CREATININE, CREATININE LABORATORY METHODS (TOPIC 3 NON-PROTEINS)

Question 1

Principal waste product of muscle

Answer 1

Creatinine

Question 2

Formed in the muscle and excreted in urine without reabsorption

Answer 2

Creatinine

Question 3

Creatinine is derived from?

Answer 3

arginine
glycine
methionine

Question 4

Used as an accurate monitor to kidney function.

Answer 4

Creatinine

Question 5

Metabolism of creatinine

Answer 5

Creatine (synthesized from arginine, glycine, methionine in the liver then transported to muscle) –> Creatinine Phosphate (Creatinine converted to creatinine phosphate, which gives energy to muscles) –> Creatinine (end product of muscle metabolism, diffuses in plasma, excreted in urine)

Question 6

Creatinine can be measured in

Answer 6

urine
plasma
serum

Question 7

Creatinine specimen

Answer 7

non-fasting

Question 8

produce erroneous result in creatinine

Answer 8

hemolyzed
icteric
lipemic

Question 9

Creatinine determination Chemical method

Jaffe’s reaction (classical method)

Answer 9

Creatinine reacts with picric acid in alkaline medium to develop a red orange color. Not specific due to interferences of glucose, proteins, bilirubin, hemoglobin, ascorbic acid, ketones and pyruvate.

Creatinine + picric acid –(10% NaOH (alkaline medium)–> red orange color

Question 10

Creatinine determination Chemical method

Jaffe reaction (kinetic)

Answer 10

Serum is mixed with alkaline picrate and the rate of change absorbance is measured

Absorbance read only at 80 and 120 seconds
Routinely used

Question 11

Lloyd’s reagent method silicate (sodium aluminum silicate) or Fuller’s earth (aluminum magnesium silicate).

Answer 11

Creatinine in a protein-free filtrate is adsorbed onto Fuller’s earth or Lloyd’s reagent then eluted and reacted with alkaline picrate.

Question 12

Folin Wu method

Answer 12

Sensitive but not specific due to interference of acetoacetate, acetone, ascorbate, glucose, and pyruvate.

Question 13

Creatinine Determination (enzymatic method)

Creatinine-H2O2

Answer 13

Creatinine –(up arrow) Creatininase, (down arrow) converted –> Creatine –(creatinase (creatine amidohydrolase)–> sarcosine

Sarcosine –(up arrow)Sarcosine oxidase, (down arrow)oxidized –> Hydrogen Peroxide

H2O2 (colorless) + peroxidase –> colored product

Measured at 550 nm

Question 14

Creatinine Determination (enzymatic method)

Creatininase-CK

Answer 14

Creatinine is converted to creatine then to NAD by series of enzyme reactions of

Creatinine Kinase
Pyruvate Kinase
Lactate dehydrogenase

NAD measure 340 nm

Question 15

Creatinine Determination (enzymatic method)

Creatininase deaminase

Answer 15

Creatinine –(creatinase)–> n-methylhydantoin +NH3

NH3 + alpha-ketoglutarate + NADPH –(Glutamate Dehydrogenase)–> Glutamate + NAD

Question 16

Creatinine determination (chromatography)

Answer 16

GC-IDMS- Gas chromatography-isotype dilution mass spectrophotometry.

HPLC-The most sensitive method of determining the true value of creatinine in the blood.

Question 17

Creatinine determination method mostly used method

Answer 17

Jaffe Reaction

Question 18

Creatinine Normale Value

Male
Female
Conversion Factor

Answer 18

0.6-1.2
0.5-1.1 mg/dl
x 88.4

Question 19

Increase Serum Creatinine in?
Decrease in?

Answer 19

High protein Diet
Creatine Supplement
Muscle Mass
Drugs
Dehydration

Muscle Wasting Disease (muscular dystrophy) e.g. duchenne muscular dystrophy

Question 20

BUN creatinine Ratio
Normal Value

Answer 20

10:1 - 20:1

Question 21

use to identify the type of azotemia

Answer 21

BUN-creatinine ration