[2S] UNIT 4 Non-Protein Nitrogen Compounds: Creatinine & Creatine and Ammonia

Question 1

C4H7N3O

Answer 1

Creatinine

Question 2

Waste product of creatine formed during normal MUSCLE
METABOLISM

Answer 2

Creatinine

Question 2

is formed from creatine and creatine phosphate in muscle and is excreted into the plasma at a constant rate related to muscle mass

Answer 2

Creatinine

Question 2

Readily filtered by glomerulus, NOT REABSORBED by tubules

Answer 2

Creatinine

Question 3

Plasma creatinine is ________ RELATED to glomerular filtration rate (GFR)

Answer 3

INVERSELY

Question 4

Used to assess renal filtration function

Answer 4

Creatinine

Question 5

C4H9N3O2

Answer 5

Creatine

Question 6

Creatine is produced by the liver and pancreas from [3 amino acids]

Answer 6

GAM
Glycine
Arginine
Methionine

Question 7

Enters the bloodstream and distribute in cell especially in the muscle, where it is converted to PHOSPHOCREATINE

Answer 7

Creatine

Question 8

is transported to other tissues – muscle - converted to creatine phosphate (high-energy source)

Answer 8

Creatine

Question 9

Creatine phosphate loses ________ and creatine loses ________ to form the cyclic compound, creatinine

Answer 9

PHOSPHORIC ACID
WATER

Question 10

T/F: Creatine can be measured by HPLC

Answer 10

T

Question 11

T/F: Decreased in muscular dystrophy or poliomyelitis, hyperthyroidism, trauma
○ Seen in increased urine and plasma creatine but NORMAL creatinine level (constant)
○ Plasma creatine levels ARE NOT ELEVATED in renal diseases

Answer 11

T

Question 12

CLINICAL APPLICATION

Determine the sufficiency of kidney function

Answer 12

Creatinine

Question 13

CLINICAL APPLICATION

○ Determine the severity of kidney damage
○ Monitor the progression of kidney disease

Answer 13

Creatinine

Question 13

CLINICAL APPLICATION

__________ _________excretion has been used as a measure of the completeness of 24-hour urine collections

Answer 13

URINARY CREATININE

Question 14

CLINICAL APPLICATION

is used to gauge RENAL FUNCTION

Answer 14

GFR

Question 15

CLINICAL APPLICATION

defined as the volume of blood being cleared of urea per unit time (mL/min) (Acc. to Ma’am)

Answer 15

Creatinine Clearance

Question 16

CLINICAL APPLICATION

a measure of the amount of creatinine ELIMINATED from the blood by the kidneys

Answer 16

Creatinine Clearance

Question 16

Specimen : Urine

Volume is wrong
Pee smells like ammonia

Answer 16

Patient has to collect again

Question 17

T/F: Plasma creatinine is insensitive to mild renal dysfunction

Answer 17

T

Question 18

CrCl is usually reported in units of _____ and can be corrected for body surface area

Answer 18

mL/min

Question 19

T/F: CrCl requires either a VENOUS BLOOD DRAW or A 24-HOUR URINE collection specimen

Answer 19

F; CrCl requires both a VENOUS BLOOD DRAW AND A 24-HOUR URINE collection specimen

Question 20

DOES NOT provide sufficient sensitivity for the detection of mild renal dysfunction

Answer 20

Plasma Creatinine

Question 21

CREATININE: ANALYTICAL METHODS Creatinine + NaOH & picric acid → alkaline picrate complex

Answer 21

Jaffe Reaction

Question 22

CREATININE: ANALYTICAL METHODS Protein-free filtrate mixed with alkaline picrate solution forms a red-orange “tautomer” of creatinine picrate, which absorbs light at 520 nm that is proportional to the amount of creatinine present ○ Endpoint measurement (product form is measured)

Answer 22

Jaffe Reaction

Question 23

CREATININE: ANALYTICAL METHODS Interferences: chromogens / Jaffe (+) substances ○ Acetoacetic acid ○ Pyruvic acid ○ Ascorbate ○ Acetone ○ Glucose

Answer 23

Jaffe Reaction

Question 24

CREATININE: ANALYTICAL METHODS aluminum magnesium silicate

Answer 24

Fuller's earth

Question 25

CREATININE: ANALYTICAL METHODS sodium aluminum silicate

Answer 25

Lloyd’s reagent

Question 26

CREATININE: ANALYTICAL METHODS is used to isolate creatinine from non-creatinine chromogen

