LAB - Urinalysis Module Flashcards
urine sample types
- random
- first morning
- 24 hour
- midstream
- catheterized
- suprapubic
when should urine specimens be processed?
within 2 hours of collection
- if not possible = store at 2 -8 C; protected from light
first-morning urine
- most concentrated
- ideal specimen for routine screening
- purpose: routine, pregnancy, orthostatic protein
24 hr/timed specimen
- some solutes measured in urine exhibit diurnal variation
- carefully timing these collections allows for accurate quantitative measurement of changes
- purpose = quantitative tests
catheterized urine sample
- tube passed through urethra and into the bladder to collect
- this urine is sterile
- purpose = bacterial cultures
midstream clean catch
- the genital area is cleaned before patient voids a small amount of urine to the toilet; then into container
- reduces sample contamination with epithelial cells and skin flora
- purpose = routine, bacterial cultures
suprapubic urine specimen
- needle inserted through abdomen into bladder to collect urine
- sterile
- purpose = bacterial culture, cytology
overview of urinalysis
physical
chemical
microscopic
physical examination of urine
- color
- clarity
- odor
- specific gravity
chemical examination of urine
- leukocyte esterase
- nitrites
- urobilinogen
- protein
- pH
- blood
- ketones
- bilirubin
- glucose
microscopic examination of urine
to evaluate microscopic elements present in urine sediment under specific circumstances
- casts
- cells
- crystals
- microorganisms
urine colour can be affected by:
- concentration (hydration)
- excreted metabolites
- medications
- chemicals
- cellular content
when is urine amber in colour?
- bilirubin (pathological)
- dehydration (non-path)
when is urine pink/red?
- RBCs (cloudy), hemoglobin (clear), myoglobin, porphyrins (pathological)
- beets, methyldopa (non-pathological)
when is urine orange?
- bilirubin (pathological)
- carrots, riboflavin, rhubarb (non-path)
when is urine brown/black?
- bilirubin, melanin, methemoglobin (path)
- iron compounds, levodopa, quinine (non-path)
when is urine red/brown?
porphobilin
when is urine blue/green?
- biliverdin, Pseudomonas (pathological)
- methylene blue (non-path)
cloudiness of urine can be caused by
precipitating amorphous substances
gradine urine clarity
- look from top and side of sample
- ensure it is adequately mixed before examination
dipstick urinalysis
- routine
- uses reagent strips
- strips composed of absorbent chemical pads attached to plastic strip
- colorimetric or enzymatic rxn occurs when pad comes into contact with urine
- after specific time = colour compared to a chart
= semiquantitative measure
a positive ___ ____, ____, _____ or _____ dipstick requires microscopic analysis
- leukocyte esterase
- nitrite
- protein
- blood
dipstick urinalysis - nitrite
- screening for UTIs (bacteriuria)
- cystitis, pyelonephritis
- Enterobacteriaceae produce reductase, reducing nitrate to nitrite
- Greiss reaction
> any shade of pink is pos
> bacteria must have sufficient contact tie with nitrate to produce nitrite (4 hrs)
Greiss reaction
- nitrite urinalysis (dipstick)
- acidic pH, nitrate reacts w aromatic amine to form a diazonium salt
- salt reacts with tetrahydro benzoquinoline to produce pink azo dye