Which statement about PMN percentage in peritonitis evaluation is true?

• A. PMN >50% is strong evidence of peritonitis even if TNC < 100
• B. PMN >50% indicates no infection
• C. PMN percentage is irrelevant
• D. PMN count >100 indicates peritonitis

Answer: (A)

Neutrophil (PMN) predominance in the dialysate is the key signal clinicians use to identify peritonitis in PD patients. When the effluent shows more than half of the cells as PMNs, it indicates a neutrophil-dominated inflammatory response consistent with infection. This can be strong evidence of peritonitis even if the total nucleated cell count is below 100/µL, because the high proportion reflects the active infectious process rather than just the absolute cell number. In practice, this PMN percentage is a crucial clue that guides urgent evaluation and treatment, alongside clinical symptoms and culture results. The other statements misinterpret what the PMN differential tells you: a PMN >50% does not indicate no infection; the PMN percentage is informative and not irrelevant; and simply having a PMN count >100 without considering the percentage does not capture the diagnostic nuance.