creatinine Flashcards
t/f Creatinine is primarily formed from amino acids arginine and methionine
F - from creatine and creatine phosphate
primary source of creatinine in the body
muscle catabolism
Creatine is converted to __________ via the creatine kinase enzyme
creatine phosphate
Select: Creatinine
A) It is synthesized in the kidneys.
B) It is a product of muscle metabolism.
C) It is not filtered by the glomerulus.
D) It has no relation to kidney function.
B
Select: Creatinine
A) 99% of creatinine is reabsorbed in the kidneys.
B) Creatinine is formed from creatine and creatine phosphate.
C) Creatinine levels are unaffected by muscle mass.
D) Creatinine is synthesized only in the kidneys
B
T/F creatinine levels in the plasma are inversely related to glomerular filtration rate (GFR).
t (the higher the plasma creatinine, the lower the glomerular filtration rate)
Creatinine is excreted primarily in the __________
urine
t/f Creatinine is mostly reabsorbed by the kidneys.
F - 99% of creatinine is excreted in urine and <1% is reabsorbed
relationship between muscle mass and creatinine levels
Larger muscle mass leads to higher creatinine levels
OOO: Affects creatinine levels
A) Muscle mass
B) Age
C) Renal function
D) Creatine turnover
B
t/f creatinine is completely reabsorbed by the kidneys after filtration
f - less than 1% is reabsorbed
Creatinine is a product of the catabolism of __________
muscle
t/f Monitoring plasma creatinine levels can help assess kidney function
T
Select: Indication of increase in plasma creatinine
A) Improved kidney function
B) Decreased kidney function
C) Increased muscle mass
D) Dehydration
B
t/f Creatinine is synthesized in the liver from arginine, glycine, and methionine.
t
what happens to creatine phosphate in muscle tissue
loses phosphoric acid to form creatinine
cyclic compound formed from the loss of water from creatine
creatinine
t/f Creatinine is used as an energy source by muscles
F - Creatine phosphate is used as a high-energy source, not creatinine
t/f Jaffe reaction is the most frequently used method for measuring creatinine.
t
t/f Jaffe reaction is a chemical method used to determine creatinine levels
t
main principle of the Jaffe reaction
creatinine reacts with picric acid in an alkaline medium to form a creatinine-picrate complex.
Select: Main difference in timing for the Kinetic Jaffe method
A) Reaction time is not important
B) Incubation time and absorbance readings are critical
C) Absorbance should be read after 5 minutes only
B
The Jaffe reagent is a combination of picric acid and 10% __________
sodium hydroxide
*Picric acid (Reagent 1); sodium hydroxide with disodium phosphate (Reagent 2)
The intensity of the orange-red product formed in the Jaffe reaction is __________ to the amount of creatinine present
directly proportional
T/F The Folin-Wu method requires the use of an adsorbent
F - Folin-Wu method does not use adsorbents
t/f Folin-Wu method is specific and not prone to false positives.
F - non-specific and can give false positives with substances like ascorbic acid and glucose
Select: False-positive results in the Folin-Wu method
A) Ascorbic acid
B) Sodium chloride
C) Glucose
D) Uric acid
E) Insulin
F) Hemoglobin
A C D
T/F Jaffe method with adsorbent is more accurate than the Folin-Wu method.
T
adsorbent used in the Jaffe with adsorbent method to improve accuracy
Fuller’s earth (aluminum magnesium silicate)
Lloyd’s reagent (sodium aluminum silicate).
role of fuller’s earth or Lloyd’s reagent in the Jaffe method with adsorbent
adsorb creatinine from a protein-free filtrate
measures the rate of change in absorbance to avoid interference from non-creatinine chromogens
Jaffe kinetic
t/f Jaffe kinetic methods are not routinely performed due to high costs
f - routinely performed because they are inexpensive and easy to execute
t/f Kinetic methods for measuring creatinine levels are less expensive and more rapid than other methods.
t
Select: False positive in Jaffe kinetic methods
A) Alpha-keto acids
B) Bilirubin
C) Cephalosporins
D) Hemoglobin
A C
*B D - false negative
Creatininase converts creatinine to __________
creatine
t/f Creatinase converts creatine to sarcosine and urea
t
enzyme that oxidizes sarcosine to form formaldehyde and glycine
sarcosine oxidase
reaction catalyzed by peroxidase measures the __________ produced in the reaction.
peroxide
Accepted reference method for measuring creatinine
Isotope dilution mass spectrometry
t/f Fasting is required before measuring creatinine levels.
f
type of specimens can be used for creatinine measurement
plasma, serum, or urine
T/F High protein ingestion can increase creatinine levels.
F - may transiently elevate serum creatinine concentration, but not significant to increase creatinine levels
t/f Hemolysis, lipemia, and icteric samples can interfere with the Jaffe reaction.
t
If samples cannot be processed immediately, they must be __________.
refrigerated
t/f urine samples that are not processed within 4 days can be frozen.
t
reagent used in the creatinine reagent kit to create the Jaffe reaction
picric acid
standard creatinine concentration is __________ mg/dL or 176.8 mmol/L
2 mg/dL
t/f procedure for measuring creatinine levels requires mixing reagents before adding them to the sample
t
at what wavelength should the spectrophotometer be set for measuring creatinine
520 nm
incubation temperature for the creatinine assay is __________ °C
37
Sequence: Creatinine Procedure
A) Set up the spectrophotometer at 520 nm.
