1URINALYSIS

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UA Casts

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Cast Formation

Urinary casts are formed only in the distal convoluted tubule (DCT) or the collecting duct (distal nephron). The proximal convoluted tubule (PCT) and loop of Henle are not locations for cast formation. Hyaline casts are composed primarily of a mucoprotein (Tamm-Horsfall protein) secreted by tubule cells. The Tamm-Horsfall protein secretion (green dots) is illustrated in the diagram below, forming a hyaline cast in the collecting duct:

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Cast Formation

• Cast are molded in the lumen of the renal tubules

• Formed in Distal and Collection tubules

• Composed of plasma proteins of Glomerular Filtrate

• Tamm-Horsfall Protein makes up matrix

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Cast Names

• Named by how they appear

• Convoluted

• Broad

• Granular (Finely or Coarsely granular)

• Waxy

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Cast Names

• Named by what is in casts

• Cells WBC, RBC, Renal Epithelial or Mixed

• Substances Fat Hemoglobin

7Casts

8Fiber

Don’t mistake fibers for casts!!!!

9Hyaline Casts

Low refractive Index

Difficult to see

Use low light

10Hyaline Casts

Cylindroid

Hyaline cast with tail

11Hyaline Cast

Mucous Threads

Phase Contrast

12Hyaline Cast

Spermatozoa

Tortuouse

Cigar Shaped

Phase Contrast

13Hyaline Cast

Tortuous

Interference Contrast

14Hyaline Cast

• Hyaline Cast• Triple Phosphate• Note how

Hyaline Casts are barely visible

15Hyaline Cast

• Convoluted• Note cells on

matrix

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Granular Casts

• Formed by the breakdown of cellular casts

• In patients with renal disease the granules become more fine as they progress through the nephron and eventually become Waxy

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Cast Degeneration

18Finely Granular Cast

• C

19Finely Granular Cast

• Higher refractive index than Hyaline cast

• May be present in urine of healthy person after severe physical exercise

• Found in all forms of renal disease

20Coarse Granular Cast

• Granules may be disintegrated RBC’s due to reddish color

21Coarse Granular Cast

• Sternheimer-Malbin Stain

22Coarse Granular Cast

23Coarse Granular Cast

Note mucous threads in background

24Broad Finely Granular Cast

In early stage of evolving into waxy cast

Notched margins

25Waxy Cast

• High Refractive Index

• Notched parallel margins

• “Broken Off” ends

• Chronic renal disease

26Waxy Cast

• High Refractive Index

• Notched parallel margins

• “Broken Off” ends

• Chronic renal disease

27Waxy Cast

• High Refractive Index

• Notched parallel margins

• “Broken Off” ends

• Chronic renal disease

28Waxy Cast

SM Stain• High Refractive

Index• Notched parallel

margins• “Broken Off”

ends• Chronic renal

disease

29Waxy Cast

• Note Spheric lipid globules on surface

• Notched parallel margins

• “Broken Off” ends

• Chronic renal disease

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Fatty Casts

• Casts that contain free fat or oval fat bodies

• Fat appears as globular lipids of varying size

• Often have a yellow tan color

• Lipid has high refractive index

• Lipid is birefringent

• Maltese Cross in polarized light

31Fatty Cast

• Lipid globules on surface

• RBC in background

• Nephrotic Syndrome

32Fatty Cast

• Lipid globules on surface

• RBC in background

• Nephrotic Syndrome

• Polarized Maltese Cross

33Fatty Cast

• Lipid globules on surface

• RBC in background

• Nephrotic Syndrome

• Polarized Maltese Cross

34Fatty Cast

• Lipid globules on surface

• RBC in background

• Nephrotic Syndrome

• Polarized Maltese Cross

35Fatty Cast

• Lipid globules on surface

• RBC in background

• Nephrotic Syndrome

36Fatty Cast Polarized

37Broad Red Cell Casts

38Cast Formation in Nephron

Cellular Cast are named for the types of cells they contain

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Cellular Cast formation

40Hemoglobin Cast ??

• Reddish color

41RBC Cast

• RBC in hyaline cast matrix

• RBC more concentrated at one end

42RBC Cast

• RBC in hyaline cast matrix

• Surrounding urine filled with PMN’s and RBC

43RBC Cast

• RBC in hyaline cast matrix

44RBC Cast

• RBC in hyaline cast matrix

• Very difficult in this cast to see intact RBC’s

• Hb granules

45Cellular Cast Mixed

• Epi’s• WBC• Note yeast

46Cellular Cast

• Renal Tubular Cells

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Cast Review

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Casts Overhead