creatinine/creatine Flashcards
1
Q
the normal BUN/CREATININE RATIO is (?) to (?)
* in prerenal disease, it rises to (?)
* in true renal disease, both BUN and CREATININE (?)
A
- 10:1, 20:1
- > 20:1
- rise together
2
Q
creatinine methods
- creatinine in protein-free filtrate adsorbed onto fuller’s earth (aluminum magnesium silicate), then reacted with alkaline picrate to form colored complex
- adsorbent improves specificity; previously considered reference method
A
jaffe with adsorbent
3
Q
- formed from creatine (synthesized primarily in the liver from arginine, glycine and methionine) and creatine phosphate in muscle
- excreted in plasma at a constant rate related to muscle mass
- daily excretion is fairly stable thus it is commonly used to assess renal filtration function
A
creatinine
4
Q
creatinine methods
measure ammonia colorimetrically or with ISE
A
enzymatic
5
Q
creatinine methods
jaffe reaction
* in alkaline solution + picrate = (?) complex
A
red-orange
6
Q
creatinine methods
- creatinine in protein-free filtrate reacts with alkaline picrate to form colored complex
- positive bias from ascorbic acid, glucose, glutathione, a-keto acids, uric acid, and cephalosporins
A
jaffe without adsorbent
7
Q
creatinine methods
simple, nonspecific
A
end point (colorimetric)
8
Q
creatinine methods
rapid, increased specificity
A
kinetic (colorimetric)
9
Q
creatinine methods
- in a series of enzymatically catalyzed reactions, creatinine is hydrolyzed to creatine, which is converted to sarcosine and urea. Sarcosine is oxidized to glycine, CH2O, and H2O2. Peroxidase-catalyzed oxidation of a colorless substrate produces a colored product + H2O
- adapted for use as dry slide method; potential to replace jaffe; no interference from acetoacetate or cephalosphorins; some positive bias due to lidocaine
A
creatinase-H2O2
10
Q
creatinine
clinical application
* determine sufficiency of (?) and (?)
* monitor the progression of (?)
* measure completeness of (?) collection
A
- kidney function, severity of disease
- kidney disease
- 24 hour
11
Q
creatinine methods
- in a series of reactions catalyzed by the enzymes creatininase, creatine kinase, pyruvate kinase, and lactate dehydrogenase, NAD+ is produced and measured as a decrease in absorbance
- lacks sensitivity, not used widely
A
creatininase CK
12
Q
creatinine methods
- jaffe reaction performed directly/on sample; detection of color formation timed to avoid interference of noncreatinine chromogens
- positive bias from a-keto acids and cephalosporins; requires automated equipment for precision
A
jaffe kinetic