B) Add the reagent by touching the pipet tip to the bottom of the tube.
C) Mix the solution by covering the mouth of the tube with parafilm.
D) Deliver the sample volume by touching the pipet tip to the bottom of the tube.
E) Read and record absorbance at 10 seconds as A1.
D A B C E
t/f absorbance is recorded twice during the procedure: once at 10 seconds and again at 120 seconds
t
optical path used in the assay is __________ cm.
1 cm
conversion factor from mg/dL to µmol/L is ____
88.402
reference range for plasma/serum creatinine for adult males using the Jaffe method
0.9 - 1.3 mg/dL or 80 - 115 µmol/L
reference range for plasma/serum creatinine for adult females using the enzymatic method is __________ mg/dL or __________ µmol/L.
0.5 - 0.8 mg/dL or 44 - 71 µmol/L
reference ranges for children using the Jaffe method
0.3 - 0.7 mg/dL
0.6 - 1.1 mg/dL or 53 - 97 µmol/L.
t/f There is no significant difference in creatinine reference ranges between males, females, and children
f
urine creatinine reference range for adult males over 24 hours
800 - 2000 mg/day or 7.1 - 17.7 mmol/day
urine creatinine reference range for adult females over 24 hours is __________ mg/day or __________ mmol/day
600 - 1800 mg/day or 5.3 - 15.9 mmol/day
t/f Creatinine concentration in the body is independent of body mass.
f
reference range for plasma/serum creatinine for adult males using the enzymatic method is __________ mg/dL or __________ µmol/L.
0.67 - 1.1 mg/dL or 53 - 97 µmol/L
reference range for children using the enzymatic method
0.0 - 0.6 mg/dL
0 - 53 umol/L
reference range for adult females using the Jaffe method is __________ mg/dL or __________ µmol/L
0.6 - 1.1 mg/dL or 53 - 97 µmol/L.
Measure of the amount of creatinine eliminated from the blood by the kidneys
creatinine clearance
t/f Creatinine clearance (CrCl) is used to determine the glomerular filtration rate.
t
primary analyte used to approximate the glomerular filtration rate
creatinine
Select: Factors considered for determining glomerular filtration rate
A) Analyte should be endogenously produced.
B) Analyte should be externally supplied.
C) Analyte should not be excreted in urine.
D) Analyte should be or almost 100% is
excreted in the urine
A D
formula for creatinine clearance
CrCl = (Ucr x Vu) / Pcr x t [(Urine creatinine x Urine volume) / (Plasma creatinine x Time)]
CrCl = Ucr x urine vol in 24h / Pcr x 1440
t/f when collecting a 24-hour urine sample, the first urine voided at the start time should be included in the collection
f
average body surface area (BSA) of an adult male used in the corrected creatinine clearance formula
1.73
Formula for Corrected Creatinine Clearance
CrCl = [(Ucr x Vu) / Pcr x t ] x (1.73/A)
normal creatinine clearance range for males
97-137 ml/min
normal creatinine clearance range for females is __________ mL/min.
88-128 mL/min
Select: increase creatinine clearance
A) Impaired renal function
B) Acute kidney injury
C) Chronic kidney disease
D) Muscle wasting
A B C
T/f If there is an decrease in plasma creatinine, this is most likely due to impaired renal function or a kidney
disease.
increase
chemical formula of creatinine
C4H7N3O
t/f creatinine is the anhydride of creatine, which has the chemical formula C4H9N3O2.
t
Select: Affect the total daily production of creatinine
A) Meat ingestion
B) Water intake
C) Vitamin supplements
D) Exercise
A
t/f Creatinine clearance is reported in liters per minute (L/min)
f - ml/min
T/F Creatinine levels in plasma are a sensitive marker for early renal dysfunction
F - Plasma creatinine is an insensitive marker for mild or early renal dysfunction; renal damage must be more than 50% to detect changes.
OOO: increased creatinine and urinary creatinine
A) Muscular dystrophy
B) Hyperthyroidism
C) Liver cirrhosis
D) Poliomyelitis
C
Creatinine is considered a more reliable kidney function test because it is not affected by diet, dehydration, or __________ metabolism
protein
t/f creatininase-H2O2 method is free from interferences by acetoacetate or cephalosporins but may be affected by lidocaine
t
OOO: Control used in creatinine determination
A) Ellitrol 1
B) Ellitrol 2
C) Citrate control
C
t/f spectrophotometer should be set up after adding the reagent in the Kinetic Jaffe method
F - should be set up prior to adding the reagent
In the Kinetic Jaffe method, the absorbance is read at 7 seconds (A1) and exactly __________ minutes (A2).
2 minutes
formula for calculating the concentration of creatinine in 24-hour urine
C (mg/24hr) = mg/dL x urine volume (mL) x 0.01.
OOO: Kinetic Jaffe procedure
A) Mixing the solution by inverting the tubes
B) Reading the absorbance at 7 seconds
C) Incubating for 10 minutes at room temperature
C
formula for calculating creatinine in 24-hour urine in mmol/24hr is mg/24hr x _________
0.00884
coversion factor umol/L to mg/dL
x 0.0113
