MO394TWO POINT ESTIMATE OF KINETIC GFR IN ACUTE KIDNEY DISEASE

Abstract

Abstract Background and Aims When anuria suddenly occurs, the rise in creatinine and consequently the decrease in the estimated glomerular filtration rate (eGFR) will always be delayed. Thus, the drug dose could be selected too high in the progressive phase whereas it could be adjusted too low in the restitution phase of acute kidney disease (AKD). Sheldon Chen proposed a solution for changing kidney function with the kinetic GFR (KeGFR). A simplified but also more general solution (kinetGFR) might even facilitate the automatic implementation into lab systems. Method Deterioration of kidney function is diagnosed when the creatinine increases within a definite time interval (Δ t) and the estimated eGFR declines (Δ eGFR). The new 2-point estimate of the kinetGFR can be derived when the prospective eGFRt+24 predicted for the next day (t+24) will be set equal to the present true GFR at critical day (t2). kinetGFR=eGFR2−eGFR1−eGFR2t2−t1⋅t+24 h The 24 h delay follows from anuria, the most extreme and most relevant case (GFR = 0). A zero GFR will be associated with a linear rise in creatinine according to the constant production rate by roughly 100 µmol/l every day. This rise leads to the corresponding bisection of the estimated eGFR nearly every day (100 => 50 => 25 => 13 => … ml/min). The curvilinear eGFR decline will never become zero even after > 2 weeks. The new kinetGFR can identify a complete anuria already after one day (24 h). kinetGFR=50−100−5024−0⋅24=0.0 ml/min This is already at the critical day (t2). Results The retrospective look at the anonymized data from 20 patients with AKD allowed for comparing the former KeGFR with the new two-point kinetGFR estimate. For worsening kidney function, the average eGFR2 was 18 ml/min (+ 12) and the KeGFR estimate was not different with 19 ml/min (+ 17). The new 2-point kinetGFR, however, was 13 ml/min (+ 11) and 28 % less than eGFR2 at the critical day (t2). For improving kidney function, the eGFR2 was 15 ml/min (+ 4) and the KeGFR was already much higher at 27 ml/min (+ 3). The new 2-point estimate of the kinetGFR was in between at 21 ml/min (+ 7). Conclusion In AKD, the difference between eGFR and presumably true GFR was the higher the more rapidly kidney function declined. The new kinetGFR estimate appears clinically more plausible than the former KeGFR estimates.