Clinical Study Questions Flashcards
What are the three ketone bodies?
acetone, acetoacetic acid, beta-hydroxybutyric acid
What does the presence of ketone bodies in urine indicate?
carbohydrate metabolism is deficient, body is using fat as the major energy source
Which ketone body exists in the highest concentration?
beta-hydroxybutyric acid
Which ketone body are most urinalysis strip tests most sensitive to?
acetoacetic acid
What is the principle of the reaction for ketone bodies with Multistix testing?
sodium nitroprusside, in the presence of acetoacetic acid, produces a color change from buff pink (=) to purple (+) as ketone concentration increases
Are acetone and/or beta-hydroxybutyric acid detected with Multistix testing?
no
What is the pH a measure of in terms of kidney function?
measures the kidney’s ability to maintain normal hydrogen ion concentration in plasma and extracellular fluid
What is the principle of the reaction for pH with Multistix testing?
utilizes the methyl red/bromthymol blue indicator system, which provides pH readings from 5.0-8.5; test pad color changes from orange to green to blue in this pH range
What is hematuria and when would it be seen?
abnormal number of intact red cells; kidney or urinary tract disease
What is hemoglobinuria and when would it be seen?
free hemoglobin in the urine; any condition resulting in intravascular hemolysis
What is myoglobinuria and when would it be seen?
myoglobin (heme-containing protein) in the urine; rhabdomyolysis (muscle destruction)
What is the principle of the reaction for occult blood in Multistix testing?
based on the peroxidase-like activity of hemoglobin, which catalyzes the reaction of diisopropylbenzene dihydroperoxide and uses 3,3’,5,5’-tetramethylbenzidine; blood is detected as intact red cells or as free hemoglobin; liberation of oxygen from peroxide through heme causes a benzidine compound to oxidize to a colored product ranging from orange to green to dark blue
How is protein measured with Multistix testing?
protein error of indicators; utilizes tetrabromophenol blue reagent buffered at a pH of 3; the point of color change is different in the presence or absence of certain proteins, ranging from yellow (=) through yellow-green, green, and blue-green
What must one keep in mind when testing for protein with Multistix in regards to sensitivity?
test pad is more sensitive to albumin than globulins (gammaglobulins, Bence-Jones proteins, hemoglobin, mucoprotein), and a negative result does not necessarily rule out the presence of the other proteins
What reaction can be caused by buffered alkaline urine in regards to protein Multistix testing?
may produce false positives
What is the difference between specific gravity and osmolality?
specific gravity measures the ratio of the density of a substance to the density of a reference substance; osmolality measures the concentration of a substance contained within a reference substance
Between specific gravity and osmolality, which is more accurate and why?
osmolality; it is not affected by large or heavy particles, whereas specific gravity is
Which protein in urine coagulates on heating to 45-60*C and re-dissolves on further heating to the boiling point?
Bence-Jones protein
What two structures may be confused with white cells in a urine specimen, and how would they be differentiated?
red cells (smaller, bi-concave, can be lysed with 2% acetic acid); collecting duct cells (large and dense nuclei, polygonal shape)
What two structures may be confused with red cells in a urine specimen, and how would they be differentiated?
bubbles (variation in size, highly refractile); yeast (variation in size, tends to be more spherical/ovoid rather than bi-concave, exhibits budding, will not lyse in acetic acid)
What is the reaction of the Multistix reaction for glucose?
double sequential enzyme reaction: glucose + O2 –glucose oxidase–> gluconic acid + H2O2 –> H2O2 + chromagen –peroxidase–> oxidized chromagen + H2O
Under what conditions would you see a negative dipstick and a positive Clinitest when testing for glucose?
non-glucose reducing substance (typically galactose)
What are oval fat bodies?
renal tubular epithelial cells containing fat
What do oval fat bodies exhibit under polarized microscopy?
Maltese cross formation
Where are casts formed?
distal and collecting tubules of the kidneys
What conditions bring about cast formation?
can appear normally (hyaline casts), glomerulonephritis, acute interstitial nephritis, pyelonephritis, chronic or acute renal disease, athletic pseudonephritis
What do casts signify clinically?
number of casts reflects the extent of tubular involvement and severity of disease; type and number together can indicate a specific disease state
Can the width of a cast be an indication of the severity of renal disease? Explain.
yes; broad casts (called renal failure casts) indicate cast formation in dilated convoluted tubules or in the collecting ducts; because one collecting duct may serve several nephrons, cast formation within them indicates significant urinary stasis due to either obstruction or disease
What are hyaline casts composed of and when can they appear?
Tamm-Horsefall protein matrices; following strenuous exercise and stress
What constitutes a cellular cast?
protein matrix filled with degenerating cells
When can bacterial casts appear?
pyelonephritis and kidney infections
When can red cell casts appear?
glomerulonephritis and strenuous exercise
What are fatty casts and what are they associated with?
protein matrix containing fat globules; nephrotic syndrome
What are waxy casts and how do they appear?
final breakdown product of a cellular cast; sharp, refractile outline with irregular, broken-off ends
What kind of casts can appear in renal tubular damage?
renal tubular epithelial cell casts
What is nephrotic syndrome?
caused by damage to the kidneys resulting in the release of too much protein into the urine
What results would be expected in a urinalysis on a patient with nephrotic syndrome?
large amounts of protein, fatty casts
What is the synonym for nephrotic syndrome?
nephrosis
What is the source of bleeding if urine contains red cells but minimal protein?
kidneys (glomerulonephritis)
What does the creatinine clearance test measure?
glomerular filtration rate
In what two types of jaundice will bilirubin be found in the urine?
hepatic, obstructive
What is the principle of the reaction for bilirubin with Multistix testing?
bilirubin reacts with diazonium salt (2,4-dichloroaniline) to form a tan color
What three urine constituents are detected by the SSA protein procedure but not by the protein portion of Multistix?
albumin, Bence-Jones protein, and immunoglobulin light chains
In what two types of jaundice will increased urobilinogen be found in the urine?
hepatic, hemolytic
What is the principle of the reaction for urobilinogen with Multistix testing?
urobilinogen will react with p-dimethylaminobenzaldehyde in an acid medium to produce a pink-red color
In what two conditions will urobilinogen be decreased in the urine, and why?
obstructive jaundice - bile containing direct bilirubin cannot enter the intestines, where it becomes urobilinogen; chronic liver disease - indirect bilirubin cannot be further processed by the liver, meaning there is little direct bilirubin available for conversion to urobilinogen
What is a glitter cell?
swollen white cells whose cytoplasmic granules exhibit Brownian movement; associated with pyelonephritis and low specific gravity
What are kidney stones?
solid material formed in the kidneys from minerals present in the urine; also called renal calculi or nephroliths
What is the most common type of kidney stone?
calcium compounds, such as calcium oxalate or calcium phosphate
What is the spot plate method of calculi analysis?
a drop of chemical reagent is added to the unidentified calculi; if the compound being tested for is present, observable changes will take place
What effect does radiographic dye have on specific gravity?
increases it
