AUBF BOOK (Finals) Flashcards
Reagent strips currently provide a simple, rapid means
for performing medically significant chemical analysis of
urine including
pH
protein
glucose
ketones
blood,
bilirubin
urobilinogen
nitrite
leukocytes
specific gravity
Two major brands for reagent strips
Multistix and Chemstrip
Reagent strips should be read between
60 to 120 secs
Strips are dependent on ____
temperature
Manufacturers recommend that reagent strips be stored at
room temperature below
30 deg C
QC of reagent strips
Reagent strips must be checked with both positive and negative
controls a minimum of once every
24 hours
can cause a highly dark yellow colored urine
Phenazopyridine
CARE OF REAGENT STRIPS
Store with desiccant in an opaque, tightly closed container
Store below 30°C; do not freeze.
Do not expose to volatile fumes.
Do not use past the expiration date.
Do not use if chemical pads become discolored
Remove strips immediately prior to use
A healthy individual usually produces a first morning specimen with a slightly acidic pH of
5.0 to 6.0
An alkaline pH is found following
meals
The pH of normal random samples can range from
4.5 to 8.0
Persons with high protein and high meat pH:
more acidic urine
Vegetarians urine pH
more alkaline
Cranberries produces an
acidic urine
Medications such as methenamine, mandelamine, or monurol are metabolites to produce
acidic urine
The pH of freshly excreted urine does not reach above
8.5
A pH above 8.5 is associated with an
improperly preserved specimen
Amorphous urate is seen in pH
Acidic
Amorphous phosphate is seen in pH
alkali
Renal alkali seen in urine indicates
kidney stones
The Multistix and Chemstrip brands of reagent strips measure urine pH in 0.5- or 1-unit increments between pH 5 and 9 color change
5 orange > yellow > 9 blue
produces a color change from red to yellow in the pH range 4 to 6,
Methyl red
Turns from yellow to blue in the range of 6 to 9
bromothymol blue
Most indicative of renal disease is the —- determination
Protein
Often associated with early renal disease.
Proteinuria
Normal urine contains very little protein: usually, less than ___ is excreted
10 mg/dL or 100 mg per 24 hours
Consist of low molecular proteins that have been filtered by the ____
glomerulus
major serum protein found in normal urine
Albumin
Much of the filtered albumin is reabsorbed by the _______.
tubules
Produced in renal epithelial tubular cells and prostatic seminal and vaginal secretions
Tamm-Horsfall protein (uromodulin)
Routinely produced in the DCT (distal convoluted tubule)
Tamm-Horsfall protein (uromodulin)
Clinical proteinuria is indicated at
30 mg/dL or greater (300 mg/L)
Normal value of proteinuria
Normal – less than 10 mg/DL
caused by conditions affecting the plasma prior to it reaching the kidney, and therefore, is not indicative of actual renal disease
Prerenal proteinuria
A proliferative disorder of the immunoglobulin producing plasma cells, the serum contains markedly elevated levels of monoclonal immunoglobulin light chains
Bence Jonce Protein (Multiple Myeloma)
Renal proteinuria associated with true renal disease may be the result of either
glomerular or tubular damage
toxic substances, and the immune complexes found in lupus erythematosus and streptococcal glomerulonephritis
Amyloid material
Proteinuria that occurs during the latter months of pregnancy may indicate a
pre-eclamptic state
Indication of strenuous exercises, high fever, dehydration, exposure to cold, protein shakes with amino acids
Benign proteinuria
Indicates the presence of an abnormal urinary excretion of albumin, signifying endothelial dysfunction and an increased risk for cardiovascular morbidity and mortality
Microalbuminuria
Occurs following periods spent in a vertical posture and disappears when a horizontal position is assumed.
