ch 7 Flashcards
recommended volume to centrifuge urine
400-450 g
(sternheimer-malbin)
crystal-violent and safranin
–> enhances visualization
prefrerred
acetic acid staining
brings out nuclear detail of WBCs and lyses RBCs
–> visualizes WBS
fat stains
sudan III or oil red O
–> identify fats inside cells or free floating
gram stain
identifies bacteria and yeast (not used for urinalysis
prussian blue stain
stains iron in hemosiderin granules blue
hansel stain
methylene blue and eosin-Y
–> identifies eosinophils
microscopy techniques
brightfield, phase contrast, polarizing, interference contrast
brightfield microscopy
most commonly used (black and white)
phase contrast
ideal for urine sediments as it allows for more detailed visualization of translucent components and living cells
polarizing
confirms presence of cholesterol
–> used on crystals
interference contrast
three dimensional images, but high cost prevents use by most laboratories
formed elements
not all formed elements are abnormal
–> large amounts is diagnostically significant
RBCs
biconcave disks
–> normal RBC is less than 3 per hpf
increased RBC can mean
with casts: renal bleeding
no casts: bleeding below kidney
positive strip test for blood with no RBCs visible
RBC were lysed –> hemoglobin tests are positive
false positive
false negative strip test for blood with RBCs seen
ascorbic acid interference = false negative
WBC in urine
can be seen in urine normally
–> less than 8 per hpf
WBC casts mean…
upper urinary tract infection
increased WBCs but no cast
evidence of lower urinary tract infection
leukocyturia
increased WBCs
increased WBC are indicative of
inflammatory urinary tract conditions and almost all renal diseases
epithelial cell in urine
can either mean
–> normal cell turnover
–> damage from inflammation
large number of epithelial cells indicate..
improperly collected urine
3 basic types of epithelial in urine
squamous, transitional, renal tubular
squamous cells in urine
rarely significant; usually from contaminatin
transitional cells in urine
seen in UTIs, urinary prodcedures, and carcinoma
renal tubular cells in urine
seen in acute ishemic or toxic renal tubular disease from heavy metals or drug
where are casts formed
in distal and collecting tubules
types of cast
hyaline, waxy, WBC, RBC, renal tubular cell, mixed cell, granular, fatty, bacterial
crystals in urine
formed in vivo and can cause tubular damage
factors influencing crystal formation
concentration of urine solute, urine pH, slow flow of urine through tubules
types of crystals
amorphous urates, calcium oxalate, (basically things that end in urate or phosphate)