Answer 26

Aluminum silicate

Question 26

CREATININE: ANALYTICAL METHODS ● Elution techniques are then utilized sensitive and specific method ● Time-consuming and not readily automated, therefore, not routinely performed

Answer 26

Jaffe with Adsorbent (Lloyd's / Fuller's Earth)

Question 27

CREATININE: ANALYTICAL METHODS ● Jaffe reaction performed directly on sample ● Used routinely; inexpensive, rapid, and easy to perform

Answer 27

Kinetic Jaffe Reaction

Question 28

CREATININE: ANALYTICAL METHODS ● Interference (positive bias) from alpha-keto acids and cephalosporins ● Negative bias may be caused by bilirubin and hemoglobin

Answer 28

Kinetic Jaffe Reaction

Question 29

CREATININE: ANALYTICAL METHODS 3,5-Dinitrobenzoic acid Method (DNBA) to form purple-colored compound

Answer 29

3-5, DINITROBENZOIC ACID (DNBA) METHOD

Question 30

CREATININE: ANALYTICAL METHODS ● Used in reagent strips (solid phase reflectance spectroscopy) ● Creatinine + DNBA (OH-) ● Product: purple-colored compound read at 560 nm (Benedict-Behre reaction)

Answer 30

3-5, DINITROBENZOIC ACID (DNBA) METHOD

Question 31

CREATININE: ANALYTICAL METHODS Purple color is proportional to the amount of creatinine present.

Answer 31

3-5, DINITROBENZOIC ACID (DNBA) METHOD

Question 32

CREATININE: ANALYTICAL METHODS For automated machines only: alkaline 3,5 dinitrobenzoate solution to form orange-red complex ○ Uses alkaline 3,5 dinitrobenzoate solution to form orange-red complex resulting in an increased absorbance and read at 546 nm (linear relationship)

Answer 32

3-5, DINITROBENZOIC ACID (DNBA) METHOD

Question 33

CREATININE: ANALYTICAL METHODS ● Creatinine + H2O → creatine (uses creatininase) ● Creatinine + H2O → sarcosine + urea (uses creatininase) ● Sarcosine + O2 + H2O → glycine + CH2O + H2O2 (uses sarcosine oxidase) ● H2O2 + colorless substrate → colored product + H2O (uses peroxidase)

Answer 33

Creatininase H202

Question 34

CREATININE: ANALYTICAL METHODS T/F: Creatininase - CK : Decreased absorbance is proportional to the amount of creatinine in the specimen

Answer 34

T

Question 35

CREATININE: ANALYTICAL METHODS ● Creatinine + H2O → creatine (uses creatininase) ● Creatine + ATP → creatine phosphate + ADP (uses creatine kinase) ● ADP + phosphoenolpyruvate → pyruvate + ATP (uses pyruvate kinase) ● Pyruvate + NADH + H → lactate + NAD+ (uses lactate dehydrogenase)

Answer 35

Creatininase - CK (Creatine kinase)

Question 36

CREATININE: ANALYTICAL METHODS ● Detection of characteristic fragments following ionization ● Quantification using isotopically labeled compound ● Highly specific ● Accepted reference method

Answer 36

IDMS

Question 37

Specimen requirement for creatinine / creatine

Answer 37

Plasma, Serum, Urine

Question 37

T/F: Fasting is not required for creatinine

Answer 37

T

Question 37

CREATININE SOURCES OF ERRORS causes a negative bias in both Jaffe and enzymatic methods

Answer 37

Bilirubin

Question 38

CREATININE SOURCES OF ERRORS T/F: Ascorbate, glucose, α-keto acids, and uric acid = Decrease creatinine concentration

Answer 38

F; Increase

Question 39

CREATININE SOURCES OF ERRORS will interfere in enzymatic methods that use peroxidase as a reagent

Answer 39

Ascorbate

Question 40

CREATININE SOURCES OF ERRORS Patients taking _______ may have falsely elevated results when the Jaffe reaction is used

Answer 40

cephalosporin antibiotics

Question 41

CREATININE SOURCES OF ERRORS causes a positive bias in some enzymatic methods

Answer 41

Lidocaine

Question 42

● Acquired from protein intake ● Produced from deamination of amino acids

Answer 42

Ammonia

Question 43

● Metabolic reactions in skeletal muscle during exercise ● Consumed by the parenchymal cells of the liver in the production of urea

Answer 43

Ammonia

Question 44

T/F: Most ammonia in the blood exist as ammonium ion, excreted as ammonium ion by the kidney, and acts to buffer urine

Answer 44

T

Question 45

● Measurement of urine ammonia can be used to confirm the ability of the kidney to produce ammonia ● Used to monitor the progress of severe clinical conditions

Answer 45

Ammonia

Question 46

CLINICAL APPLICATION To assess if there is liver failure.