Orthostatic (Postural) Proteinuria
Causes – exposure to toxic substances and heavy metals
Tubular proteinuria
The amount of protein that appears in the urine following glomerular damage ranges from slightly above normal to
4g/day
Bacterial and fungal infections and inflammations produce exudates containing protein from the interstitial fluid
Post Renal Proteinuria
tetrabromophenol blue multistix detects:
Protein
tetrachlorophenol acid buffer
protein
Cold precipitation test that reacts equally with all forms of protein.
All precipitation tests must be performed on centrifuged specimens to remove any extraneous contamination.
Sulfosalicylic Acid Precipitation Test
Micral-Test reagent strips contain a ______
. Strips are dipped into the urine up to a level marked on the strip and held for 5 seconds. Albumin in the urine binds to the antibody.
gold-labeled antihuman albumin antibody-enzyme conjugate
Color produced in testing microalbuminuria ranging from:
white to red
Result range for testing microalbuminuria
0-10 dL
REAGENT STRIP REACTIONS:
Albumin reagent strips use the dye
bis-3,4,5,6-
tetrabromosulphonphthalein (DIDNTB)
Color result of albumin in reagent strips:
pale green to aqua blue
REAGENT STRIP REACTIONS:
Creatinine in the urine combines with the copper sulfate to form
copper creatinine pseudoperoxidase
Result in creatinine is reported as
10, 50, 100, 200, 300 mg/dL, or 0.9, 4.4, 8.8, 17.7, or 26.5 mmol/L of creatinine
Falsely elevated results in creatinine can be caused by
visibly blood urine
presence of gastric acid reducing medication cimetidine
normal creatinine concentrations:
10 to 300 mg/dL
Abnormal results for the A:C ratio are
30 to 300 mg/g or 3.4 to 33.9 mg/mmol
Prerenal protein clinical significance:
Intravascular hemolysis
Muscle injury
Acute phase reactants
Multiple myeloma
Clinical significance of tubular disorders
Fanconi syndrome
Toxic agents/heavy metals
Severe viral infections
Renal protein clinical significance
Glomerular disorders
Immune complex
disorders
Amyloidosis
Toxic agents
Diabetic nephropathy
Strenuous exercise
Dehydration
Hypertension
Pre-eclampsia
Orthostatic or postural proteinuria
Post renal protein clinical significance
Lower urinary tract infections/
inflammation
Injury/trauma
Menstrual contamination
Prostatic fluid/spermatozoa
Vaginal secretions
Clinical Significance of
Urine Glucose: Hyperglycemia associated
Diabetes mellitus
Pancreatitis
Pancreatic cancer
Acromegaly
Cushing syndrome
Hyperthyroidism
Pheochromocytoma
Central nervous system damage
Stress
Gestational diabetes
Clinical Significance of
Urine Glucose:
Renal Associated
Fanconi syndrome
Advanced renal
disease
Osteomalacia
Pregnancy
Renal threshold for glucose is
approximately
160 to 180 mg/dL
For purposes of diabetes monitoring, specimens are usually
tested
2 hours after meal
Occurs in the absence of hyperglycemia when the
reabsorption of glucose by the renal tubules is compromised
Glycosuria
False positive in glucose strips
Containers contaminated with peroxide or strong oxidizing detergents
False negative reaction with glucose strips:
High levels of ascorbic acid
High levels of ketones
High specific gravity
Low temperatures
improperly preserved specimens
Copper Reduction Test (Clinitest) result for glucose
negative blue (Cus04)
through green, yellow, and orange/red (Cu20)
Reagents for glucose Multistix
Glucose oxidase Peroxidase
Potassium iodide
Reagents for glucose Chemstrip
Glucose oxidase Peroxidase
Tetramethylbenzidine
Sensitivity for glucose multistix
75 to 125 mg/dL
Sensitivity for glucose chemstrip
40 mg/dL
Correlations with other tests of glucose
Ketones and protein
Three intermediate products of fat metabolism in ketones
acetone (2%), acetoacetic acid (20%), and b-hydroxybutyrate (78%)
Testing for urinary ketones is most valuable in the management and monitoring of
Insulin-dependent (type 1)
diabetes mellitus.
