Creatinine Prt. 2

Question 1

Creatinine (MW 113 Da) is the cyclic anhydride of creatine that is produced as the final product of decomposition of________.

It is excreted in the urine; measurements of ______ and its renal clearance are used as diagnostic indicators of kidney function.

Answer 1

phosphocreatine

plasma creatine

Question 2

Creatine is synthesized in the (3)

Answer 2

(1) kidneys
(2) liver
(3) pancreas

Question 3

Interconversion of phosphocreatine and creatine is a particular feature of the metabolic processes of______

Answer 3

muscle contraction

Question 4

A proportion of the free creatine in muscle (thought to be between 1% and 2% per day) spontaneously and irreversibly converts to its anhydride waste product-______.

Answer 4

creatinine

Question 5

Thus, the amount of creatinine produced each day is relatively constant end is related to the______

Answer 5

muscle mass

Question 6

In health, the concentration of creatinine in the bloodstream also is relatively constant.

However, depending on the inclividual’s_____ intake, diet may influence the value.

Answer 6

meat

Question 7

Creatinine is present in all body fluids and secretions, and is freely filtered by the glomerulus.

Creatinine production also decreases as the circulating level of creatinine increases;

several mechanisms for this have been proposed, including (3)

Answer 7

(1) feedback inhibition of production of creatine

(2) reconversion of creatinine to

(3) conversion to other metabolites

Question 8

The methods most frequently used to measure creatinine are based on the_______ first described in 1886.

In this reaction, creatinine reacts with ______ in_____ solution to form a________.

Answer 8

Jaffe reaction

picric acid

alkaline

red-orange chromogen

Question 9

Jaffe reaction was adopted for the measurement of blood creatinine by_______ in 1919.

Answer 9

Folin and Wu

Question 10

Jaffe reaction

The reaction is nonspecific and subject to positive interference by a large number of compounds, including; AAAGP

Answer 10

acetoacetate
acetone
ascorbate
glucose
pyruvate

Question 11

More accurate results are obtained when creatinine in a protein-free filtrate is adsorbed into______ (aluminum magnesium silicate) or_____ (sodium alurninum silicate) then eluted and reacted with alkaline picrate.

Because this method is time consuming and not readily automated, it is not used routinely.

Answer 11

Fuller’s earth

Lloyd’s reagent

Question 12

Because this method is time consuming and not readily automated, it is not used routinely.

Answer 12

Fuller’s Earth

Lloyd’s reagent

Question 13

Fuller’s earth

Answer 13

(aluminum magnesium silicate)

Question 14

Lloyd’s reagent

Answer 14

(sodium alurninum silicate)

Question 15

Two approaches have been developed to increase the specificity of assay methods for creatinine:

Answer 15

a kinetic Jaffe method and reaction with various enzymes.

Question 16

In the________, serum is mixed with alkaline picrate and the rate of change in absorbarice is measured.

Although this method eliminates some of the nonspecific reactants, it is subject to interference by -keto (2-oxo) acids and cephalosporins.

Answer 16

kinetic Jaffe method

Question 17

Bilirubin and hemoglobin may cause a negative bias, probably a result of their destruction in the strong base used.

The_______ is used despite these problems because it is rapid, inexpensive, and easy to perform.

Answer 17

kinetic Jaffe method

Question 18

In kinetic Jaffe method

(2) may cause a negative bias, probably a result of their destruction in the strong base used.

Answer 18

Bilirubin
hemoglobin

Question 19

In an effort to enhance the specificity of the Jaffe reaction, several coupled enzymatic methods have been developed.

The method using _____

was adapted for use on a dry slide analyzer.

Answer 19

Creatinase
Sarcosine oxidase
Peroxidase

Question 20

is now used as a reference method.

Answer 20

Isotope Dilution Mass Spectrometry

Question 21

Creatinine may be measured in

Answer 21

plasma, serum, or urine

Question 22

____ and _____samples should be avoided, particularly if a Jaffe method is used.

Answer 22

Hemolyzed and icteric

Question 23

_______ may yield erroneous results in some methods.

A______ is not required, although high protein ingestion may transiently elevate serum concentrations.

Answer 23

Lipemic samples

fasting sample

Question 24

Urine should be______ after collection or

frozen if longer storage than____ days is required.

Answer 24

Refrigerated

4days

Question 25

(4) may increase creatinine concentration measured by the Jaffe reaction, especially at temperatures above 30°C.

This interference is significantly decreased when_____ measurement is applied.

Answer 25

AGKU

Ascorbate
glucose
ketoacids
uric acid

kinetic

Question 26

Depending on the concentration of reactants and measuring time, interference from____ may persist in kinetic Jaffe methods.

Some of these substances interfere in enzymatic methods for creatinine measurement.

Answer 26

ketoacids

Question 27

causes a negative bias in both Jaffe and enzymatic methods.

Answer 27

Bilirubin

Question 28

will interfere in enzymatic methods that use peroxidase as a reagent.

Answer 28

Ascorbate

Question 29

Patients taking_____ antibiotics may have falsely increased results when the Jaffe reaction is used.

Answer 29

cephalosporin

Question 30

______particular, is known to affect both Jaffe and enzymatic methods.

_____ causes a positive bias in some enzymatic: methods.

Answer 30

Dopamine

Lidocaine