Sediment Analysis Flashcards
what is the core protein of urinary casts? Two names, former and new
Used to be called Tamm-Horsfall; now uromodulin
where are urinary casts formed?
the lumen of the renal tubule
In urinalysis, squamous epithelial cells with large numbers of bacteria adhering are termed?
clue cells
Under what type of microscopy do cholesterol droplets in urine exhibit a Maltese cross pattern?
polarizing
what are oval fat bodies?
either renal tubule epithelial cells which have absorbed fat droplets that escaped through the glomerular membrane, or macrophages containing the lipids which are larger than the RTEs
why are oval fat bodies clinically significant?
they indicate a damaged glomerular basement membrane; should report in number per HPF
How do cholesterol droplets in lipiduria appear under polarizing microscopy?
as 4 quadrants with a “Maltese cross” pattern
what do cholesterol crystals in urine represent?
crystallized free cholesterol in the urine
name some conditions that could cause oval fat bodies or fatty hyaline casts?
nephrotic proteinuria, polycystic kidney disease, Fabry disease
what is the most used supravital (stains living cells) stain of urine sediment?
Sternheimer-Malbin- for id’ing blood cells, casts and other formed elements
what is a Sedi-stain
a modified Sternheimer-Malbin, stabilized
what is the usefulness of Sudan III or Oil Red-O stains?
confirms present of fat in urine, orange or red stain
what is Prussian blue used to identify in urine?
hemosiderin, which can be free-floating or in epithelials or casts
this stain aids in i.d. of eosinophils in urine
Hansel stain- methylene blue and eosin-Y plus methanol
what does toluidine blue stain aid in the identification of?
white blood cells versus renal tubular epithelial cells
what type of microscopy can entail a difficulty to identify low-refractile constituents of urine and what can help?
brightfield; can use lower light OR USE PHASE CONTRAST instead
name some difficult to view elements of urine and what microscopy can enhance viewing
hyaline casts, RBC ghost cells, and bacteria: phase-contrast microscopy
what can appear similar to cholesterol under polarizing microscopy and what clues you that it is not?
starch granules and some drug-induced crystals can appear as pseudo-Maltese cross but have quadrants of UNEQUAL SIZE.
what are the components of the Sternheimer-Malbin stain? what kind of stain is it?
crystal violet and safranin; it’s a supravital stain
what components of urine do NOT polarize light?
RBCs, casts, mucus, bacteria, cells, cell debris such as mmbrn phospholipids
what urine components DO POLARIZE light?
monohydrate calcium oxalate crystals, fibers, amorphous crystals urates strongly, phosphates weakly or negatively; cholesterol and starch granules
what is in the HAnsel stain?
methylene blue and eosin-Y in methanol
what type of microscopy is good for translucent/ low refractility components such as hyaline casts. bacteria, ghost RBCs?
phase contrast
what is polarizing microscopy best for viewing?
fat, esp cholesterol, in urine
are casts in urine normal? what about transitional and squamous cells?
0 to 2 per LPF only; yes, a few
how would you differentiate yeast from RBCs in urine?
yeast varies in size more, and tends to be spherical or ovoid not biconcave; also, it often has BUDDING
If lotion or oil contaminates a urine specimen, it can mimic RBC appearance. Differentiate:
the droplets will vary in size but look uniform otherwise and be highly refractile. The chemical blood test will be negative
what can cause ghost RBCs?
dilute and/or alkaline urine, bc it can cause hemoglobin to leak and leave a pale empty membrane
how do RBCs appear in hypertonic urine?
crenated, they dehydrate. “burr cell-like”.
how do renal collecting duct cells appear diff from WBCs in brightfield viewing?
they have polygonal shape
what are glitter cells and in what type of urine sample found?
swollen spherical WBCs with refractile cytoplasmic granules; found in hypotonic urine
two ways to confirm lipid inclusions in urine?
polarizing microscopy, or fat stains like Sudan III or Oil Red
When may transitional epithelial cells increase in urine samples?
