1. Intro to Urinalysis Flashcards
“Uroscopy” book
Hippocrates 5th century BC
first urine color charts
1140 CE
discovery of albuminuria
1694
urinalysis introduced as part of routine patient exam
1827
body converts —— mL of filtered plasma to ——- mL of urine each day
170,000
1,200
primary components in normal urine (9)
- urea
- creatinine
- uric acid
- chloride
- sodium
- potassium
- phosphate
- ammonium
- calcium
define urea
primary organic component
product of amino acid metabolism
1/2 the total dissolved solids
define creatinine
product of creatine metabolism in muscles
ID a fluid as urine
urea + creatinine
define uric acid
product of nucleic acid breakdown
primary inorganic component
chloride
formed elements found in urine
cells
casts
crystals
mucus
bacteria
factors that influence urine volume (4)
- Fluid intake
- Fluid loss from nonrenal sources
- Variations in the secretion of ADH
- Need to excrete increased amounts of dissolved solids, such as glucose or salts
average urine output range
normal urine output range
1200-1500 mL
800-2000 mL
oliguria
decrease in urine output
dehydration
< 400 mL/day in adults
cessation of urine flow
anuria
increase in daily urine volume
polyuria
> 2500 mL/day in adults
polyuria can indicate…
DM
DI
increased body glucose concentration
DM
why does DM lead to polyuria?
increased amounts of water are needed to remove excess glucose from the body
what is different about the urine of DM patients and DI patients?
specific gravity
DM: increased
DI: decreased
decrease in production or function of ADH
DI
3 general types of urine containers
cups
individual collection devices
24-hour urine jugs
cup capacity
50 mL
individual urine tube capacity
10-12 mL
24 hour jug capacity
3000 mL
All specimens should be labelled with… (7)
- Patient’s Name
- Medical Record Number (MRN)
- DOB/age
- Patient Location
- Date & Time of Collection
- Collector’s Initials
- Tests to be run
must accompany specimens delivered to the lab - must match info on label
requisition form
types of urine deterioration over time (5)
- microbial
- oxidative
- photolytic
- thermal
- autolytic
which metabolic processes to the bacteria continue to undergo over time?
- Decompose ketone bodies
- Ferment glucose
- Produce NH3 (ammonia) from the breakdown of urea
- Reduces nitrates to nitrites
- Alters pH (NH3 production changes the pH to alkaline)
example of oxidative deterioration
urine color can change from brown to green due to bilirubin being oxidized to biliverdin
analyte that is unstable when exposed to light, collected in a brown bottle
porphyrins
examples of autolytic deterioration
RBCs and WBCs lyse
casts deteriorate (↑ pH)
Change to unpreserved urine after 2 hours
color
darkened
oxidation/reduction of metabolites
Change to unpreserved urine after 2 hours
clarity
decreased
bacterial growth
precipitation of amorphous material
Change to unpreserved urine after 2 hours
odor
increased
bacterial multiplication, breakdown of urea to ammonia
Change to unpreserved urine after 2 hours
pH
increased
breakdown of urea to ammonia
loss of CO2
Change to unpreserved urine after 2 hours
glucose
decreased
glycolysis
bacterial use
Change to unpreserved urine after 2 hours
ketones
decreased
volatilization
bacterial metabolism
Change to unpreserved urine after 2 hours
bilirubin
decreased
photooxidation to biliverdin
Change to unpreserved urine after 2 hours
urobilinogen
decreased
oxidation to urobilin
Change to unpreserved urine after 2 hours
nitrite
increased
bacteria
Change to unpreserved urine after 2 hours
RBC/WBC/casts
decreased
deterioration in dilute alkaline urine
Change to unpreserved urine after 2 hours
bacteria
increased
Change to unpreserved urine after 2 hours
trichomonas
decreased
death
loss of motility
urine refrigeration temperature
2°-8°
the ideal preservative
- bactericidal
- inhibit urease
- preserve formed elements
- not interfere with chemical tests
refrigeration
disadvantage
precipitates amorphous phosphates and urates
boric acid
advantage
disadvantage
keeps pH at —-, used for urine culture transport
prevents bacterial growth/metabolism
interferes with drug and hormone analyses
6.0
formalin
advantage
disadvantage
preserves cells and casts
interferes with chemical tests (reducing agent)
sodium fluoride
advantage
disadvantage
good preservative for drug analyses
inhibits reagent test strips for glucose, blood, WBCs
C&S tube
function
stability
limitations
culture; prevents bacterial growth/metabolism
stable at RT for 48 hr
do not use if below fill line
yellow UA plus tube
function
limitations
preservative
used on automated instruments
refrigerate within 2 hours
no preservative
tiger tops
function
stability
limitations
preservatives
urine-instrument compatible
stable for 72 hr at RT
not used for culture
must be filled to minimum fill line
sodium propionate, ethyl paraben, chlorhexidine
most commonly received specimen
random specimen
now-uncommon specimen that took the 2nd void of the day
fasting urine
ideal urine specimen
first morning
best specimen for pregnancy testing, detection of chemicals and formed elements, and for evaluation orthostatic proteinuria
first morning
used for quantitative measurement of analytes
24 hour urine
diurnal variation
Some analytes are excreted in varying concentrations during a 24-hour period
catecholamines, 17-hydroxysteroids, and electrolytes
lowest concentration is in the early morning and the highest concentration occurs in the afternoon
instructions for start and end times for 24 hour collection
Completely void the bladder of urine into the toilet and record this date and time as the START of the collection.
Even if there is not a big urge to urinate at the exact END time, it is best to try and add it to the collection. The final collection should be recorded as the END date and time.
specimen of choice for cytologic exam
suprapubic aspiration
process that provides documentation of proper collection and identification from the time of collection to the receipt of lab results
chain of custody
drug screen
volume collected
30-45 mL
drug screen
temperature taken within…
4 minutes
drug screen
temp should fall between….
32.5° - 37.7°
