The average leukocyte count in appendicitis is 15,000/L, and 90% of patients have counts over 10,000/L. In three-fourths of patients, the differential white count shows more than 75% neutrophils. It must be emphasized, however, that one patient in ten with acute appendicitis has a leukocyte count indistinguishable from normal, and many have normal differential cell counts. Appendicitis in patients infected with HIV produces the same syndrome as in other people, but the white blood cell count is usually normal.
The urine is usually normal, but a few leukocytes and erythrocytes and occasionally even gross hematuria may be noted, particularly in retrocecal or pelvic appendicitis.