Occult Blood in Urine: Causes, Symptoms, and Treatments

Jun 27, 2024 | 6 min read

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Occult blood in urine can signal conditions like infections, stones, or cancer. Identifying and treating the cause early is vital for maintaining good health.

occult blood in urine

What is Occult Blood in Urine?

The medical term for the presence of blood in the urine is hematuria. Hematuria can be classified into two categories: 

  • Gross Hematuria: This type of hematuria is when blood is visible in the urine, making it appear red or pink. It is easily noticeable and typically leads to immediate medical attention.
  • Microscopic Hematuria (Occult Blood): This occurs when the blood is present in the urine in such small amounts that it cannot be seen without a microscope. This hidden blood requires specialized tests for detection.

Occult blood in urine refers to the presence of blood that is not visible to the naked eye but can be detected through chemical tests or microscopic examination. This condition is often identified during routine urinalysis.

Levels of Occult Blood:

  • Significant Microscopic Hematuria: 3 or more red blood cells (RBC)/hpf (≥ 3 RBC/hpf). Significant levels often warrant further investigation to determine the underlying cause.
  • Insignificant Microscopic Hematuria: 2 or fewer RBC/hpf (0-2 RBC/hpf). Insignificant levels may not require further testing unless accompanied by other symptoms or risk factors.

Common Causes of Occult Blood in Urine

Occult blood in urine can be caused by various conditions. Identifying the underlying cause is crucial for proper treatment and management.

Urinary Tract Infections (UTIs)

  • UTIs are a common cause of blood in the urine. Bacteria entering the urinary tract can cause inflammation and infection, leading to microscopic bleeding.
  • Symptoms may include a frequent urge to urinate, pain during urination, and lower abdominal discomfort.
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Kidney Stones

  • Kidney stones are hard mineral deposits that form in the kidneys. When these stones pass through the urinary tract, they can cause bleeding.
  • Symptoms often include severe pain in the back or side, nausea, and blood in the urine.

Bladder Stones

  • Similar to kidney stones, bladder stones are hard masses that form in the bladder. They can cause irritation and bleeding as they move through the urinary system.
  • Common symptoms include lower abdominal pain, frequent urination, and cloudy or bloody urine.

Kidney Infections

  • Also known as pyelonephritis, kidney infections occur when bacteria travel from the bladder to the kidneys, causing inflammation and microscopic bleeding.
  • Symptoms include fever, chills, back pain, and nausea.

Enlarged Prostate (BPH)

  • Benign prostatic hyperplasia (BPH) is a common condition in older men where the prostate gland enlarges and can compress the urethra, leading to hematuria.
  • Symptoms include difficulty urinating, a weak urine stream, and frequent urination.

Trauma and Injury

  • Injuries to the kidneys or bladder can occur from various causes, such as car accidents, falls, or sports activities. These injuries can result in bruising or tearing of the organs, leading to blood appearing in the urine.
  • Physical activities that involve heavy lifting or contact sports can also cause minor injuries to the urinary tract. Even though these injuries might not be severe, they can still cause bleeding that is detected as occult blood in urine.

Certain Medications

  • Some medications can cause bleeding in the urinary tract, leading to occult blood in the urine. Blood thinners, for example, can prevent blood from clotting properly, which might cause bleeding in various parts of the body, including the urinary system.
  • Certain antibiotics and other medications can irritate the bladder lining or kidneys, leading to inflammation and microscopic bleeding.

Cancer: Kidney, Bladder, Prostate

  • Blood in the urine can be a symptom of cancers affecting the kidneys, bladder, or prostate. Early detection and treatment are crucial.
  • Symptoms vary but may include unexplained weight loss, persistent pain, and changes in urination patterns.

Other Causes

  • Sickle Cell Anemia: A genetic disorder that affects the shape of red blood cells, leading to various complications, including hematuria.
  • Hemophilia: A genetic condition that impairs blood clotting, which can lead to internal bleeding, including in the urinary tract.
  • Vigorous Exercise: Intense physical activity can sometimes cause temporary blood in the urine, often resolving without treatment.

Diagnosis of Occult Blood in Urine

Diagnosing occult blood in urine involves a series of tests to identify the presence of red blood cells and determine the underlying cause. Early and accurate diagnosis is crucial for effective treatment.

