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Final Practical
Physical and Chemical Examination of Urine
47
Science
Graduate
04/07/2013

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Term
Determine the specific gravity of urine using a refractometer
Definition
To determine the specific gravity using a refractometer you drop two drops of urine onto the test area of the refractometer, and then let it run through the window. You look through the lens and read off the number
Term
Determine the specific gravity of urine using a reagent test strip
Definition
To determine the specific gravity using the reagent test strip you drop urine onto the test strip and wait 60 seconds. Then you take the reading based on which color the pad is closet to.
Term
physical characteristics of urine specimens regarding color
Definition
Color is assed against a white background, urine color can be: Colorless, pale yellow, dark yellow, amber, orange, yellow-green, yellow-brown, green, blue-green, pink, red, brown or black.
Term
physical characteristics of urine specimens regarding clarity
Definition
Clarity is assed against a white background with writing on it, urine clarity can be: clear, hazy, cloudy, turbid or milky.
Term
Chemistries involved in Specific gravity chemical screening
Definition
based on a change in pKa of electrolytes placed on the reagent pad in relation to the ionic concentration of the urine. The greater the concentration of ions in the specimen, the more acid groups dissociate from the reagent, releasing hydrogen ions which leads to a more acid pH which is indicated by the bromothymol blue on the reagent pad.
Term
Chemistries involved in pH chemical screening
Definition
multi-indicator system, test pad contains the indicators methyl red, cresol red, and bromothymol blue
Term
Chemistries involved in Leukocytes chemical screening
Definition
detected by the action of esterase in granulocytic leukocytes, which catalyze the hydrolysis of an indoxylcarbonic acid ester to indoxyl which reacts with diazonium salt to produce a purple color
Term
Chemistries involved in Nitrite chemical screening
Definition
indirectly detects bacteria the reduce nitrate to nitrite. Nitrite reacts with an aromatic amine to give diazonium salt, which when coupled with another compound yields a red-violet azo dye.
Term
Chemistries involved in Protein chemical screening
Definition
- tetra-bromophenol blue based on the principle of the protein error of indicators, the presence of proteins changes the color of the indicator without changing the pH
Term
Chemistries involved in Glucose chemical screening
Definition
based on the enzymatic glucose oxidase/peroxidase method. Glucose oxidize catalyzes the formation of gluconinc acid and hydrogen peroxide from the oxidation of glucose. Peroxidase catalyzes the reaction of hydrogen peroxide with chromogen to form a green dye
Term
Chemistries involved in Ketones chemical screening
Definition
legal’s test, sodium nitroprusside and glycine react with acetoacetate and acetone in an alkaline medium to form a violet dye complex
Term
Chemistries involved in Urobilirubin chemical screening
Definition
coupled with 4-methoxybenzene-diazonium tetrafluoroborate in an acid medium to form a red azo dye
Term
Chemistries involved in Bilirubin chemical screening
Definition
diazo coupling reaction of a diazonium salt with bilirubin in an acid medium. Color in influences by urine pigment
Term
Chemistries involved in Blood chemical screening
Definition
strong pseudoperoxidase action of erythrocytes and hemoglobin. Hemoglobin and myoglobin catalyze the oxidation of the indicators by the organic peroxide in the reagent pad. Intact erythrocytes hemolyze on the test paper and liberate hemoglobin which produces a green dot
Term
Clinitest
Definition
uses the copper reduction method with Benedict’s solution, reducing substances in urine will reduce cupric sulfate to cuprous oxide in the presence of alkali and heat
Term
Acetest
Definition
Acetoacetate (and acetone) + sodium nitroprusside + glycine --> purple color in an alkaline environment maintained by buffers
Term
Ictotest
Definition
Mat causes bilirubin to remain on the surface as the urine is absorbed. Blue or purple color on mat indicates positive.
Term
When is confirmatory testing required
Definition
The confirmatory tests are necessary to confirm the positives seen on the reagent strip using a different method.
Term
Why is a confirmatory test required
Definition
It can determine the results from pigmented urine, which interferes with the reagent strip. Confirmatory tests can also test for analytes not indicated on the reagent strip.
Term
An unpreserved/unrefrigerated urine specimen should be delivered to the laboratory and tested within
Definition
1 hour
Term
Refrigeration is the method of choice for urine specimen preservation because it helps to:
Definition
decrease bacterial growth
Term
Purpose of a random urine specimen
Definition
Routine screening
Term
Purpose of a 24-hour urine specimen
Definition
Quantitative chemical testing
Term
Purpose of a catheterized urine specimen
Definition
Bacterial culture
Term
Purpose of a fasting urine specimen
Definition
Diabetic screening/monitoring
Term
If a person goes on a starvation diet, which substance would most likely be found in his/her urine specimen?
Definition
Ketones
Term
A urine’s specific gravity is directly proportional to its
Definition
dissolved solids
Term
A refractometer is used to measure:
Definition
specific gravity
Term
Upon standing at room temperature, urine pH
Definition
increases
Term
Urine reagent strips should be stored in a(n):
Definition
cool dry area
Term
Prolonged sitting of urine sample _____ nitrite
Definition
increases
Term
Prolonged sitting of urine sample _____ Bilirubin
Definition
Decreases
Term
Prolonged sitting of urine sample _____ Glucose
Definition
decreases
Term
Prolonged sitting of urine sample _____ Urobilinogen
Definition
decreases
Term
The clarity of a urine sample should be determined:
Definition
following thorough mixing of the specimen.
Term
The principle behind the reagent strip glucose test is the:
Definition
glucose oxidase reaction
Term
The principle behind the Clinitest is the:
Definition
copper reduction method.
Term
Which ketone group does not react with Acetest Tablets?
Definition
The Acetest tablets will not detect betahyroxybutyric acid.
Term
Which sugars other than glucose will react with Clinitest tablets?
Definition
The clinitest tablets detect glucose, galatose, lactose, fructose, maltose, and pentoses.
Term
specific gravity
Definition
density compared to the density of distilled water
Term
High specific gravity means
Definition
larger number and size of dissolved particles
Term
Reference range of specific gravity
Definition
1.001-1.035
Term
how does a refractometer determine specific gravity
Definition
using refractive index, comparison of velocity of light in air versus its velocity in solution, angle passing through prism is converted to SG value
Term
acetest tests for
Definition
ketones
Term
icotest tests for
Definition
bilirubin
Term
clinitest tests for
Definition
reducing sugars
Term
use of clinitest
Definition
screen newborns for metabolic defects
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