What is a microscopic urinalysis?

Urinalysis is a diagnostic tool that is commonly used in diagnosing urinary tract diseases and other disorders that can affect the kidneys. This is an effective way to test kidney health because the kidneys filter urine before it is excreted. Examining urine content can help provide clues about kidney health. In microscopic urinalysis, a close examination of a urine sample is performed under a microscope.

Urinalysis generally involves two stages: gross urinalysis and microscopic urinalysis. In gross analysis, a urine sample is examined simply by looking at its color, opacity, and other factors such as sugar and protein content. Healthy urine is clear, pale yellow or pale amber in color, and contains no particles. If gross analysis shows that the urine is cloudy, abnormally colored, or contains a high proportion of protein, this can help determine a diagnosis.

In microscopic urinalysis, a small sample of urine is centrifuged to remove fluid. The sediment is examined under a microscope. In a typical microscopic urinalysis, a sample is examined for the presence of red and white blood cells, renal epithelial cells, bacteria, casts, and crystals.

Small numbers of renal epithelial cells are usually present in a normal urine sample. These cells are naturally expelled by the kidney tubules as new cells grow. If there are a large number of these cells in a sample, this is usually an indication of some type of disease in the kidney or upper urinary tract.

The presence of red blood cells in a urine sample can be an indication of various disease processes. These include kidney or urinary tract damage, kidney or urinary stones, and urinary tract infection. A small amount of blood is normal in a sample from a woman who is menstruating or in a sample from someone who recently had a bladder catheter inserted. In general, red blood cells are not present in the urine, and the presence of these cells is almost always an indicator of an abnormal sample.

White blood cells can be present in both normal and abnormal urine samples, but the presence of these cells probably indicates an infection. In general, white blood cells in a urine sample are an indication of a urinary tract infection or kidney infection. In some cases, a urine sample can become contaminated with white blood cells from the external genital area. When this happens, it is often an indication of an external genital infection.

It is common to find bacteria in a normal urine sample, particularly if the sample was administered by a woman or girl. This is because a sample is likely to contain cells and bacteria from the external genital area. Therefore, bacterial microscopic urinalysis involves examining the types of bacteria present in a sample, rather than simply the presence of bacteria. In most cases, this requires a urine sample to be cultured to determine which bacteria are present in numbers large enough to cause infection.

Molds and crystals are groups of substances, usually cells or molecules, that pass into the urine. Casts are clusters of red or white blood cells that have stuck together. In general, the presence of red blood cell casts indicates kidney infection or kidney disease of some kind. If there are white blood cell casts, this is a strong indicator of acute kidney infection or inflammation. When crystals are found in a microscopic urinalysis, this could indicate liver disease, but small amounts of casts are often seen in samples from healthy people.

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