Chemical Analysis of Urine Flashcards
pH of urine is reflection of:
ability of kidneys to maintain normal hydrogen ion concentration in plasma and extracellular fluid
urine pH has 2 main objectives
diagnostic
therapeutic
pH range of urine
5.0-8.5
vegetable diet results in urine pH of
higher than 6
diet high in protein results in urine pH that is more
acidic
factors resulting in persistent acidic diet
dehydration diarrhea fever diabetes ketoacidosis gout pulmonary emphysema high protein diet or cranberries renal tubular acidosis acidifying drugs
factors resulting in persistent alkalinity
acute and chronic renal failure UTI bacterial continuation of urine sample alkaline drugs diuretics
small amounts of low-molecular weight protein could be found in urine – from _______ tract
genito-urinary tract
mucoprotein Tamm-Horsfall (T-H) is secreted by _______ and is NOT derived from ______
renal tubules
blood plasma
less than ______ mg/24 hour of T-H protein is excreted and is the matrix for ______
150 mg/24 hour period
formation of calculi or casts
testing for protein in urine is based off of principle called _________, which is the ability of protein to alter the color of some acid-base indicators without altering pH
Protein Error of pH indicators
in a solution void of protein, pH =
3 (yellow)
in the presence of protein, color on dipstick changes to ____, then ____ based on concentration; this method is more sensitive to ______ than _____
green then blue
albumin than globulin
false positive of protein in urine may come from:
highly buffered alkaline urine prolonged exposure to sample container cleaning compounds some skin cleaners blood in urine
false negative of protein in urine may come from:
diluted urines
elevated amounts of protein other than albumin
factors that could contribute to temporary proteinuria
strenuous exercise postural proteinuria dehydration exposure to heat or cold fever emotional stress pregnancy
(3) diseases causing consistent proteinuria
glomerulonephritis
pyelonephritis
malignant HTN
100% of glucose is reabsorbed in _______; usually not present in urine unless _______ mg/dl in blood
proximal tubules
160-180 mg/dl
urine glucose false positive may come from: (3)
oxidizing cleaning agents for urine containers (hydrogen peroxide)
patients taking Levodopa (parkinson’s disease)
high levels of ketones in urine
urine glucose false negative may come from (4)
cool urine
urine with high specific gravity due to uricosuria
alkaline urine due to bacterial contamination of old urine
ascorbic acid (vit C) in high doses can inhibit enzymatic reaction
when glucose concentration is present in urine 2 hours after eating sweet foods
transient glucosuria
glucosuria depends on:
blood glucose levels
glomerular filtration rates
tubular reabsorption
glucosuria is seen in (2) diseases
diabetes mellitus
congenital forms of glucosuria
PERSISTENT glucosuria develops in: (6)
diabetes mellitus CNS problem kidney problems endocrine problems liver disorders pharmaceutical agents
second method for measurement of glucose in urine; detects ALL _____ sugars except _____
Clinitest aka Benedict’s Test
reducing sugars except glucose
Clinitest (benedict’s test) is predominately used for diagnosing ______
galactosemia
false positives for Clinitest (4)
ascorbic acid
cephalosphorins
probenecid (treating gout and hyperuricemia)
urinary preservatives (formalin and formaldehyde)
false negatives for Clinitest (1)
technique errors
urine reducing sugar test is screening for GENETIC disorders of _______ metabolism; routinely performed in ______; early detection of ______
carbohydrate
newborns
galactosemia
ketones are normally produced by ______, as part of fatty acid metabolism
liver
if body cannot get enough _____ for energy, it will switch to using it’s body fats –> increase _____ production making them detectable in urine and blood
glucose
ketone
ketone bodies that commonly appear in urine when fats burned for energy (3)
acetoacetic acid
beta-hydroxybutyric acid
acetone
dipsticks test determine ______ for protein, but never ____ for protein
acetoacetic acid (sometimes acetone) never beta-hydroxybutyric acid
false positive for urine ketone with atypical color (6)
highly pigmented urine combination of high specific gravity and low pH dehydration phenylketones some meds ascorbic acid
(2) reasons for false negatives for urine ketons
delay in testing
loss of reagent activity
ketone bodies can signify: (9)
diabetes mellitus malabsorption syndrome exposure to cold fasting fever insufficient carb intake malnutrition strenuous exercise vomiting
positive dipstick for blood in urine
hematuria
hemoglobinuria
myoglobinuria
blood in urine may be released from any organ of GENITO-URINARY tract
hematuria
blood in urine due to intravascular distraction of RBC - Glomerular filtrate
hemoglobinuria
blood in urine due to muscle damage - Glomerular filtrate
myoglobinuria
(3) reasons for false positive for blood in urine
cleanser- oxidizing contaminant
bacterial peroxidase
menstrual blood
(6) reasons for false negative for blood in urine
technique errors inadequate mixing of urine sample formalin preservative high conc. of ascorbic acid (vit C) high specific gravity nitrates proteins
Hematuria is the presence of blood or intact ____ in the urine. A urine that is highly _____ or has a very low ______ can cause the red cells to lyse, thus releasing their hemoglobin into the urine.
