Guide to Transitional Epithelial Cells in Urine

WRITTEN BY

The Levels Team

Updated: 05/22/2025|12 min read

Summary

Transitional epithelial cells shed from the lining of your urinary tract that are excreted in urine and can suggest infection or irritation.

Why It Matters

Transitional epithelial cells are specialized cells that line much of your urinary tract, including parts of the kidneys, the ureters (tubes connecting kidneys to the bladder), the bladder, and portions of the urethra.

The primary function of transitional epithelium is protective---it forms a nearly impermeable barrier that prevents urine and its dissolved waste products from damaging surrounding tissues. It also plays a role in regulating the movement of substances between the urine and the bloodstream.

A small number of these cells naturally slough off and appear in urine as part of the normal renewal process. However, several factors can increase the shedding rate. 

These may include inflammation from infections like urinary tract infections (UTIs) and physical irritation from kidney stones, catheters, or certain medications. In some cases, higher numbers can suggest more serious conditions such as interstitial cystitis (chronic bladder inflammation) or even certain cancers affecting the urinary system.

Associated Symptoms 

Transitional epithelial cells in urine themselves are a laboratory finding rather than a medical condition. However, elevated levels may be associated with various urinary tract issues, each with its own symptoms.

Common symptoms that may indicate conditions associated with high levels of transitional epithelial cells (but can also occur with urinary tract infections) include:

• Frequent urination: Increased urge to urinate may be due to bladder irritation or inflammation
• Burning or pain during urination: Discomfort when passing urine can be caused by inflammation of the urinary tract lining
• Lower abdominal discomfort: Mild pain or pressure in the pelvic region, may be related to bladder inflammation
• Blood in urine: Visible (hematuria) or microscopic bleeding may be due to inflammation or damage to the urinary tract lining
• Cloudy or strong-smelling urine: Changes in urine appearance or odor can result from increased cellular content and possible infection
• Bladder pressure: Sensation of fullness or incomplete emptying even after urination

It's important to note that while elevated transitional epithelial cells can suggest inflammation or irritation of the urinary tract, the specific cause requires additional investigation. These cells may increase due to infections, stones, medication effects, or rarely, more serious conditions. The pattern and persistence of elevated cell counts, along with other urinalysis findings, help guide diagnosis and treatment decisions.

Lifestyle Factors That Can Impact It

Activities that may affect transitional epithelial cells in urine include:

• Hydration levels: Not drinking enough fluids concentrates urine, potentially irritating the urinary tract lining and increasing cell shedding.
• Holding urine for extended periods: Regularly delaying urination can stretch the bladder excessively and may irritate the epithelial lining.
• Personal hygiene: Poor hygiene practices can introduce bacteria to the urinary tract that increase transitional cell shedding. Proper wiping technique (front to back), regular cleaning, and wearing breathable underwear can help prevent bacterial growth.
• Diet choices: Highly acidic foods and beverages (like citrus, tomatoes, coffee, and alcohol) may irritate the bladder lining in sensitive people, potentially increasing cell shedding, though research is limited.
• Smoking: Tobacco contains harmful chemicals that are filtered through the kidneys and pass through the bladder, potentially damaging the epithelial lining and increasing cell turnover.

Other Factors That Can Impact It

Medical Conditions

• UTIs. Bacterial infections cause inflammation of the urinary tract lining, leading to increased cell shedding.
• Interstitial cystitis: This chronic condition involves inflammation of the bladder wall without infection, causing increased shedding of transitional cells.  
• Kidney stones: These mineral deposits physically irritate the epithelial lining as they move through the urinary tract.
• Sexually transmitted infections: Conditions like chlamydia and gonorrhea can cause urethritis (inflammation of the urethra), resulting in transitional epithelial cells in urine.
• Bladder or urinary tract cancers: Malignancies can disrupt the normal architecture and renewal of transitional epithelium, leading to abnormal cells and increased shedding.

Medications and Supplements

• Nonsteroidal anti-inflammatory drugs (NSAIDs) if used long term

Individual Factors

• Age: Older adults may have slightly higher rates of cell turnover.
• Sex: Women are more prone to UTIs, which can increase cell shedding.
• Pregnancy: Hormonal changes and pressure on the bladder can affect the urinary epithelium
• Recent urinary tract procedures: Catheterization, cystoscopy, or other interventions can temporarily increase cell shedding

Testing Accuracy and Stability

Transitional epithelial cell testing is generally reliable, but certain factors may affect results.

Factors That Can Affect the Accuracy of Your Test 

• Samples from the first urination of the morning may show higher cell counts
• While transitional epithelial cells originate from the urinary tract (kidneys, ureters, bladder, urethra), improper collection techniques can introduce squamous cells or debris, complicating the interpretation of transitional cell counts. A clean-catch midstream sample is also advised to minimize contamination issues.
• Vigorous exercise can temporarily increase shedding
• Urine samples should be analyzed within 1--2 hours or refrigerated to prevent cell breakdown or bacterial growth that can skew results.

How It Relates to Other Markers

Other tests can provide insights about health status when they're viewed alongside transitional epithelial cell results. These tests may include:

• Urine culture: Identifies specific bacteria if infection is suspected.
• Imaging studies (ultrasound, CT): Visualize the urinary tract structures to identify stones, tumors, or structural abnormalities.
• Cystoscopy: Direct visualization of the bladder lining using a thin, flexible scope allows physicians to examine the transitional epithelium for inflammation, lesions, or other abnormalities.
• Urine cytology: Examining cells in urine can help distinguish between normal transitional cells and potentially cancerous ones.

How results could relate to other marker values:

• Transitional cells + white blood cells + bacteria: This combination may suggest a urinary tract infection.
• Transitional cells + red blood cells without bacteria: May indicate non-infectious inflammation, stones, or possible tumors.
• Transitional cells + protein in urine: Could suggest kidney dysfunction affecting the filtration process.
• Transitional cells + crystals: Indicates potential stone formation, with crystals physically irritating the epithelial lining and causing increased cell shedding.

Follow-up Considerations

If high levels of transitional epithelial cells are detected in your urine, your provider may make some of the following recommendations. You should always speak to your doctor if you have medical questions or before making medical decisions.

When Re-Testing May Be Appropriate

• 2-4 weeks after any finding elevated levels
• As part of regular monitoring if you have recurrent urinary issues
• Following any changes in symptoms related to urination

Additional Testing Your Doctor May Consider

• Kidney function tests if persistent abnormalities are found
• Specialized urine cytology if cells appear atypical
• Imaging studies if structural issues are suspected
• Bladder pressure studies if interstitial cystitis is being considered

When Additional Care May Be Warranted

• If you have visible blood in your urine
• If you experience persistent pain during urination despite treatment
• If you develop fever, chills, or back pain along with urinary symptoms
• If transitional cells are elevated with atypical cells or persistent blood in urine, your doctor may recommend urgent urine cytology or cystoscopy to rule out bladder cancer.
• If elevated transitional epithelial cells persist after treatment
• If you have a family history of urinary tract cancers and abnormal findings

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