Casts found in Urine

Urinary casts are tube-shaped particles, and most are transparent, making them difficult to spot. Casts form inside the kidneys' nephrons, microscopic tubes for filtering blood. Casts are mostly made from protein but can accumulate other cells and fat particles. A cast's composition can determine its type as either cellular or non-cellular (acellular).

Cellular casts are made from protein and contain white blood cells, red blood cells, or epithelial cells. Non-cellular casts are made from protein and can contain fat. Hyaline, fatty, granular, and waxy casts are all non-cellular casts.

Cellular casts, fatty casts, granular casts, and waxy casts are not normally present in urine, so their presence could indicate the patient has kidney problems.

Hyaline casts are made from only protein and can typically be found in low numbers in urine, with 0 to 4 casts per high-powered field. Larger numbers of hyaline casts could indicate dehydration, physical exertion, fever, or kidney disease.

Microscope images of casts. The renal tubular epithelial cast is a transparent rounded rectangle. The muddy granular cast is a brown oval. The white blood cell cast is a transparent rounded rectangle containing transparent circles. The red blood cell cast is a rounded rectangle containing red circles.

Figure 1: Casts found in urine under the microscope. A) Renal tubular epithelial cell cast. B) Muddy granular cast. C) White blood cell cast. D) Red blood cell cast. E) Another cast.

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Microscopic Analysis of Urine