Answer 46

Ammonia

Question 47

CLINICAL APPLICATION ● Blood sugar drops, and blood ammonia and acidity increases. ● Post viral with aspirin ingestion; resulting in hepatic dysfunction due to fatty infiltration of the liver.

Answer 47

Reye's Syndrome

Question 48

CLINICAL APPLICATION ● Inherited deficiency of urea cycle enzymes ● Monitor hyperalimentation therapy

Answer 48

Reye's Syndrome

Question 49

PATHOPHYSIOLOGY OF AMMONIA High concentrations of NH3 are ______ and often associated with hepatic encephalopathy

Answer 49

neurotoxic

Question 50

PATHOPHYSIOLOGY OF AMMONIA is associated with inherited deficiency of urea cycle enzymes.

Answer 50

Hyperammonemia

Question 51

AMMONIA: ANALYTICAL METHODS Exploited the volatility of ammonia to separate the compound in a microdiffusion chamber

Answer 51

Conway

Question 52

AMMONIA: ANALYTICAL METHODS ● Ammonia gas from the sample diffuses into a separate compartment and is absorbed in a solution containing a pH indicator ● The amount of ammonia is determined by titration

Answer 52

Conway

Question 53

AMMONIA: ANALYTICAL METHODS ● Thin Film Colorimetry ● NH3 + bromophenol blue blue color

Answer 53

Spectrophotometric

Question 53

AMMONIA: ANALYTICAL METHODS ● Measures the decrease in absorbance at 340 nm ● Most common on automated instruments ● Accurate and precise

Answer 53

Enzymatic Method - Catalyzed by GLDH

Question 54

AMMONIA: ANALYTICAL METHODS - Spectrophotometric The intensity of the color is associated with the amount of ammonia present. The higher the ammonium concentration the darker

Answer 54

Dry Slide Automated System

Question 55

AMMONIA: ANALYTICAL METHODS ● Direct measurement ● Diffusion of NH3 through selective membrane into NH4Cl causes a pH change, which is measured potentiometrically ● Good accuracy and precision; membrane stability may be a problem

Answer 55

Ion-Selective Electrode

Question 56

AMMONIA DETERMINATION ● Ammonia is isolated ● Eluted with NaCl

Answer 56

Cation Exchange Resin

Question 57

AMMONIA DETERMINATION Cation Exchange Resin is quantified by?

Answer 57

Berthelot's Reaction

Question 58

Specimens for Ammonia

Answer 58

Plasma / Urine

Question 59

SPECIMEN REQUIREMENTS FOR AMMONIA Frozen plasma is stable for several days at?

Answer 59

-20°C

Question 60

SPECIMEN REQUIREMENTS FOR AMMONIA are suitable anticoagulants; samples should be centrifuged at 0 to 4°C within 20 minutes of collection and the plasma removed. (ASAP)

Answer 60

Heparin & EDTA

Question 61

SPECIMEN REQUIREMENTS FOR AMMONIA T/F: It is recommended that patients do not smoke for several hours before a specimen is collected.

Answer 61

T

Question 62

SPECIMEN REQUIREMENTS FOR AMMONIA T/F: Ammonium salts, asparaginase, barbiturates, diuretics, ethanol, hyperalimentation, narcotic analgesics, and some other drugs may decrease ammonia in plasma

Answer 62

F; increase ammonia in plasma

Question 62

SPECIMEN REQUIREMENTS FOR AMMONIA T/F: Diphenhydramine, Lactobacillus acidophilus, lactulose, levodopa, and several antibiotics decrease concentrations

Answer 62

T

Question 62

SOURCES OF ERROR ● Tobacco Smoke ● Urine ● Ammonia in detergents ● Glassware ● Reagents ● Water

Answer 62

Ammonia

Question 62

AMMONIA REFERENCE INTERVALS T/F: Higher concentrations are seen in newborns

Answer 62

T