Microscopic Examination of Urine Sediment
12mL
volume of urine recommended for urinalysis
10-15mL
volume range of urine recommended for urinalysis
1 mL
amount of sediment obtained
RBCs, WBCs, and casts
components that should be counted and classified
crystals, bacteria, and mucus
components that should be assessed qualitatively
10 LPF or HPF
minimum fields assessed for urine components depending on specific components
supra vital stains
used to enhance visualization
crystal-violet and safranin (Sternheimer-Malbin)
most common supra vital stain for urine
0.5% toluidine blue solution
distinguishes various cell components differently to help in identification
acetic acid
brings out nuclear detail of WBCs and lyses RBCs
Sudan III and oil red O
fat stains that identify fat inside cells or free floating; within renal cells or macrophages (oval fat bodies)
cholesterol
does not stain and must be confirmed with polarizing microscopy
gram stain
used to identify bacteria and yeast; rarely used in UA
Prussian blue
stains iron in hemosiderin granules blue; can be free floating or inside cells
Hansel stain
methylene blue and eosin-Y; for identification of eosinophils
brightfield
most commonly used microscope technique in urinalysis
phase-contrast
ideal for urine sediments; allows more detailed visualization of RBC morphology and translucent or low-refractive components and living cells
polarizing
confirms presence of cholesterol; also used on crystals
cholesterol
forms a maltese cross pattern with polarized light
interference contrast
gives 3-D images; high cost
cytocentrifugation
a technique used to produce permanent microscope slides of urine sediment and body fluids; produces a monolayer of sediment components
pictures
pg 132-3. 192-210, Table 7.5 pg. 137, ph 140, 144-5
0-3/HPF
red blood cell reference interval
0-8/HPF
white blood cell reference interval
0-2/LPF
hyaline cast reference interval
few/LPF
squamous epithelial cell reference interval
few/HPF
transitional epithelial cell reference interval
few (0-1)/HPF
renal epithelial cell reference interval
negative/HPF
bacteria and yeast reference interval
non/LPF
abnormal crystal reference interval
10x
LPF
40x
HPF
erythrocytes
small, biconcave disks, approximately 8um in diameter and 3um deep with no nucleus
crenated
RBC hypertonic (concentrated) urine
ghost cells
RBC hypotonic (dilute) urine
hypertonic
concentrated urine
hypotonic
dilute urine
renal bleed
increased RBC casts and significant protein
bleeding below kidney or contamination
increased RBCs no casts or protein
RBCs lysed or false positive
positive strip test no RBCs seen; false positive
vitamin C or look-alike (yeast, crystals, bubbles)
false negative RBC strip test
neutrophils
most common WBC in blood and urine
glitter cells
WBCs in hypotonic urine
degenerated blebs
WBCs in hypertonic urine
upper urinary tract infection
WBCs, WBC casts along with positive protein
lower urinary tract infection
increased WBCs, no casts and no protein (or lower level)
leukocyturia
increased WBCs in urine
eosinophiluria
predictor of acute interstitial nephritis due to drug sensitivity
Hansel stain
used to detect eosinophils
lymphocyturia
seen in viral infections kidney transplant rejection
histiocytes
monocytes and macrophages
squamous epithelial cells
the most common and largest of the epithelial cells; use low power; rarely significant, usually caused by contamination
transitional (urothelial) epithelial cells
line calyces, renal pelvis, ureters, and bladder; various size and shape; seen in UTI, urinary procedures, and carcinoma (in sheets)
renal tubular epithelial cells
convoluted tubular and collecting duct cells enumerated; seen in acute ischemic or toxic renal tubular disease from heavy metals or drug (ahminoglycosides) toxicity
casts
formed in distal and convoluted tubules with a core matrix of uromodulin (Tamm-Horsfall protein) secreted by renal tubular cells; seen in acidic urine
hyaline or finely granular
types of casts that are normal in small amounts
hyaline casts
most commonly observed casts in the urine sediment; two or few/lpf are normal; seen in excess in strenuous exercise, dehydration, fever, emotional stress, CHF, and renal disease
waxy casts
indicates prolonged stasis (take as long as 48 hours or more to form) and tubular obstruction; believed to be advanced stages of other casts; found in chronic renal failure, acute renal disease, hypertension, and renal allograft rejection
red blood cell casts
casts diagnostic of intrinsic renal disease; most often of glomerular origin, but may result from tubular damage; accompanied by proteinuria
proteinuria
must accompany increased numbers or abnormal casts
WBC cast
casts that indicates renal inflammation or infection
granular casts
casts composed primarily of uromodulin protein; not usually clinically significant casts unless they are very broad which may indicate poor prognosis; may be formed by degradation of other cellular casts
fatty casts
casts with oval fat bodies indicating renal tubular death; signify a severe renal pathological condition, accompanied by significant proteinuria
casts
must be correlated with chemical tests
mucous threads, fibers, and crystals
three cast look-alikes
crystals
result of precipitation of urine solutes, not usually present in freshly voided urine; significant in fresh voided indicates tubular damage
