. The action of PTH on the kidneys remains until GFR decreases to as low as 3 mL/min. Residual renal function plays a significant role in phosphate elimination, and it is possible that FGF-23 no longer acts effectively to excrete phosphate in the urine in these patients.
AIM: We investigated the handling of phosphate by end-stage kidneys and the contribution of residual renal function (RRF) to phosphate homeostasis in haemodialysis patients. METHODS: Blood and 24 h urinary specimens were obtained from 79 consecutive chronic haemodialysis patients with a urinary output greater than 100 mL/day. Thirty-five patients with a glomerular filtration rate (GFR) ≥ 3.0 mL/min were included as group A, and 44 patients with GFR < 3.0 mL/min as group B. Additionally, the whole dialysed fluids during a session of haemodialysis were collected from another nine patients. Concentrations of phosphate, creatinine, ureanitrogen, intact parathyroid hormone (iPTH) and fibroblast growth factor 23 (FGF-23) were measured. RESULTS: Twenty-four hour urinary phosphate excretion (UPE) was 283 ± 115 and 139 ± 57 mg/day (9.1 ± 3.5 and 4.5 ± 1.8 mmol/day) in groups A and B, respectively. Tubular reabsorption of phosphate (TRP) was 39.2 ± 13.3 and 31.7 ± 13.6% in groups A and B, respectively (P = 0.02). UPE significantly correlated with GFR (r = 0.85, P < 0.001) and PTH (r = 0.44, P < 0.001), but not with FGF-23, in the entire patient population. The correlation between UPE and intact PTH levels was absent in group B. Weekly UPE in group A was significantly greater (P < 0.001), while that in group B was similar to the amount of phosphate removed by a haemodialysis session. CONCLUSIONS: Urinary phosphate excretion by end-stage kidneys depends more on GFR than diminishing TRP. The action of PTH on the kidneys remains until GFR decreases to as low as 3 mL/min. Residual renal function plays a significant role in phosphate elimination, and it is possible that FGF-23 no longer acts effectively to excrete phosphate in the urine in these patients.
Authors: A-M Nechita; D Rădulescu; I Peride; A Niculae; O Bratu; D Ferechide; A Ciocâlteu; I A Checheriță; D Mischianu Journal: J Med Life Date: 2015 Jul-Sep
Authors: Nicolas Pallet; Sophie Chauvet; Jean-François Chassé; Marc Vincent; Paul Avillach; Charlene Levi; Vannary Meas-Yedid; Jean-Christophe Olivo-Marin; Diane Nga-Matsogo; Philippe Beaune; Eric Thervet; Alexandre Karras Journal: PLoS One Date: 2014-01-08 Impact factor: 3.240