Leukocytes (WBCs) may originate from anywhere in the genitourinary tract. They are also capable of ameboid migration through the tissues to sites of infection or inflammation. An increase in urinary WBCs is called pyuria and indicates the presence of an infection or inflammation in the genitourinary system. However, WBC casts always come from the kidney tubules.

WBCs: 0–4/hpf; Women may have slightly more WBCs.

WBC casts: 0/lpf

1. Observe the Procedure for Microscopic Urine Examination on pages xxx through xxx of this chapter.

2. Urinary sediment is microscopically examined under high power for cells and under low power for casts.

1. White blood cells

   1. Large numbers of WBCs (>30/hpf) usually indicate acute bacterial infection within the urinary tract.

   2. Increased WBCs (pyuria) are seen in:

      1. All kidney disease

      2. Urinary tract disease (e.g., cystitis, prostatitis, urethritis)

      3. Appendicitis, pancreatitis

      4. Strenuous exercise

      5. Chronic pyelonephritis

      6. Bladder tumors

      7. Tuberculosis

      8. SLE

      9. Interstitial nephritis

      10. Glomerulonephritis

   3. With bladder infections, WBCs tend to be associated with bacteria, epithelial cells, and relatively few RBCs.

   4. Large numbers of lymphocytes and plasma cells in the presence of a kidney transplant may indicate early tissue rejection (acute kidney allograft rejection).

   5. Eosinophils are associated with tubulointerstitial disease and hypersensitivity to penicillin.

   6. WBC clumps suggest kidney origin of WBCs and should be reported when present.

2. WBC casts

   1. WBC casts indicate renal parenchymal infection and may occur in:

      1. Pyelonephritis

      2. Acute glomerulonephritis

      3. Interstitial nephritis

      4. Lupus nephritis

   2. It can be very difficult to differentiate between WBC casts and epithelial cell casts.

Pretest Patient Care

1. Explain purpose of test, procedure for random urine sample collection, and interfering factors.

2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Vaginal discharge can contaminate a specimen with WBCs. A clean-catch urine specimen or a catheterized urine specimen should be obtained to rule out contamination as the cause for WBCs in the urine.