Prognostic value of tubular proteinuria and enzymuria in nonoliguric acute tubular necrosis.
BACKGROUND
Acute tubular necrosis (ATN) has high mortality, especially in patients who require renal replacement therapy (RRT). We prospectively studied the diagnostic accuracy of the urinary excretion of low-molecular-weight proteins and enzymes as predictors of a need for RRT in ATN.


METHODS
In 73 consecutive patients with initially nonoliguric ATN, we measured urinary excretion of alpha(1)- and beta(2)-microglobulin, cystatin C, retinol-binding protein, alpha-glutathione S-transferase, gamma-glutamyltransferase, lactate dehydrogenase, and N-acetyl-beta-D-glucosaminidase early in the course of ATN.


RESULTS
Twenty-six patients (36%) required RRT a median of 4 (interquartile range, 2-6) days after detection of proteinuria and enzymuria. Patients who required RRT had higher urinary cystatin C and alpha(1)-microglobulin [median (interquartile range), 1.7 (1.2-4.1) and 34.5 (26.6-45.1) g/mol of creatinine] than patients who did not require RRT [0.1 (0.02-0.5) and 8.0 (5.0-17.5) g/mol of creatinine]. Urinary excretion of cystatin C and alpha(1)-microglobulin had the highest diagnostic accuracies in identifying patients requiring RRT as indicated by the largest areas under the ROC curves: 0.92 (95% confidence interval, 0.86-0.96) and 0.86 (0.78-0.92), respectively. Sensitivity and specificity were 92% (95% confidence interval, 83-96%) and 83% (73-90%), respectively, for urinary cystatin C >1 g/mol of creatinine, and 88% (78-93%) and 81% (70-88%) for urinary alpha(1)-microglobulin >20 g/mol of creatinine.


CONCLUSIONS
In nonoliguric ATN, increased urinary excretion of cystatin C and alpha(1)-microglobulin may predict an unfavorable outcome, as reflected by the requirement for RRT.
Herget-Rosenthal
Stefan
S
Department of Nephrology, University Hospital, Essen, Germany. stefan.herget-rosenthal@uni-essen.de
Poppen
Dennis
D
Hüsing
Johannes
J
Marggraf
Günter
G
Pietruck
Frank
F
Jakob
Heinz-Günther
HG
Philipp
Thomas
T
Kribben
Andreas
A
D000368:Aged; D015415:Biomarkers / Q000652:urine; D004798:Enzymes / Q000652:urine*; D005260:Female; D006801:Humans; D007683:Kidney Tubular Necrosis, Acute / Q000175:diagnosis* / Q000628:therapy / Q000652:urine*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011507:Proteinuria / Q000175:diagnosis* / Q000628:therapy / Q000652:urine*; D017582:Renal Replacement Therapy; D012189:Retrospective Studies
D015415:Biomarkers; D004798:Enzymes