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[MT 6317] Clinical Chemistry Lecture > [2S] UNIT 4 Non-Protein Nitrogen Compounds: Creatinine & Creatine and Ammonia > Flashcards

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

1
Q

C4H7N3O

A

Creatinine

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2
Q

Waste product of creatine formed during normal MUSCLE
METABOLISM

A

Creatinine

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2
Q

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

A

Creatinine

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2
Q

Readily filtered by glomerulus, NOT REABSORBED by tubules

A

Creatinine

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3
Q

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

A

INVERSELY

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4
Q

Used to assess renal filtration function

A

Creatinine

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5
Q

C4H9N3O2

A

Creatine

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6
Q

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

A

GAM
Glycine
Arginine
Methionine

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7
Q

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

A

Creatine

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8
Q

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

A

Creatine

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9
Q

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

A

PHOSPHORIC ACID
WATER

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10
Q

T/F: Creatine can be measured by HPLC

A

T

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11
Q

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

A

T

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12
Q

CLINICAL APPLICATION

Determine the sufficiency of kidney function

A

Creatinine

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13
Q

CLINICAL APPLICATION

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

A

Creatinine

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13
Q

CLINICAL APPLICATION

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

A

URINARY CREATININE

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14
Q

CLINICAL APPLICATION

is used to gauge RENAL FUNCTION

A

GFR

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15
Q

CLINICAL APPLICATION

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

A

Creatinine Clearance

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16
Q

CLINICAL APPLICATION

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

A

Creatinine Clearance

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16
Q

Specimen : Urine

Volume is wrong
Pee smells like ammonia

A

Patient has to collect again

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17
Q

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

A

T

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18
Q

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

A

mL/min

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19
Q

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

A

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

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20
Q

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

A

Plasma Creatinine

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21
Q

CREATININE: ANALYTICAL METHODS

Creatinine + NaOH & picric acid → alkaline picrate complex

A

Jaffe Reaction

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22
Q

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)

A

Jaffe Reaction

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23
Q

CREATININE: ANALYTICAL METHODS

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

A

Jaffe Reaction

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24
Q

CREATININE: ANALYTICAL METHODS

aluminum magnesium silicate

A

Fuller’s earth

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25
Q

CREATININE: ANALYTICAL METHODS

sodium aluminum silicate

A

Lloyd’s reagent

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26
Q

CREATININE: ANALYTICAL METHODS

is used to isolate creatinine from non-creatinine chromogen

A

Aluminum silicate

26
Q

CREATININE: ANALYTICAL METHODS

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

A

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

27
Q

CREATININE: ANALYTICAL METHODS

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

A

Kinetic Jaffe Reaction

28
Q

CREATININE: ANALYTICAL METHODS

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

A

Kinetic Jaffe Reaction

29
Q

CREATININE: ANALYTICAL METHODS

3,5-Dinitrobenzoic acid Method (DNBA) to form purple-colored compound

A

3-5, DINITROBENZOIC ACID (DNBA) METHOD

30
Q

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)

A

3-5, DINITROBENZOIC ACID (DNBA) METHOD

31
Q

CREATININE: ANALYTICAL METHODS

Purple color is proportional to the amount of creatinine present.

A

3-5, DINITROBENZOIC ACID (DNBA) METHOD

32
Q

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)

A

3-5, DINITROBENZOIC ACID (DNBA) METHOD

33
Q

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)

A

Creatininase H202

34
Q

CREATININE: ANALYTICAL METHODS

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

35
Q

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)

A

Creatininase - CK (Creatine kinase)

36
Q

CREATININE: ANALYTICAL METHODS

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

37
Q

Specimen requirement for creatinine / creatine

A

Plasma, Serum, Urine

37
Q

T/F: Fasting is not required for creatinine

37
Q

CREATININE SOURCES OF ERRORS

causes a negative bias in both Jaffe and enzymatic methods

38
Q

CREATININE SOURCES OF ERRORS

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

A

F; Increase

39
Q

CREATININE SOURCES OF ERRORS

will interfere in enzymatic methods that use peroxidase as a reagent

40
Q

CREATININE SOURCES OF ERRORS

Patients taking _______ may have falsely elevated results when the Jaffe reaction is used

A

cephalosporin antibiotics

41
Q

CREATININE SOURCES OF ERRORS

causes a positive bias in some enzymatic methods

42
Q

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

43
Q

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

44
Q

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

45
Q

● 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

46
Q

CLINICAL APPLICATION

To assess if there is liver failure.

47
Q

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.

A

Reye’s Syndrome

48
Q

CLINICAL APPLICATION

● Inherited deficiency of urea cycle enzymes
● Monitor hyperalimentation therapy

A

Reye’s Syndrome

49
Q

PATHOPHYSIOLOGY OF AMMONIA

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

A

neurotoxic

50
Q

PATHOPHYSIOLOGY OF AMMONIA

is associated with inherited deficiency of urea cycle enzymes.

A

Hyperammonemia

51
Q

AMMONIA: ANALYTICAL METHODS

Exploited the volatility of ammonia to separate the compound in a microdiffusion chamber

52
Q

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

53
Q

AMMONIA: ANALYTICAL METHODS

● Thin Film Colorimetry
● NH3 + bromophenol blue blue color

A

Spectrophotometric

53
Q

AMMONIA: ANALYTICAL METHODS

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

A

Enzymatic Method - Catalyzed by GLDH

54
Q

AMMONIA: ANALYTICAL METHODS - Spectrophotometric

The intensity of the color is associated with the amount of ammonia present. The higher the ammonium concentration the darker

A

Dry Slide Automated System

55
Q

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

A

Ion-Selective Electrode

56
Q

AMMONIA DETERMINATION

● Ammonia is isolated
● Eluted with NaCl

A

Cation Exchange Resin

57
Q

AMMONIA DETERMINATION

Cation Exchange Resin is quantified by?

A

Berthelot’s Reaction

58
Q

Specimens for Ammonia

A

Plasma / Urine

59
Q

SPECIMEN REQUIREMENTS FOR AMMONIA

Frozen plasma is stable for several days at?

60
Q

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)

A

Heparin & EDTA

61
Q

SPECIMEN REQUIREMENTS FOR AMMONIA

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

62
Q

SPECIMEN REQUIREMENTS FOR AMMONIA

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

A

F; increase ammonia in plasma

62
Q

SPECIMEN REQUIREMENTS FOR AMMONIA

T/F: Diphenhydramine, Lactobacillus acidophilus, lactulose, levodopa, and several antibiotics decrease concentrations

62
Q

SOURCES OF ERROR

● Tobacco Smoke
● Urine
● Ammonia in detergents
● Glassware
● Reagents
● Water

62
Q

AMMONIA REFERENCE INTERVALS

T/F: Higher concentrations are seen in newborns

[MT 6317] Clinical Chemistry Lecture (9 decks)

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