concentration of urine, urine pH, and slow flow of urine
factors influencing crystal formation
amorphous urates, acid urates, monosodium urate, uric acid, calcium oxalate
crystals present in acidic urine
amorphous phosphates, triple phosphate, calcium and magnesium phosphates, ammonium bitrate, calcium carbonate
crystals present in alkaline urine
bilirubin, cystine, tyrosine and leucine, cholesterol
crystals present in metabolic conditions
drug crystals, bacteria, yeast, trichomonads, Gardnerella, parasites, fat, lipidemia, mucus, hemosiderin, sperm
crystals present in iatrogenic origin
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amorphous urate crystals
present in urine 5.7-7.0; have no clinical significance; may appear as brick dust due to uroerythrin
acid urate crystals
sodium, potassium, and ammonium salts of urine acid that appear as small yellow-brown balls or spheres; no clinical significance
uric acid crystals
occur in many forms, most common is rhombic or diamond shape, also cubes, barrels, or bands and can form rosettes; appear only when urine pH is less than 5.7; commonly seen in gout or after cytotoxic drug administration
monosodium urate crystals
appear as colorless to light-yellow slender, pencil-like prisms; no clinical significance
calcium oxalate crystals
most frequently observed crystals in human urine; form at any pH, commonly formed in high ascorbic acid diets or during refrigeration; seen in ethylene glycol (antifreeze ingestion) and during severe chronic renal disease; envelope crystals
amorphous phosphates
found in alkaline and neutral urine; indistinguishable from amorphous urates; precipitate appears white or gray; no clinical significance
triple phosphate
colorless and appear in different forms; most common is coffin lid; found in alkaline or neutral urine; little clinical significance, but found in conjunction with UTIs
calcium and magnesium phasphates
common and have no clinical significance; found in neutral and slightly alkaline (sometimes slightly acidic) urine
ammonium biurate
thorny apple appearance (yellow brown spheres with striations on surface); normal urine solute seen after storage; significant in fresh urine indicating renal tubular damage
calcium carbonate
appear as tiny, colorless granular crystals usually found in pairs or tetrads; no frequently found and no clinical significance
bilirubin crystals
indicate large amounts of bilirubin in the urine; only form in acidic urine; appear as small clusters of fine needles
cystine
colorless, hexagonal plates with uneven sides; present primarily in acidic urine; clinically significant indicating disease (hereditary cystinosis or cystinuria);
tyrosine and leucine
form in acidic urine and dissolve in alkaline urine; rarely seen but indicate abnormal process such as severe liver disease or a rare inherited metabolic disorder
cholesterol
clear, thin parallelogram plates with notched corners; indicate large amounts of cholesterol and ideal conditions that allowed them to precipitate out into the urine; usually accompany oval fat bodies, fatty casts, and large amounts of protein; signify nephrotic syndrome, kidney disease
iatrogenic crystals
form due to treatment administered such as drugs, dyes, contrast media
rod-shaped bacili
most common bacteria in urine
bacteria
presence indicates UTI (accompanied by leukocytes) or contamination; reported as few, moderate, or many per HPF
yeast
colorless ovoid cells resembling RBCs; seen often as vaginal contaminant
KOH prep
prepared to view yeast
Trichomonads vaginalis
most common cause of parasitic gynecologic infection in females as an STD; turnip-shaped flagellates and have jerky motility in wet preps; reported as present
Gardnerella vaginalis
an anaerobic bacterium; clue cells present; characteristic of bacterial vaginosis
clue cells
squamous epithelial cells from the vaginal mucosa with large numbers of bacteria adhering to them
parasites
common are Enterobius vermicularis (pinworm), Giardia lamblia and Schistosoma haematobium (schistosomiasis)
mucus
a protein produced by the renal tubular epithelium; no clinical significance
fat
found in urine in three forms; free-floating droplets, oval fat bodies, or within fatty casts; triglycerides and/or cholesterol
triglycerides
will stain with Sudan III or an oil red O stain
cholesterol
will not stain, but will demonstrate birefringence with polarizing microscopy
cholesterol droplets
produce a distinctive maltese cross pattern
lipiduria
always clinically significant; present in a variety of renal diseases and may occur after severe crush injuries; always accompanied by proteinuria
hemosiderin
form of iron that results in ferritin denaturation; may be seen in urine after a severe hemolytic episode (transfusion reaction); Prussian blue used to identify
sperm
indicates ejaculation or recent sexual intercourse
fibers
hair, cotton, fabric threads, diapers and hygiene products often appear in urine sediment
starch
originate from body powders or gloves; not perfectly round with a centrally located dimple; exhibits pseudo-maltese pattern with polarized microscopy
fecal matter
come from improper collection or through abnormal connection between urinary tract and the bowel
correlation
process of using entire analysis: physical, chemical, and microscopic
disease process, functional change, hereditary disease, or iatrogenic agent
purposes of findings in urine sediment