02 CREATINE & CREATININE Flashcards
The plasma creatinine level is ___ proportional to the GFR
inversely
Used in the diagnosis of muscle disease in place of creatine
Creatine kinase
Muscle dystrophy causes plasma creatine to ___ (increase/decrease) and urinary creatinine to ___ (increase/decrease)
increase
decrease
Poliomyelitis causes plasma creatine to ___ (increase/decrease) and urinary creatinine to ___ (increase/decrease)
increase
decrease
Hyperthyroidism causes plasma creatine to ___ (increase/decrease) and urinary creatinine to ___ (increase/decrease)
increase
decrease
Creatinine is a waste product of ___ formed during normal muscle metabolism
creatine
Creatine is produced by the liver and pancreas from ___, ___, ___
arginine
glycine
methionine
Creatine phosphate loses ___ and creatine loses ___ to form creatinine
phosphoric acid
water
T/F: plasma creatine levels are increased in renal disease
F (not elevated)
A measure of the amount of creatinine eliminated from the blood by the kidneys
Creatinine clearance (CrCl)
Normal range of CrCl in males
97-137 mL/min
Normal range of CrCl in females
88-128 mL/min
Plasma creatinine is sensitive only if the renal dysfunction is at ___%
> 50%
An analyte measured in the blood that is a more sensitive measure than plasma creatinine and is able to detect mild renal dysfunction
Cystatin C
Gold standard for creatinine clearance determination
Inulin clearance
CrCl is usually reported in units of ___ and can be corrected for body surface, which is ___
mL/min
173
T/F: in MDRD and Cockgroft-Gault equations, 24h urine are needed
F
Factors considered in the Cockgroft-Gault equation
Age
Weight
Sex (for women, multiply by 0.85)
Factors considered in the MDRD study equation
Age
Sex (for women, multiply by 0.742)
Race (for Africans, multiply by 1.21)
The chemical method for creatinine determination
Jaffe Reaction
Absorbance of the red-orange tautomer in the Jaffe reaction
520 nm
Positive interferences in the Jaffe method of creatinine determination
Acetoacetic acid
Pyruvic acid
Ascorbate
Acetone
Glucose
Adsorbents used to enhance the accuracy of Jaffe method of creatinine determination
Lloyd’s reagent
Fuller’s earth
Component of Lloyd’s reagent
Sodium aluminum silicate
Component of Fuller’s earth
Sodium magnesium silicate
Used to isolate creatinine from noncreatinine chromogen
Aluminum silicate
Positive interferences in the kinetic Jaffe reaction
Alpha-ketoacids
Cephalosporins
Negative interferences in the kinetic Jaffe reaction
Bilirubin
Hemoglobin
The creatinine determination method that uses reagent strips and produces purple-colored compound
3,5-Dinitrobenzoic acid Method (DNBA)
DNBA is measured at what wavelength?
560 nm
For the automated determination of creatinine level and forms orange-red complex
alkaline 3,5 dinitrobenzoate solution
Alkaline 3,5 dinitrobenzoate solution is measured at what wavelength?
546 nm
Specimens used for creatinine determination
Plasma
Serum
Urine
In using urine for creatinine determination, what must be done?
Refrigerated after collection or frozen if longer storage than 4 days
T/F: in Jaffe method, ascorbate falsely decreases while in the enzymatic method, it falsely increases
F (Jaffe = false increase, enzymatic = false decrease)
In creatinine determination, ___ causes negative bias in both Jaffe and enzymatic methods
Bilirubin
Lidocaine causes a ___ bias in some enzymatic method of creatinine determination
positive
Normal range of creatinine for adult male (Jaffe)
0.9-1.3 mg/dL
Normal range of creatinine for adult female (Jaffe)
0.6-1.1 mg/dL
Normal range of creatinine for children (Jaffe)
0.3-0.7 mg/dL
Normal range of urine creatinine for adult male (Jaffe)
800-2000 mg/dL
Normal range of urine creatinine for adult female (Jaffe)
600-1800 mg/dL
Normal range of creatinine for adult male (enzymatic)
0.6-1.1 mg/dL
Normal range of creatinine for adult female (enzymatic)
0.5-0.8 mg/dL
Normal range of creatinine for children (Enzymatic)
0-0.6 mg/dL
A chemical method of creatinine determination based on Jaffe reaction wherein creatinine in protein-free filtrate reacts with alkaline picrate to form colored complex
Folin-Wu method
T/F: Jaffe reaction with adsorbent is not routinely used because it is time consuming and not readily automated
T
A creatinine determination method that is routinely performed and is inexpensive, rapid, and easy to perform
Jaffe kinetic
A creatinine determination method that is adapted for used as dry slide method
Creatininase-H2O2
T/F: Creatininase-H2O2 can potentially replace Jaffe method
T
Wavelength used in Jaffe kinetic method of creatinine determination
520 nm
Conversion factor of creatinine from conventional to SI unit
88.4
