BRUNZEL Chapter 5 Flashcards
The study of______ is the oldest clinical laboratory test still performed.
Historically, only the physical characteristics of urine were evaluated-(4).
The latter characteristic-_____—has not been performed for centuries because of chemical methods that can be used to assess the “sweetness” of urine.
urine
color, clarity, odor, and taste
taste
The______ characteristics of urine continue to play an important part in a routine urinalysis.
The presence of disease processes and abnormal urine components can be evident during the initial _____ examination of urine.
physical
________, which is normally various shades of yellow, can range from colorless to amber to orange, red, green, blue, brown, or even black.
These variations can indicate the presence of a (3).
However, color variations can simply result from excessive____ or ____.
It is important to note that a change in urine color is often the initial or only reason why an individual seeks medical attention.
Urine color
disease process
metabolic abnormality
ingested food or drug
physical activity or stress
The characteristic yellow color of normal urine is principally due to the pigment_______!
It is a product of_______ metabolism, it is a_____-soluble pigment that is present in_____ and excreted in urine.
urochrome
endogenous metabolism
lipid
plasma
Patients in_________, with decreased excretion of urochrome, may exhibit a characteristic yellow pigmentation of their skin caused by deposition of urochrome in their subcutaneous fat.
chronic renal failure
Because______ production and excretion are constant, the intensity of the color of urine provides a crude indicator of urine concentration and the hydration state of the body.
urochrome
Urochrome, similar to other lipid-soluble pigments, darkens on exposure to_____.
This characteristic darkening is often observed in urine specimens that are______.
light
improperly stored
Small amounts of urobilin (______ pigment) and uroerythrin (a______ pigment) also contribute to urine color.
orange-brown
pink
_______ and _____ are normal urine constituents;
Urobilin and uroerythin
________is most evident when it deposits on urate crystals, producing a precipitate often described as brick dust.
uroerythin
Terms such as straw and beer brown should be replaced with_____ and ____
The term____ should be avoided.
Although bloody is descriptive, it is not a color; _____ or ____would be more appropriate.
light yellow and amber.
bloody
red or pink
An abnormal urine, that is, one that reflects a pathologic process, may not have an abnormal color, whereas a normally colored urine may contain significant pathologic elements.
For example, a normal yellow or colorless urine can actually contain large amounts of_____ or _____
In contrast, a red urine, often an indicator of the presence of blood, can result from the ingestion of_____ by genetically disposed individuals.
Nevertheless, urine color is valuable in the preliminary assessment of a urine specimen.
glucose or porphobilinogen.
beets
Many substances are capable of modifying the normal color of urine.
The same substance can impart a different color to urine depending on (3)
(1) the amount of the substance present;
(2) the urine pH;
(3) the structural form of the substance, which can change over time.
In fresh______ urine, red blood cells can be present despite a typical yellow-colored urine, or the urine color may appear pink or red.
The color of the urine varies with the quantity of red blood cells present.
acidic
As red blood cells disintegrate,_____ is released and oxidizes to____, which causes the urine color to become_____ or ______.
hemoglobin> methemoglobin
brown or even black
Alkaline urine with red blood cells present is often______ in color.
In such specimens, disintegration of cellular components is enhanced by the alkaline pH, and hemoglobin oxidation is promoted.
red-brown
When glomerular or tubular damage of nephrons occurs, blood enters the urinary tract and the hemoglobin becomes oxidized before it collects in the bladder.
In this case the urine appears______ rather than the typical red color that is associated with the presence of blood.
brownish
A fresh brown urine can indicate the presence of (3).
blood, hemoglobin, or myoglobin
Distinguishing among the substances is difficult, particularly between hemoglobin and myoglobin, because all three produce a positive chemical test for_____.
Red blood cells are confirmed by_______, whereas the discrimination between hemoglobin and myoglobin requires additional urine chemical testing and possibly an evaluation of the_______.
blood
microscopic examination
blood plasma
______is another substance that can contribute to urine color.
It is a byproduct of hemoglobin catabolism and has a characteristic yellow color.
Bilirubin
When present in sufficient amounts in urine or plasma, bilirubin imparts a distinctive_____ coloration.
However, upon standing or improper storage, bilirubin oxidizes to_______, causing the urine to take on a_____ hue.
amber
biliverdin> greenish
Bilirubin is also susceptible to_____ by artificial light or sunlight; therefore, specimens must be stored properly to avoid degradation of this component.
This photosensitivity is temperature dependent; optimal specimen stability is obtained by storing the specimens at______ in the ______
photooxidation
low temperatures in the dark.
Some substances are colorless and normally do not contribute to urine color.
However, upon standing or improper storage, they convert to colored compounds.
________, a normal constituent in urine, is colorless, whereas its oxidation product_____ is orange-brown.
Urobilinogen> urobilin
Urobilinogen, a normal constituent in urine, is_______, whereas its oxidation product urobilin is______.
colorless
orange-brown