Laboratory Tests


  • Detailed Process: During a urinalysis, a urine sample is collected and analyzed in a lab. The test involves examining the physical, chemical, and microscopic aspects of the urine.
  • What Results Mean: The presence of red blood cells, white blood cells, bacteria, and other substances is evaluated. A significant number of red blood cells indicates microscopic hematuria.
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Urine Cytology

This test involves examining urine samples under a microscope to detect abnormal cells. It is particularly useful for identifying cancerous or precancerous conditions in the urinary tract.

Test Interpretation

Interpreting lab results accurately is essential. A healthcare provider can explain what the results mean and recommend further testing or treatment if necessary.

Also, use an online Lab Test Interpretation tool to upload your urine results and receive a quick and detailed explanation. However, this should not replace professional medical advice.

At-Home Testing

At-home dipstick tests are a convenient way to detect occult blood in urine. These tests involve dipping a test strip into a urine sample. The strip changes color if blood is present, providing a qualitative or semi-quantitative result.

While these tests can indicate the presence of blood, they do not measure the exact amount and should be followed up with professional medical evaluation.

Imaging Tests

  • CT Scans: A CT scan provides detailed cross-sectional images of the urinary tract, helping to identify stones, tumors, or other abnormalities.
  • MRIs: MRI scans use magnetic fields to produce detailed images of the urinary system, useful for detecting structural issues and soft tissue abnormalities.
  • Ultrasounds: Ultrasound imaging uses sound waves to create images of the kidneys, bladder, and other urinary organs, helping to identify blockages, stones, or tumors.


  • Procedure: Cystoscopy involves inserting a thin, flexible tube with a camera (cystoscope) into the bladder through the urethra. This allows the doctor to directly visualize the bladder and urethra to identify abnormalities.
  • Purpose: The procedure helps diagnose conditions such as bladder tumors, stones, and structural abnormalities. If necessary, a biopsy can be taken during the procedure for further analysis.

Treatment Options for Occult Blood in Urine

Treating occult blood in urine involves addressing the underlying cause of the condition. Depending on the diagnosis, various treatment options are available to manage and eliminate the source of bleeding:

  • Antibiotics: If a urinary tract infection (UTI) is causing hematuria, antibiotics are prescribed to clear the infection.
  • Medication Adjustments: If medications, like blood thinners, are contributing, your doctor might adjust the dosage or switch medications.
  • Treatment for Kidney Stones: Small stones may pass on their own with increased fluid intake, while larger stones might need medical procedures such as lithotripsy or surgery.
  • Bladder or Kidney Infections: These are treated with appropriate antibiotics.
  • Cancer Treatment: If cancer is detected in the urinary tract, treatment options include surgery, chemotherapy, or radiation therapy.
  • Prostate Treatment: For hematuria due to prostate issues, treatments might include medication, minimally invasive procedures, or surgery.
  • Management of Glomerulonephritis: This kidney condition might require medications such as corticosteroids or other immune-suppressing drugs.

It's important to follow up with your healthcare provider to determine the specific cause of hematuria and the most appropriate treatment plan.

False Positives and Other Considerations

A study in the Experimental and Therapeutic Medicine Journal found that false positive results for occult blood in urine are quite frequent (22%) when using dipstick tests.

Understanding the factors that can lead to false positives in urine tests is important for accurate diagnosis and treatment.


Dehydration can concentrate the urine, leading to a higher likelihood of detecting blood. Ensuring adequate hydration before a urine test can help avoid false positives.

Diet and Exercise:

Certain foods, such as beets and berries, can discolor urine, mimicking the appearance of blood. Intense physical activity, such as long-distance running, can also cause temporary blood in the urine, known as runner’s hematuria. It is advisable to avoid such foods and strenuous exercise before a urine test to prevent misinterpretation of results.


Some medications, including blood thinners and certain antibiotics, can cause blood to appear in the urine. It is important to inform your healthcare provider of any medications you are taking, as they may affect test results.

When to See a Doctor

  • Severe pain in the back or lower abdomen
  • Blood visible in the urine
  • Persistent and frequent urge to urinate
  • Painful urination
  • Unexplained weight loss
  • Persistent fatigue or weakness

Regular check-ups can help detect occult blood in urine early, even before symptoms appear. Early detection can lead to prompt treatment and better health outcomes.

Frequently Asked Questions

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Occult blood in urine can be caused by various conditions, including infections, stones, and cancers. It is important to diagnose the underlying cause accurately through appropriate testing. Early diagnosis and treatment are crucial to prevent complications and maintain good health. If you notice symptoms or have concerns, consult with a healthcare professional for proper evaluation and care.

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