The content of epithelial cells in the urine is one of the measurements that are part of the urinary sediment analysis. This information, in combination with other urinalysis data and the symptoms experienced by the patient, is useful in many cases to be able to make a correct diagnosis.
Epithelial cells are cells of epithelial tissue, the tissue that lines body surfaces, external and internal cavities, and ducts, such as the renal tubules, ureters, urinary bladder, and urethra. Old epithelial cells are shed from the epithelium and are replaced by new cells. can be found in urine under normal conditions. In men they are usually scarce and in women the normal amount is more variable depending on the phase of the menstrual cycle.
Either way, a high number of epithelial cells in the urine is a sign that something might be going on. The most frequent causes are infectious processes and inflammation of the urinary tract.
The epithelial cells in the urine are determined by microscopic examination of the urinary sediment. Urinary sediment is obtained by centrifuging urine. During centrifugation, the solid elements in suspension fall to the bottom forming a sediment that can be easily separated from the liquid fraction for study.
In addition to the presence of epithelial cells, the presence of bacteria and other microorganisms, blood cells (red blood cells, leukocytes), crystals (uric acid, cystine, oxalic acid), proteins, etc.
Types of epithelial cells in urine and their meaning
In general, a low number of epithelial cells is unimportant, but a high number is important to determine what type they are and their concentration. Three types of epithelial cells can be found in urine: squamous or flat, transitional and tubular cells of the renal epithelium.
Also called flat cells due to their shape, they are thin cells originating mainly from the epithelium of the vagina or the epithelium of the distal urethra and are common in low quantity in the urine. A high content of squamous epithelial cells is indicative of possible vaginitis or urethritis. This type of cell is also found in the epithelium of the genitals outside the body, so its presence in large numbers may be due to pollution or incorrect sample collection.
When a high number of squamous cells is found in the urine, a new sample is usually requested to compare the results, emphasizing collection standards and instructions that minimize the risk of contamination.
They arise from the epithelium that covers the proximal urethra and bladder. It is associated with inflammatory processes, usually related to infections. A high number of transitional cells is also seen in patients with nephrolithiasis.
renal tubular cells
They are the cells that cover the renal tubules (part of the nephron) and under normal conditions do not appear in the urine. Its presence is related to kidney damage such as acute tubular necrosis, some viral diseases (such as cytomegalovirus nephritis), pyelonephritis, transplant rejection and toxic reactions to certain substances. The so-called oval fat bodies are these same lipid-laden cells that appear in nephritic syndrome.
When tubular cells appear in the urine, it is common for more tests to be ordered and a kidney profile to be performed to find out what is happening in the kidney and be able to give a specific differential diagnosis.