Your Guide to Understanding the Different Types of Urinary Casts

There are many different types of urinary casts that can indicate important health information.

A urinary cast is a small tube-like structure sometimes found when urine is examined under a microscope. These structures can indicate problems with your kidneys, along with certain conditions and infections.

Sometimes, otherwise healthy people can develop temporary urinary casts as a result of dehydration.

Testing for urinary casts is done as part of a simple and noninvasive urine collection and urinalysis. There’s no risk or pain involved in this testing.

Several types of casts can be found in urine. The type of cast varies depending on the substances that make up that cast.

For instance, casts can be made of proteins, red blood cells, white blood cells, bacterial, and epithelial cells, fatty substances, and more. The makeup of casts is an indicator of their underlying cause and can help doctors use the casts to confirm a diagnosis.

The types of urinary casts include:

• Hyaline casts: Hyaline casts are made of a protein called uromodulin. They can be the result of every day and easily fixable conditions like dehydration or strenuous exercise, or chronic conditions like renal disease.
• Red blood cell (RBC) cast: RBC casts are composed of red blood cells. They’re red or orange-yellow in color and are typically found when people have conditions that cause kidney bleeding.
• White blood cell (WBC) casts: WBC casts are made up of white blood cells. Often, WBC casts are the result of infections that have reached the kidneys.
• Bacterial casts: Bacterial casts can also signal infection. Sometimes, a bacterial casts are found mixed in with WBC casts.
• Fatty casts: Fatty casts are made up of lipids. When lipids are present in the urine, it can be a sign of kidney dysfunction.
• Renal tubular epithelial casts: Renal tubular epithelial casts are composed of epithelial cells, like skin cells and the cells that line your organs. They can be caused by conditions that cause these cells to die off and clump.
• Pigment casts: Pigment casts are known for their colors. They’re often caused by taking medication and don’t typically indicate any conditions.
• Granular casts. Granular casts are similar to hyaline casts, but they’re associated with more cell breakdown and are more likely to result from chronic kidney disease.
• Waxy casts. Waxy casts are advanced granular casts with significant cell breakdown.

What is the most common type of cast seen in urine?

Hyaline casts are the most common type of cast seen in urine.

While most other casts are the result of serious infections or chronic diseases, these casts can be caused by dehydration and intense exercise.

This means they can be found in the urine of otherwise healthy people, making them much more common than other types of urinary casts.