What Are Epithelial Cells?
Epithelial cells form protective layers over the skin, organs and internal passages of the body. In the urinary system, they line areas including the urethra, bladder, ureters and kidney tubules.
These cells naturally loosen and pass into the urine as the lining renews itself. For this reason, finding a few epithelial cells in a urine sample is common and may not indicate a health problem.
Epithelial cells are usually examined during the microscopic part of a urinalysis. The laboratory looks at both the number and type of cells present because different cells may come from different parts of the urinary system.
Why the Type of Cell Matters
An epithelial cell result is not interpreted only as “high” or “low.” The type of cell can provide more useful information about where it may have come from.
Squamous Epithelial Cells
Squamous epithelial cells usually come from the skin, genital area, or lower end of the urethra.
A few squamous cells may be present in a normal sample. Finding many of them often means that skin cells or genital secretions entered the container during collection. This may make the sample less reliable for assessing infection. Squamous cells are the epithelial cells most commonly seen in urine.
The laboratory or healthcare provider may request another clean-catch sample if contamination is suspected.
Transitional Epithelial Cells
Transitional epithelial cells, also called urothelial cells, line the bladder, ureters, and part of the urethra.
A small number may be found normally. Higher numbers may appear after irritation, inflammation, infection, catheter use, or another urinary procedure. The result must be reviewed with the person’s symptoms and the rest of the urinalysis.
Renal Tubular Epithelial Cells
Renal tubular epithelial cells come from the tiny tubes inside the kidneys.
These cells are less commonly found in urine than squamous cells. Increased renal tubular cells may require closer investigation because they can be associated with injury affecting the kidney tubules. However, they may be difficult to distinguish from transitional cells, so the result must be interpreted carefully and alongside other laboratory findings.
When May This Test Be Useful?
Epithelial cells may be reviewed as part of a urinalysis when a healthcare provider is investigating:
- a possible urinary tract infection
- blood or protein in the urine
- an unusual result from another urine test
- possible kidney tubular injury
- kidney or urinary tract inflammation
- the quality of a previously collected urine sample
- changes following catheterisation or another urinary procedure
A urinalysis may also be requested if you experience:
- pain or burning when urinating
- a frequent or urgent need to urinate
- cloudy or unusually strong-smelling urine
- visible blood in the urine
- lower abdominal or pelvic discomfort
- pain in the back or side
- fever or chills with urinary symptoms
These symptoms do not indicate that epithelial cells are necessarily abnormal. They are reasons to examine the urine for several findings, including blood cells, bacteria, protein, and epithelial cells.
How to Avoid Contaminating the Sample
A correctly collected sample is particularly important for this test because cells from the skin or genital area can enter the container and increase the number of squamous epithelial cells.
No fasting is normally required. Before collection:
- use the sterile container supplied by the laboratory
- inform the laboratory if you are menstruating
- avoid touching the inside of the container or lid
- follow the clean-catch instructions carefully
To provide a clean-catch midstream sample:
- Wash your hands and clean the genital area as instructed.
- Begin urinating into the toilet, then collect the middle portion of the stream in the sterile container.
- Close the container securely and return it according to the laboratory’s instructions.
A contaminated sample does not necessarily mean that there is a urinary condition. It may simply need to be collected again.
What Happens During Laboratory Examination?
The urine sample may be examined visually, chemically, and under a microscope.
During microscopic examination, the laboratory may identify:
- squamous epithelial cells
- transitional epithelial cells
- renal tubular epithelial cells
- white blood cells
- red blood cells
- bacteria or yeast
- crystals or urinary casts
The result becomes more useful when the cell type is considered with the other findings.
For example:
- Many squamous cells may suggest sample contamination
- Epithelial cells with white blood cells and bacteria may lead to further assessment for infection
- Renal tubular cells with casts or abnormal kidney results may require investigation for kidney injury
Epithelial cells alone cannot confirm any of these conditions.
How Are Results Reported?
Laboratories may report epithelial cells as:
- None
- Few
- Moderate
- Many
Some reports give the approximate number of cells seen per microscopic field. Others identify the cell type separately.
A small number of squamous or transitional cells may be considered normal. However, one general numerical range should not be applied to every epithelial cell type because laboratories use different methods and reporting systems.
Renal tubular epithelial cells are interpreted differently from common squamous cells and may be more clinically important when present in increased numbers.
The reference ranges vary depending on the laboratory and the methodology used. Individuals must consult their healthcare provider for correct interpretation of the results.
What Can an Unusual Result Mean?
An unusual epithelial cell result may have several explanations.
The Sample May Be Contaminated
A large number of squamous epithelial cells often suggests that cells from the skin or genital area entered the sample. This is a collection issue rather than proof of disease.
The urinalysis may need to be repeated using another clean-catch sample.
The Urinary Tract May Be Irritated
Increased transitional cells may occur when the lining of the bladder or urinary tract has been irritated. Possible reasons include inflammation, infection, catheter use, or a recent urinary procedure.
The Kidneys May Need Further Assessment
Renal tubular epithelial cells may be associated with changes affecting the kidney tubules, particularly when they appear with epithelial cell casts, protein, blood, or abnormal kidney function results. Free renal tubular cells and epithelial cell casts can be seen with acute tubular injury and certain other kidney conditions.
The finding does not identify the cause by itself.
What May Happen Next?
The next step depends on the epithelial cell type, the number reported, your symptoms, and the remaining urine findings.
A healthcare provider may recommend:
- repeating the urinalysis
- collecting another clean-catch urine sample
- a urine culture and sensitivity test
- blood tests for kidney function
- examination of the urine sediment
- urine protein testing
- ultrasound or other imaging
- assessment by a kidney or urinary specialist
Treatment is not given for epithelial cells themselves. Any treatment is based on the condition responsible for the abnormal urine findings.
Book An Appointment
Need an Epithelial Cells in Urine Test? Book an appointment with Genex Clinical Laboratories for urine analysis and microscopic examination.
