Introduction and Aims
25-hydroxy vitamin D (25(OH)D) levels may show some seasonal variance in dialysis patients due to differences in alimentation and sun exposure, but the relation between 25(OH)D levels and residual renal function in adult peritoneal dialysis (PD) patients is not known.
Weekly creatinine clearance (Crea-Cl), urea clearance (Urea-Cl), fractional excretion of urea (FE-Urea) and renal KT/V were analysed in 32 PD patients together with serum 25(OH)D.
All patients had residual diuresis of at least 100 ml per day and were under high dose furosemide therapy of at least 250 mg per day.
The patients did not receive oral vitamin D supplementation. Vitamin D receptor agonists (calcitriol or paricalcitol) were given to control calcium-phosphorous-parathormone.
Adult PD patients (mean age 63±16 years) presented mean diuresis of 1108±683 ml per day, Crea-Cl of 49±34 L/week, Urea-Cl of 25±15 L/week, FE-Urea of 0.54±0.16 and renal Kt/V 0.68±0.46.
Mean values of 25(OH)D were at 13.9±7.7 ng/l. Two patients presented 25(OH)D levels above 30 ng/ml, five patients 25(OH)D insufficiency (20-30 ng/ml) and the remaining 25 patients deficiency (<20 ng/ml).
Serum 25(OH)D levels correlated to renal creatinine excretion (r=0.35, p=0.049), renal urea excretion (r=0.42, p=0.02), FE-Urea (r=0.40, p=0.02) and Urea-Cl (r=0.41, p=0.02), but not to diuresis, Cl-Crea or Kt/V.
Serum 25(OH)D was in the majority of cases in the range of deficiency.
Several parameters of residual renal function were associated to 25(OH)D, especially parameters regarding
urea elimination (daily urinary excretion of urea, FE-Urea and Urea-CL).
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