Examination of the peripheral blood film and of the urinary sediment are powerful diagnostic tools, much as is physical examination of the heart. The power of these tests is unappreciated by many physicians….
Recently the performance of urine microscopy in the diagnosis of ATN was systematically evaluated:
Results: The urinary sediment scoring system was highly predictive of the final diagnosis of ATN. In patients with a high pretest probability of ATN (initial diagnosis of ATN), any casts or RTEC (score 2) resulted in very high positive predictive value and low negative predictive value for a final diagnosis of ATN. In patients with a low pretest probability of ATN (initial diagnosis of prerenal AKI), lack of casts or RTEC on urinary
sediment examination had a sensitivity of 0.73 and specificity of 0.75 for a final diagnosis of prerenal AKI. The negative predictive value of lack of casts or RTEC in patients with low pretest probability of disease was 91%.
Conclusions: Urine sediment examination is a valuable diagnostic tool for confirming the diagnosis of ATN. A score of 2 on an ATN urinary sediment scoring system is an extremely strong predictor of ATN.