urine physical exam Flashcards
Types of common urine specimens
Random, first morning, midstream clean catch, catheterized, 24-hour (timed), drug screening.
first morning urine is for
confirmatory test for orthostatic proteinuria and pregnancy.
for bacterial cultures
midstream clean catch and catheterized
provide quantitative results
24 hour (timed) urine
strictly follow chain-of-custody form requirements
Drug screening
Test specimens within
2 hours of collection
_____________ specimens that cannot be tested within 2 hours
Refrigerate
increased results in unpreserved urine
pH, nitrite, bacteria
decreased results in unpreserved urine
Glucose - glycolysis,Ketones - Oxidation,Bilirubin - Oxidation to biliverdin,Urobilinogen - oxidation to urobilin.
normal urine volume
600 to 2000 mL/day
decreased urine output
oliguria, less than 400mL/day
no urine output
anuria
increased urine output at night
nocturia
increased urine output
polyuria, greater than 2500 mL/day
increased urine output to excrete excess urine glucose is seen in
Diabetes mellitus
increased urine output caused by lack or dysfunction of antidiuretic hormone (ADH) is seen in
Diabetes insipidus
polyuria results in
polydipsia
normal urine color is
yellow
Seen in refrigerated normal urine
White turbidity - urine with alkaline pH from amorphous phosphates and carbonates.Pink rabidity - urine with an acid pH from amorphous urates.
Nonpathologic turbidity
squamous epithelial cells,mucus,amorphous phosphates,carbonates, and urates,semen,feces,radiographic contrast edia,powder and creams.
Pathologic turbidity
RBCs,WBCs,yeast,urothelial and renal tubular epithelial cells,abnormal crustals,lipids (milky).
Specific gravity is a
screening test for reneal tubular reabsorption of essential elements filtered by the glomerulus
specific gravity is based on the fact that glomerular filtrate ha a specific gravity of
1.010
urine contains dissolved substances that produce density by their
size and number
principle of sp. gr. in reagent strip
based on the number of hydrogen ions released from a polyelectrolyte (pKa) is proportional to the number of ions in the urine.increased urine concentration = increased hydrogen ions released = low pHthe indicator on the strip is bromothymol bluereaction - yellow-green (acid) - green-blue (alkaline)
principle of refractometer
the concentration of dissolved particles in a solution determines the velocity and angle of light passing through a solution.the refractometer uses a prism to direct a wavelength of light through the urine, the angle of the light can be read on a scale calibrated with distilled water.
considered more representative of renal concentrating ability than specific gravity
osmolarity, because it measures only the number of particles and their size is not relevant.measurement is the number of particles into which 1gram MW of a substance dissociates.ex: Nonionizing urea (MW 60) = 1 particle, ionizing NaCl (MW 58.5) = 2 particles.reported in milliosmoles (mOsm)
Colligative properties measured in the clinical laboratory
freezing point depression and vapor pressure depression.
describe freezing point depression
one mole of nonionizing substance will lower the freezing point 1.86 oC.Volatile substances such as alcohol can interfere.
Describe vapor pressure depression
Actual measurement is the dew point (temperature at which vapor condenses to a liquid) of the urine sample.Uses microsamples on filter paper discs. Care must be taken to avoid evaporation.No interference from volatile substances.
Normal serum osmolarity
275 t0 300 mOsm
urine osmolality is influenced by
fluid intake
random serum-to-urine osmolarity ratio is
1:1
controlled fluid intake should reach
1:3
Osmolarity is used to
determine ADH production or tubular response to ADH for diabetes insipidus.uses harmonic oscillation density?
automated instrumentation principle on osmolarity
it passes a sound wave through the urine and records the change in frequency of the sound wave, which is proportional to the urine density