Reagent strip tests for ketones use the
sodium nitroprusside
(nitroferricyanide)
Falsely decreased values of ketones
improperly preserved specimens
False-positive for ketones
Phthalein dyes
Highly pigmented red urine
Levodopa
Medications containing free
sulfhydryl groups
provides sodium nitroprusside, glycine, disodium phosphate, and lactose in tablet form
Acetest Tablets
produces a cloudy
red urine
hematuria
appears as a clear red
specimen.
hemoglobinuria
Result of reagent strip in RBCs:
pseudo-peroxidase activity of hemoglobin to catalyze a reaction between the heme component of both
hemoglobin and myoglobin and the chromogen tetramethylbenzidine to produce an oxidized chromogen
green-blue color
REAGENT STRIP REACTIONS of bilirubin
Diazo reaction
Diazo reaction for bilirubin uses
Multistix: 2,4-dichloroaniline diazonium salt
Chemstrip: 2,6-dichlorobenzenediazonium salt
Reaction color for bilirubin in reagent strips
tan or pink to violet
False positive result of Bilirubin
Highly pigmented urines,
phenazopyridine
Indican (intestinal disorders)
Metabolites of Lodine
False negative result of bilirubin
Specimen exposure to light
Ascorbic acid greater than 25 mg/dL
High concentrations of nitrite
A confirmatory test for bilirubin
ICTOTEST TABLETS
Ictotest tablets contains:
p-nitrobenzenediazonium- p-toluenesulfonate
SSA
sodium carbonate
boric acid
Ictotest result in the presence of bilirubin
Blue to purple
Urobilinogen reagent in multistix
p-dimethylaminobenzaldehyde (Erlich’s reagent)
Ehrlich’s aldehyde reaction is used in
Urobilinogen
Urobilinogen produces colors ranging from
light to dark pink
False-negative results of urobilinogen
improperly preserved
formalin is used as a preservative
Greiss reaction is seen in
Nitrite
Color result of nitrite
Pink color
False-negative nitrite
Nonreductase-containing bacteria
Insufficient contact time between
bacteria and urinary nitrate
Lack of urinary nitrate
Large quantities of bacteria convert-
ing nitrite to nitrogen
Presence of antibiotics
High concentrations of ascorbic acid
High specific gravity
Fase positive of nitrite
Improperly preserved specimens
Highly pigmented urine
Reaction of Leukocyte esterase in reagent strip
purple
Reading time for Leukocyte esterase
2 mins
Reagents for Leukocyte esterase
Multistix: Derivatized pyrrole amino acid ester, Diazonium salt
Chemstrip: Indoxylcarbonic acid ester, Diazonium salt
False positive reaction of Leukocyte esterase
Strong oxidizing agents, formalin, highly pigmented urine, nitrofurantoin
False negative reaction of Leukocyte esterase
High concentrations of protein, glucose, oxalic acid, ascorbic acid, gentamicin, cephalosporins, tetracyclines, inaccurate timing
Principle of Specific gravity
pKa Change in Polyelectrolyte
Reagents for SG
Multistix: Poly (methyl vinyl ether/maleic anhydride) bromthymol blue
Chemstrip: Ethylene glycol diaminoethyl ether tetraacetic acid, bromthymol blue
False positive result in specific gravity
High concentrations of protein
Fase negative result of specific gravity
Highly alkaline urine (>6.5)
Correlations of pH
Nitrite, Leukocytes
Correlatioin of glucose
Ketones, Proteins
Correlation of protein
Blood, Nitrite, Leukocytes
correlation of ketones
glucose
Correlation of Blood
Proteins
Correlation of Bilirubin
Urobilinogen
Correlation of Urobilinogen
Bilirubin
Nitrite correlation
Protein, Leukocytes
Correlation of leukocyte esterase
Protein, Nitrite