with UTI or inflammation; can see SHEETS of them after procedures such as catheterization or cystoscopy
other name for transitional cells
urothelial
what are decoy cells? why so named?
transitional or renal tubular cells infected with the polyomavirus of the BK strain, BKV; potential mis-ID as malignant
describe a decoy cell
“comet like” transitional or renal epithelial cell infected with Polyomavirus, BKV. Nucleus eccentric, abnormal chromatin (ground glass), cytoplasmic vesicles
difference in appearance between spherical urothelial cells and tubular epithelial cells:
former have central nucleus, latter is eccentric
what is the most commonly seen cast in urine sediment? what is it composed of?
hyaline casts, low refractility, made mainly of a homogenous uromodulin protein matrix
what is a normal number of hyaline casts and when may it be increased?
two or fewer is normal. Increases mayb occur from extreme stress, exercise, dehydration, or accompanying pathologic casts in other diseases
what is a major difference between hyaline and waxy casts on brightfield ?
waxy casts have a high refractive index so are readily visible, with well defined edges and possible blunt or sharp or uneven ends
how do waxy casts appear differently than hyaline with a Sternheimer-Malbin stain?
they are a darker pink with a diffuse ground-glass look; also more broad from being in a dilated tubule
what do waxy casts imply?
prolonged stasis and tubular obstruction; they represent an advanced stage of the other casts types (hyaline, granular, cellular) that are transformed during stasis over 48 hours
In whom are waxy casts most frequent?
pts with chronic renal failure; also in acute or in malignant hypertension
what kind of inclusions can be found in casts?
RBCs, WBCs, renal tubular cells, mixed cells, bacterial casts
before reporting an RBC cast what must be observed floating in the sediment?
free-floating RBCs
what are muddy brown casts aka and how formed?
blood casts, form if urine stasis is sufficient then the RBC casts degenerate into pigmented granular casts
how do WBC casts appear diff than RBC?
cells are more refractile and readily apparent
what do oval fat bodies in fatty casts indicate?
renal tubular cell death, a significant pathologic condition
what should each be accompanied by on the chemical tests: RBC casts, leuko casts, bile-pigmented casts
RBC casts: chem blood positive or accounted for if negative before reporting the cast. Leukocyte casts: may have + leuko esterase, nitrite form bacteriuria. Bile pig: pos chem bilirubin , or for Hmg/myoglobin, + for blood
When are urine crystals always cilnically significant?
in freshly voided urine, bc that means they formed in vivo, not on standing. Crystals formed in nephrons can cause damage
what helps ID look-alike crystals?
the pH at which they are present
What are normal crystals in acid urine; and in alkaline….
acid: amorphous urates (yellow-brown grans, pink sediment), uric acid, and calcium oxalate
alkaline: amorphous phosphates (white ppt in urine), triple phosphate, ammonium biurate, calcium carbonate
how do triple phosphate crystals appear?
“coffin lid”, 3 to 6 sided prisms
how do acid urate crystals appear? when are they present, and what often misidentified as?
small yellow-brown balls, can be mistaken for leucine crystals; present in neutral to slight acidity but not usually in fresh urine
acid urates dissolve at?
60 C
describe monosodium urate crystals
colorless to light yellow, narrow pencil like, can be in small clusters, ends not pointy. Present in acid pH
most common uric acid crystal shapes:
rhomoid/diamond, or cubes, barrels, or clustered into rosettes, with lamination
uric acid crystal color
yellow to golden brown
describe the two calcium oxalate crystal forms
monohydrate: small and ovoid (barrelish)
dihydrate: “envelope”/ octahedral forms
what about the small calcium oxalate crystals help distinguish them from RBCs?
thy are strongly birefringent under polarizing microscopy
what kind of poisoning may cause calcium oxalate crystals?
antifreeze
differentiate calcium phosphate and magnesium phosphate crystals. Both grow in alkaline or neutral urine
Ca: occur as dibasic with rosettes of wedges or bundles of needles, colorless, or monobasic as sheets
Mg: large colorless, elongated rectangular or rhomboid
