Microscopic Examination of Urine - Casts Flashcards
Casts can be found in?
Only the kidneys.
Casts are formed in:
The distal convoluted tubule and collecting ducts.
What protein is responsible for the formation of hyaline casts?
Tamm-Horsfall (uromodulin).
What makes us a cast?
A matrix of Tamm-Horsfall protein (uromodulin) and cells, proteins, or fats incorporated in the matrix.
What factors promote casts?
- Urinary stasis.
- Acid pH.
- High solute concentration.
What is the primary criteria for cast morphology?
- Parallel sides.
- Rounded or straight edge.
- Uniform diameter.
- Definite outline.
How are casts identified?
- Reduce light.
- Search with 10X.
- Identify type with 40X.
- Phase or interference microscopy.
- Staining.
What are the clinical significance of casts?
- Reflect status of tubules.
- “Biopsy” of renal tubule.
- Types and numbers indicate specific diseases.
- Can be increased with after exercise.
What is the morphology of a hyline cast?
- Semitransparent, nonrefractile, homogenous.
- Hard to see.
- Sometimes cylindroid or convoluted.
What color are hyaline casts stained?
Pink
What color are hyaline casts?
Colorless
How many are normally seen lpf?
0-2
Presence of hyaline casts could mean:
- Renal disease.
- Dehydration, fever, heat exposure, emotional distress.
- congestive heart failure.
What do hyaline casts get mistaken for?
Mucous threads.
What do hyaline casts get mistaken for?
Mucous threads.
Is it normal to find cellular casts?
No
What color are RBC casts?
- Yellow to red-brown.
- Orange red homogenous.
- Dirty brown and granular.
What color are RBC casts stained?
Lavender
What is the clinical correlation of RBC casts?
- Glomerular bleeding.
- Upper UTI.
- Diagnostic of renal disease.
If RBC casts are present, what correlation will be on the chem strip?
Positive for protein and blood.
What is the clinical significance of WBC casts?
- Indicate interstitial inflammation or infection.
- Upper UTI, not lower.
WBC casts can be mistaken for:
Pseudocast
The presence of WBC casts will need to be correlated with:
- Bacteria.
- Protein.
- Hematuria.
- Red cell casts also if glomerular.
What is the clinical significance of Renal tubular epithelial casts?
- It’s not normal.
- Indicates advanced destruction.
- Associated with toxic chemicals or viral infections.
- Also find proteinuria and granular casts.
What is the composition of granular casts?
- Degenerated cells.
- Products excreted by RTE cells.
- Aggregates of plasma proteins.
What is the clinical significance of non-pathological granular casts?
These are lysosomes from RTE and are no cause of concern.
What is the clinical significance of pathologic granular casts.
- Degenerated cell casts.
- Aggregated proteins filtered by the glomerulus.
- Indicate stasis.
What is the composition of fatty casts?
- Oval fat bodies and/or free fat globules.
- Hyaline or granular matrix.
- May be other cells.
What is the morphology of fatty casts?
Globules vary, and refractive.
What color are fatty casts?
Light yellow or brown.
Triglycerides and neutral fatty casts will test _______ on a fat stain and ______ on maltese cross.
Positive on fat stain and negative on maltese cross.
Cholesterol and esters will test ______ on a fat stain and ______ on maltese cross.
Negative on fat stain and positive on maltese cross.
What is the clinical significance of a fatty cast?
- Severe renal disease.
- Proteinuria.
What color are waxy casts?
Colorless, gray, yellow.
What color does a waxy cast stain?
Darker pink.
What is used to stain a waxy cast?
Sternheimer
What is the clinical significance of waxy casts?
- Serious trouble.
- Imply tubular obstruction and prolonged stasis.
- Chronic renal disease.
- Renal graft rejection.
- Malignant hypertension.
- Some acute renal diseases.
Broad casts mean:
Severe renal stasis.
What cast has the nickname of “Renal failure” cast?
Broad cast.
Bacterial casts is diagnostic of:
Pyelonephritis.
Bacterial casts are mistaken for:
Granular casts.
Bacterial casts can be correlated with?
Bacteria and WBC.
Hemosiderin casts can be stained with?
Prussian blue.
