RBC/UA

Blood in Urine

Análisis de orina

Última revisión: 7 de abril de 2026. Enfoque de fuentes: contexto estándar de interpretación de laboratorio, material médico de referencia y orientación clínica o de salud pública cuando corresponde.

¿Qué es Blood in Urine?

Blood in urine, medically known as hematuria, is the presence of red blood cells in the urine. It can be visible to the naked eye (gross hematuria), causing the urine to appear pink, red, or cola-colored, or detectable only under a microscope or through chemical testing (microscopic hematuria). Hematuria is one of the most common abnormal findings on urinalysis and can originate from anywhere along the urinary tract—the kidneys, ureters, bladder, prostate, or urethra.

The detection of blood in urine involves either microscopic examination of urine sediment, where red blood cells are counted per high-power field, or a dipstick test that detects the peroxidase activity of hemoglobin. While dipstick tests are highly sensitive, they can produce false-positive results from myoglobin, certain medications, or concentrated urine. Hematuria ranges from benign causes like vigorous exercise to serious conditions including kidney disease, urinary tract cancers, and bleeding disorders, making proper evaluation essential.

Por qué importa

Blood in urine should never be ignored, as it can be an early sign of serious conditions including bladder cancer, kidney cancer, kidney disease, and kidney stones. Even microscopic hematuria detected incidentally requires systematic evaluation, as studies show that approximately 3–5% of patients with asymptomatic microscopic hematuria will be found to have a urologic malignancy. Early detection of these conditions significantly improves treatment outcomes. Hematuria is also an important indicator of glomerular diseases that, if left untreated, can progress to chronic kidney failure.

Rangos de referencia normales

GrupoRangoUnidad
Microscopic exam0–2RBC/HPF
DipstickNegative

Los rangos de referencia pueden variar entre laboratorios. Compara siempre tus resultados con los rangos proporcionados por tu laboratorio.

Qué significan los niveles altos de RBC/UA

Causas comunes

  • Urinary tract infection
  • Kidney stones
  • Bladder or kidney cancer
  • Glomerulonephritis
  • Enlarged prostate (BPH)
  • Vigorous exercise (runner's hematuria)
  • Blood thinning medications (anticoagulants)
  • Trauma to the kidneys or urinary tract

Posibles síntomas

  • Pink, red, or cola-colored urine
  • Painful urination (if infection or stones)
  • Flank or back pain (kidney stones or infection)
  • Frequent urination or urgency
  • Blood clots in urine
  • Often asymptomatic with microscopic hematuria

Qué hacer: Any confirmed hematuria requires evaluation. Your doctor may order a urine culture, kidney function tests, imaging studies (CT urogram or ultrasound), and possibly a cystoscopy to directly visualize the bladder lining. If you are on blood thinners, hematuria still warrants investigation—anticoagulants may unmask an underlying condition. Urgent evaluation is needed if there is significant visible blood, blood clots, or associated pain.

Qué significan los niveles bajos de RBC/UA

Causas comunes

  • Normal finding—healthy urine should contain no significant red blood cells
  • Resolved infection or kidney stone after treatment

Posibles síntomas

  • No symptoms—absence of blood in urine is normal

Qué hacer: A negative result for blood in urine is normal. If you had a previous episode of hematuria that has resolved, your doctor may recommend follow-up testing to ensure the underlying cause has been addressed.

¿Cuándo se recomienda la prueba de RBC/UA?

  • When urine appears pink, red, or brown
  • As part of a routine urinalysis
  • When experiencing flank pain or painful urination
  • In patients on anticoagulant therapy
  • For screening in individuals over 50 with risk factors for bladder cancer
  • To evaluate unexplained anemia

Preguntas frecuentes

Yes, intense exercise—particularly long-distance running, cycling, and contact sports—can cause transient hematuria, sometimes called "runner's hematuria" or "march hemoglobinuria." This occurs due to repeated bladder trauma from impact, increased glomerular permeability during exertion, or breakdown of red blood cells in the feet during running. Exercise-induced hematuria typically resolves within 24–72 hours of rest. However, if blood persists after rest or recurs frequently, it should be evaluated to rule out other causes.
Several substances can cause red or pink discoloration of urine that mimics hematuria. Beets, blackberries, and rhubarb contain pigments that can turn urine pink or red. Medications including rifampin, phenazopyridine (Pyridium), and certain laxatives containing senna can also discolor urine. These causes are called "pseudohematuria" because no actual blood is present. A dipstick test or microscopic examination will be negative for red blood cells in these cases, distinguishing them from true hematuria.
Not always, but it should always be evaluated. Studies show that many cases of microscopic hematuria have benign explanations such as a mild urinary tract infection, menstrual contamination, vigorous exercise, or benign prostatic enlargement. However, because a small but significant percentage of patients with microscopic hematuria have an underlying malignancy or kidney disease, current guidelines recommend that persistent microscopic hematuria (found on two or more tests) be evaluated with imaging and possibly cystoscopy, particularly in adults over 35.

Biomarcadores relacionados

WBC/UALeukocytes in UrineuProtProtein in UrineCrCreatininaRBCGlóbulos rojos

Referencias y enfoque de revisión

Las páginas del glosario de biomarcadores son explicaciones educativas y deben interpretarse junto con los rangos de referencia y comentarios proporcionados por tu laboratorio y tu profesional de salud. Para conocer nuestros estándares editoriales y proceso de revisión, consulta nuestra Política editorial y nuestro Proceso de revisión de contenido.

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Aviso médico: Esta información es solo educativa y no sustituye el consejo, diagnóstico ni tratamiento médico profesional. Los rangos de referencia pueden variar entre laboratorios. Consulta siempre a tu profesional sanitario para interpretar tus resultados concretos.

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