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Introduction ⬇

In healthy persons, erythrocytes (RBCs) occasionally appear in the urine. However, persistent findings of even small numbers of RBCs should be thoroughly investigated because these cells come from the kidney and may signal serious kidney disease. They are usually diagnostic of glomerular disease. The presence of increased red cells in the urine is referred to as hematuria.

Normal Findings ⬆ ⬇

RBCs: 0–3/hpf (40× objective)

RBC casts: 0/lpf (20× objective)

Procedure ⬆ ⬇

  1. Observe the Procedure for Microscopic Urine Examination of this chapter.

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

Clinical Implications ⬆ ⬇

  1. RBC casts indicate hemorrhage in the nephron.

    1. RBC casts are found in three forms:

      1. Intact RBCs

      2. Degenerating cells within a protein matrix

      3. Homogeneous blood casts (“hemoglobin casts”)

    2. RBC casts indicate acute inflammatory or vascular disorders in the glomerulus and are found in:

      1. Glomerulonephritis (acute and chronic)

      2. Kidney infarction

      3. Lupus nephritis

      4. Goodpasture syndrome

      5. Severe pyelonephritis

      6. Heart failure

      7. Renal vein thrombosis

      8. Acute bacterial endocarditis

      9. Malignant hypertension

      10. Periarteritis nodosa

    3. RBCs should be present if RBC casts are in the sediment.

  2. RBCs

    1. The finding of more than 1 or 2 RBCs/hpf is abnormal and can indicate:

      1. Kidney or systemic disease (glomerulonephritis)

      2. Trauma to the kidney (vascular injury)

    2. Increased numbers of RBCs occur in:

      1. Pyelonephritis

      2. SLE

      3. Kidney stones

      4. Cystitis (acute or chronic)

      5. Prostatitis

      6. Tuberculosis (renal)

      7. Genitourinary tract malignancies

      8. Hemophilia, coagulation disorders

      9. Malaria

      10. Polyarteritis nodosa

      11. Malignant hypertension

      12. Acute febrile episodes

    3. Greater numbers of RBCs than WBCs indicate bleeding into the urinary tract, as may occur with:

      1. Trauma

      2. Tumors of rectum, colon, pelvis

      3. Aspirin overdose or other toxic drugs

      4. Anticoagulant therapy overdose

      5. Thrombocytopenia

Clinical Alert

  1. In health, RBCs are occasionally found in the urine. However, persistent findings of even small numbers of RBCs should be thoroughly investigated, the first step being to request a fresh urine specimen for repeat testing.

  2. Rule out the possible presence of menstrual blood, vaginal bleeding, or trauma to the perineal area in a female patient.

Interventions ⬆ ⬇

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.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. Monitor appropriately. Counsel the patient regarding abnormal findings.

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

Interfering Factors ⬆

  1. Increased numbers of RBCs may be found after a traumatic catheterization and after passage of urinary tract or kidney stones.

  2. Alkaline urine hemolyzes RBCs and dissolves casts (“ghosts”).

  3. Some drugs can cause increased numbers of RBCs in the urine (see Appendix E).

  4. RBC casts and RBCs may appear after very strenuous physical activity or participation in contact sports.

  5. Heavy smokers show small numbers of RBCs in the urine.

  6. Yeast or oil droplets may be mistaken for RBCs.