Study cards
Urinalysis and Other Body Fluids
24 cards from 2 lessons in Urinalysis and Other Body Fluids, each linking to the passage it came from.
Turn the cards
Click the card to turn it. Then → Got it or ← Not yet. A card marked Not yet comes back before the round ends.
Every card turned
All cards
Urine Microscopy: Cells, Casts, Crystals, and Artifacts
Which optical method helps reveal hyaline casts and dysmorphic red cells in unstained urine?
Phase-contrast microscopy.
It improves the contrast of particles that are hard to see with routine bright-field illumination.
What shape identifies an acanthocyte in urine, and what bleeding source does it support?
A ring-shaped red cell with membrane blebs, which supports a glomerular source.
Report acanthocytes together with the other dysmorphic red cells, the protein result, and any casts. Examine a fresh specimen, because crenation in concentrated urine can mimic them.
What does a leukocyte cast show that free leukocytes alone cannot?
That the inflammation is inside the kidney.
The cells were packed into a cast inside the tubules, which places the inflammation in the kidney. Culture and the other urine findings identify the cause.
Which site of bleeding does an RBC cast support?
Bleeding within the nephron, often glomerular.
The red cells are enclosed in a cast matrix that forms within the tubules.
Which protein forms the main matrix of urinary casts?
Uromodulin.
Its fibrils aggregate into casts in distal tubules and collecting ducts.
Name a physiologic setting in which hyaline casts can occur.
Concentrated urine, dehydration, or recent strenuous exercise.
Hyaline casts alone do not establish renal disease.
Can squamous epithelial cells alone prove that a urine specimen is contaminated?
No.
Abundant squamous cells, especially with bacteria and mucus, suggest genital or distal urethral material, but they cannot show which cultured organisms are contaminants.
What process do increased renal tubular epithelial cells and their casts support?
Tubular injury.
The cells place the injury in the tubules without showing whether ischemia, a drug, or a toxin caused it.
What is an oval fat body?
A lipid-filled renal tubular cell or macrophage.
It supports lipiduria and heavy protein loss, especially when fatty casts and marked proteinuria are also present.
Which feature helps distinguish yeast from a round particle that resembles a red cell in urine?
Budding.
Pseudohyphae also support identifying yeast.
What urine crystal shape suggests cystine?
Colorless hexagonal plates.
Confirm suspected cystine with the cyanide-nitroprusside test or amino acid analysis, because hexagonal uric acid crystals can look the same.
Read the passage: Clinically significant and drug-associated crystals
What structural feature do you look for before calling an elongated particle a cast?
A continuous matrix enclosing the structure.
Fibers, mucus, and crystal aggregates can imitate the outline.
Body Fluid Cell Counts and Cerebrospinal Fluid
Set up the formula for a manual chamber cell concentration in cells/µL.
Cells counted × dilution factor ÷ (area counted in mm² × chamber depth in mm).
Area × depth gives the counted volume, and 1 mm³ equals 1 µL.
Which two chamber dimensions determine the volume represented by a count?
The counted area and chamber depth.
Multiplying mm² by mm gives mm³, which is numerically equal to µL.
When counts from both chamber sides are added, which volume belongs in the denominator?
The combined counted volume of both sides.
Using one side's volume with pooled cells would double the calculated concentration.
Why can a very low CSF cell concentration require manual confirmation of an automated result?
It may lie near or below the analyzer's verified quantification limit.
Automated body-fluid counts lose accuracy near their lower limit, so the laboratory sets a count below which a manual chamber count is done.
Read the passage: Selecting and controlling a cell-count method
Name two ways cytocentrifugation can change a body-fluid preparation.
Cell loss and morphologic distortion.
Spin time, centrifugal force, and specimen volume change recovery and appearance, and the distortion can resemble abnormal cells.
Can a clear, colorless CSF appearance exclude disease?
No.
Clear CSF can still contain an abnormal cell count, organisms, or malignant cells, so cell counts, chemistry, Gram stain, and culture are still needed.
Can normal CSF cells, glucose, and protein exclude a shunt-associated infection?
No.
Device-associated infection can cause little inflammation, so culture is still needed to detect it.
What does a negative CSF Gram stain mean when infection is suspected?
It does not exclude infection.
Gram stain sensitivity is limited, including after antimicrobial exposure.
What can CSF culture provide that a molecular panel alone cannot?
Recovery of an organism for further identification and susceptibility testing.
A panel finds only the targets on its list. Culture recovers the organism itself as an isolate for further work.
Which paired result is needed to interpret a CSF-to-blood glucose ratio?
Blood glucose collected close to the lumbar puncture.
CSF glucose follows blood glucose, so the blood level and the timing of both collections affect the comparison.
Why are serum and CSF compared when assessing oligoclonal IgG bands?
To distinguish shared bands from bands restricted to CSF.
CSF-restricted bands show antibody made inside the central nervous system, which occurs in multiple sclerosis and in several infections and inflammatory diseases.
Set up the IgG index using paired CSF and serum measurements.
(CSF IgG ÷ serum IgG) ÷ (CSF albumin ÷ serum albumin).
Use the same unit within each ratio, and interpret the result against the performing laboratory's reference interval.
These cards are also free to download for Anki: see Anki decks.