RBCs
alkaline
specific gravity (1.007)
if RBCs lyse in urine, the microscopic exam may show empty RBC membranes called:
ghost cells
transient hematuria may result from:
strenuous exercise
menstrual contamination
persistent urine blood (hematuria) may develop with (2)
renal diseases (glomerular, tubular, interstitial, vascular) trauma to kidneys
persistent hematuria may be present in patients with
urolithiasis (kidney stones) UTI urinary tract tumor bleeding disorders related to anticoagulant therapy prostatic cancer gynecological disorders ebola
free hemoglobin(hemoglobinuria) may be found in urine if
(intravascular hemolysis) incompatible blood transfusion hemolytic anemias immunohemolytic anemias burns electric shock
myoglobinuria may be due to: (6)
rhabdomyolysis electric shock myocardial infarction heroin abuse alcoholism after strenuous activity
___ & ____ will both produce positive reagent strip blood results because both contain HEME
myoglobin
hemoglobin
red plasma cells plus red urine =
hemoglobin
clear plasma cells plus red urine =
myoglobin
chemical differentiation for myoglobin/hemoglobin in urine
based on ammonium sulfate precipitation test
amount of bilirubin present in serum in healthy subjects is _____
small (less than 10% of total bilirubin)
elevated amount of conjugated serum bilirubin implies: (2)
liver diseases
cholestatic diseases
Unconjugated bilirubin is tightly bound to _____, not filtered by the ____ and absent from urine even with raised serum levels of unconjugated bilirubin.
albumin
glomerulus
A positive test for urine bilirubin confirms that any raised plasma levels are from
conjugated hyperbilirubinemia
(2) reasons for false positive urine bilirubin
technique errors
atypical color reactions
(3) reasons for false negative urine bilirubin
large amounts of absorbic acid decrease sensitivity of dipstick
high levels of nitrate
exposure to light and room temperature
urine bilirubin confirmation test
ictotest
urine bilirubin may indicate:
gallbladder, blue duct obstruction or liver pathology
urobilirubin is ______ color and oxidizes to _____, ____ color
colorless
urobilin (brown)
10-15% of urobilinogen is ________ and returned to liver, then _____ in intestines
reabsorbed in bloodstream
re-excreted
normal level or urobilinogen
1-4 mg/24 hour period or less than 0.1 Herlich
false positive for urobilinogen
aspirin
sulfunamides
nitrites
porphyria
false negative for urobilinogen
use of stale urine
formalin
antibiotics
significance of urobilinogen in urine
normally present in small amounts
peaks btwn 2-4:00 pm
elevated in liver disease, intestinal obstruction, hemolytic anemia
_____ test is a rapid, indirect method for the early detection of significant and asymptomatic bacteriuria
nitrate
nitrates are present in normal ____, and are _____ soluble and present in ____
diets
water- soluble
urine
Nitrates converted to nitrites by many bacteria, indicates presence of ____
UTI
common organisms that can cause UTIs
escherichia coli enterobacter citrobacter klebsiella proteus species
to test for UTI caused by NITRITES, urine must have incubated in the bladder for a minimum of ____ , If UTI is caused by only non-nitrate reducers, the reaction will be ___
4 hours (usually first morning urine is specimen of choice) negative
false positive for urine nitrite
air exposure to dipstick
false negative for urine nitrites (6)
specimen containing non-nitrate reducers insufficient time in bladder low or no nitrate diet elevated specific gravity of urine high level of urobilinogen in urine ascorbic acid
significance for urine nitrite
screening method for UTI
leukocyte esterase is only present in _____ ; and few ______ seen in urine
neutrophils
neutrophils
increased # of neutrophils indicates presence of ____
UTI
screening for UTI includes:
neutrophils, pH, protein, nitrite
(3) reasons for leukocyte esterase false positive
trichomonas infxn
contamination by vaginal discharge
formalin used as preservative
(3) reasons for leukocyte esterase false negative
high level ascorbic acid
high level protein or glucose
some antibiotics
