LONGITUDINAL EVALUATION OF A RENAL KT V-UREA OF 2.0 AS A THRESHOLD FOR INITIATION OF DIALYSIS/

We (Perit Dial int 17:426 and 497, 1997) and the Dialysis Outcomes Qua lity Initiative guidelines (Am J Kidney Dis 30:S69, 1997) have reporte d evidence that protein intake often is < 0.8 g/kg standard weight whe n renal weekly urea clearance (L) normalized to total body water (V, L ) is less than 2.0, and that initiation of dialysis should be consider ed if nutritional status is decreasing. We have prospectively followed renal urea (C-urea) and creatinine clearances (C-cr) in 20 patients w ith chronic renal failure. Nine patients received dietary counseling, but we have previously shown this has minimal effects on protein intak es (Perit Dial Int 17:497, 1997). In 16 patients (group 1), glomerular filtration rate (GFR) estimated as (C-urea + C-cr)/2 decreased from 1 4.6 +/- 1.5 (mean +/- SEM) to 9.8 +/- 0.9 (ml/min/1.73 m(2) BSA) over a mean interval of 10.3 + w1.6 months; in the other 4 patients (group 2), mean GFR did not decrease and was initially 17.6 +/- 3.8 and 21.7 +/- 2.2 after 8.5 +/- 2.3 months. In group 1, Kt/ V went from 2.5 +/- 0.3 to 1.7 +/- 0.2; in group 2, Kt/V went from 3.1 +/- 1.0 to 3.7 + 0. 6. In group 1, protein intake as assessed from the normalized equivale nt of protein nitrogen appearance calculated from urea nitrogen and pr otein losses in urine (nPNA; g/kg standard weight) went from 1.0 +/- 0 .1 to 0.8 +/- 0.1. In group 2, mean nPNAs were 1.1 +/- 0.3 and 1.1 +/- 0.1. In all measurements with Kt/V less than 2.0 (n = 18), 10 (56%) w ere with nPNA less than 0.8. In all measurements of Kt/V greater than or equal to 2.0 (n = 22), only 3 (13.6%) were with an nPNA of less tha n 0.8. These percentage values were different (p < 0.0001) by chi-squa red analysis. Changes in nPNA correlated directly (but insignificantly , probably because of a small n) with C-cr, GFR, and Kt/V. These prosp ective results provide additional evidence that protein intakes decrea se to dangerously low levels (without intense dietary monitoring) in m ost patients when renal weekly Kt/V decreases to below 2.0, which is s imilar to findings in patients on continous ambulatory peritoneal dial ysis.