Background: Red cell distribution width (RDW) measures variability in red blood cell size. It 
may also be useful as a biomarker of disease severity and clinical outcomes in critically ill 
patients. An increased RDW is an independent predictor of all-cause mortality in sepsis, 
congestive heart failure and has been shown to improve acute physiology scoring for risk 
prediction in critically ill adults. Patients and Methods: The medical records of 100 
critically ill patients were reviewed for a CBC, including RDW, measured within 24 hours of 
PICU admission. Results: There was significant increase in PIM-2, RDW and the frequency 
of anemia compared with others without mortality, while there was significant decrease in Hb 
and MCV levels, all are Risk factors for mortality. The optimal cutoff value of PIM-2 to 
predict mortality rate in the studied patients was >5.8% with a very high sensitivity 97.67% 
and specificity 98.25%, and the optimal cutoff value of RDW to predict mortality rate in the 
studied patients was >14.7% with a high sensitivity 81.4% and specificity 85.96%. 
Conclusion: RDW is a predictor of mortality in critically ill PICU patients. Taking into 
consideration the fact that RDW is routinely measured in complete blood count with no 
additional cost, this can serve as an “inexpensive prognostic marker" in critically ill patients.