Microscopic Examination of Urine - Casts

Question 1

Casts can be found in?

Answer 1

Only the kidneys.

Question 2

Casts are formed in:

Answer 2

The distal convoluted tubule and collecting ducts.

Question 3

What protein is responsible for the formation of hyaline casts?

Answer 3

Tamm-Horsfall (uromodulin).

Question 4

What makes us a cast?

Answer 4

A matrix of Tamm-Horsfall protein (uromodulin) and cells, proteins, or fats incorporated in the matrix.

Question 5

What factors promote casts?

Answer 5

• Urinary stasis.
• Acid pH.
• High solute concentration.

Question 6

What is the primary criteria for cast morphology?

Answer 6

• Parallel sides.
• Rounded or straight edge.
• Uniform diameter.
• Definite outline.

Question 7

How are casts identified?

Answer 7

• Reduce light.
• Search with 10X.
• Identify type with 40X.
• Phase or interference microscopy.
• Staining.

Question 8

What are the clinical significance of casts?

Answer 8

• Reflect status of tubules.
• “Biopsy” of renal tubule.
• Types and numbers indicate specific diseases.
• Can be increased with after exercise.

Question 9

What is the morphology of a hyline cast?

Answer 9

• Semitransparent, nonrefractile, homogenous.
• Hard to see.
• Sometimes cylindroid or convoluted.

Question 10

What color are hyaline casts stained?

Answer 10

Pink

Question 11

What color are hyaline casts?

Answer 11

Colorless

Question 12

How many are normally seen lpf?

Answer 12

0-2

Question 13

Presence of hyaline casts could mean:

Answer 13

• Renal disease.
• Dehydration, fever, heat exposure, emotional distress.
• congestive heart failure.

Question 14

What do hyaline casts get mistaken for?

Answer 14

Mucous threads.

Question 15

What do hyaline casts get mistaken for?

Answer 15

Mucous threads.

Question 16

Is it normal to find cellular casts?

Answer 16

No

Question 17

What color are RBC casts?

Answer 17

• Yellow to red-brown.
• Orange red homogenous.
• Dirty brown and granular.

Question 18

What color are RBC casts stained?

Answer 18

Lavender

Question 19

What is the clinical correlation of RBC casts?

Answer 19

• Glomerular bleeding.
• Upper UTI.
• Diagnostic of renal disease.

Question 20

If RBC casts are present, what correlation will be on the chem strip?

Answer 20

Positive for protein and blood.

Question 21

What is the clinical significance of WBC casts?

Answer 21

• Indicate interstitial inflammation or infection.

- Upper UTI, not lower.

Question 22

WBC casts can be mistaken for:

Answer 22

Pseudocast

Question 23

The presence of WBC casts will need to be correlated with:

Answer 23

• Bacteria.
• Protein.
• Hematuria.
• Red cell casts also if glomerular.

Question 24

What is the clinical significance of Renal tubular epithelial casts?

Answer 24

• It’s not normal.
• Indicates advanced destruction.
• Associated with toxic chemicals or viral infections.
• Also find proteinuria and granular casts.

Question 25

What is the composition of granular casts?

Answer 25

- Degenerated cells. - Products excreted by RTE cells. - Aggregates of plasma proteins.

Question 26

What is the clinical significance of non-pathological granular casts?

Answer 26

These are lysosomes from RTE and are no cause of concern.

Question 27

What is the clinical significance of pathologic granular casts.

Answer 27

- Degenerated cell casts. - Aggregated proteins filtered by the glomerulus. - Indicate stasis.

Question 28

What is the composition of fatty casts?

Answer 28

- Oval fat bodies and/or free fat globules. - Hyaline or granular matrix. - May be other cells.

Question 29

What is the morphology of fatty casts?

Answer 29

Globules vary, and refractive.

Question 30

What color are fatty casts?

Answer 30

Light yellow or brown.

Question 31

Triglycerides and neutral fatty casts will test _______ on a fat stain and ______ on maltese cross.

Answer 31

Positive on fat stain and negative on maltese cross.

Question 32

Cholesterol and esters will test ______ on a fat stain and ______ on maltese cross.

Answer 32

Negative on fat stain and positive on maltese cross.

Question 33

What is the clinical significance of a fatty cast?

Answer 33

- Severe renal disease. | - Proteinuria.

Question 34

What color are waxy casts?

Answer 34

Colorless, gray, yellow.

Question 35

What color does a waxy cast stain?

Answer 35

Darker pink.

Question 36

What is used to stain a waxy cast?

Answer 36

Sternheimer

Question 37

What is the clinical significance of waxy casts?

Answer 37

- Serious trouble. - Imply tubular obstruction and prolonged stasis. - Chronic renal disease. - Renal graft rejection. - Malignant hypertension. - Some acute renal diseases.

Question 38

Broad casts mean:

Answer 38

Severe renal stasis.

Question 39

What cast has the nickname of "Renal failure" cast?

Answer 39

Broad cast.

Question 40

Bacterial casts is diagnostic of:

Answer 40

Pyelonephritis.

Question 41

Bacterial casts are mistaken for:

Answer 41

Granular casts.

Question 42

Bacterial casts can be correlated with?

Answer 42

Bacteria and WBC.

Question 43

Hemosiderin casts can be stained with?

Answer 43

Prussian blue.