The significance of tubular and glomerular proteinuria in critically ill patients with severe acute kidney injury

Objective: Critically ill patients with acute kidney injury (AKI) frequently need acute renal replacement therapy (aRRT). We evaluated an inexpensive, rapid quantitative and qualitative analysis of proteinuria on the course of AKI patients requiring aRRT in intensive care.

Method: This was a prospective, observational study of critically ill patients with severe established AKI or Acute on Chronic Kidney Injury (AoCKI) requiring aRRT. Urine samples were analyzed using Sodium-Dodecyl-Sulphate-Polyacryamide Gel Electrophoresis (SDS-PAGE).

Results: A total of 30 critically ill patients were studied. Those who died have higher APACHE II (29 ± 6 vs. 20 ± 5, p<0.001), multi-organ failure (0.7 ± 0.5 vs. 0.2 ± 0.4, p < 0.02) and Tubular/Glomerular ratio (114 ± 60 vs. 75± 37, p < 0.05).The renal non-recoverers have higher baseline creatinine (415 ± 328 vs. 125± 19 umol/l, p < 0.01), urinary Dipstick value (1.8±0.8 vs. 0.5±0, p <0.05) and Glomerular score (3.0 ± 1.8 vs. 0.6 ± 0.2, p < 0.02).Heavy tubular proteinuria also predicts a longer duration of interim dialysis support and mortality whereas glomerular proteinuria correlates with development of chronicity and End Stage Renal Disease (ESRD).

Conclusions: The dominant presence of tubular proteinuria is associated with poor survival in patients who have high APACHE II score and multi-organ failure. It also correlates with a longer duration of dialysis support in survivals. Renal Non-recoverers had heavy dominant presence of glomerular proteinuria. SDS-PAGE proteinuria analysis offers a reliable and inexpensive method to prognosticate proteinuria in this group of critically ill patients.