[2S] UNIT 9.3 Creatinine Flashcards by JULIA CASSANDRA RECCION

Q

Formed from creatine and creatine phosphate

A

Creatinine

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Q

Product of muscle catabolism

A

Creatinine

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Q

99% excreted in urine

A

Creatinine

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Q

Creatinine is filtered in?

A

Glomerulus

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Q

3 Factors affecting creatinine level

A

Muscle Mass
Creatine Turnover
Renal Function

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Q

Creatine loses _____ to form a cyclic compound known as creatinine

A

water

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Q

Creatine phosphate loses _______ ____

A

phosphoric acid

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Q

↑ muscle mass _ creatinine level

A

↑

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Q

↑ plasma creatinine _ glomerular filtration rate

A

↓

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Q

CLINICAL APPLICATIONS

T/F: Determine the sufficiency of kidney function

A

T

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Q

CLINICAL APPLICATIONS

T/F: Determine the severity of heart damage

A

F; kidney damage

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Q

CLINICAL APPLICATIONS

T/F: Monitory progression of kidney disease

A

T

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Q

ANALYTICAL METHODS

● Most frequently used method
● First described in 1886

A

Chemical Methods Based of Jaffe Reaction

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Q

ANALYTICAL METHODS

Principle: In alkaline medium: Creatinine + picric acid → Creatinine-picrate complex (orange red)

A

Chemical Methods Based of Jaffe Reaction

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Q

ANALYTICAL METHODS

The intensity of orange red product is directly proportional to amount of creatinine present

A

Chemical Methods Based of Jaffe Reaction

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Q

ANALYTICAL METHODS: CHEMICAL METHODS BASED OF JAFFE REACTION

Creatinine in a protein-free filtrate is adsorbed onto
fuller’s earth (aluminum magnesium silicate) or
Lloyd’s reagent (sodium aluminum silicate), then
eluted and reacted with alkaline picrate

A

Jaffe w/ Adsorbent

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Q

ANALYTICAL METHODS: CHEMICAL METHODS BASED OF JAFFE REACTION

Non-specific and prone to false positive reactions
with:
○ Ascorbic acid
○ Glucose
○ Glutathione
○ Alpha-keto acids
○ Uric acid
○ Cephalosporins

A

Folin-Wu Method (w/o Adsorbent)

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Q

ANALYTICAL METHODS: CHEMICAL METHODS BASED OF JAFFE REACTION

Creatinine in protein-free filtrate reacts with alkaline
picrate to form colored complex

A

Folin-Wu Method (w/o Adsorbent)

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Q

ANALYTICAL METHODS: CHEMICAL METHODS BASED OF JAFFE REACTION

Measuring multiple absorbance

A

Jaffe Kinetic

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Q

ANALYTICAL METHODS: CHEMICAL METHODS BASED OF JAFFE REACTION

The rate of change in absorbance is measured to
avoid interference of non-creatinine chromogens

A

Jaffe Kinetic

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Q

ANALYTICAL METHODS: CHEMICAL METHODS BASED OF JAFFE REACTION

Not routinely used because it is time consuming and
not readily automated

A

Jaffe w/ Adsorbent

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Q

ANALYTICAL METHODS: CHEMICAL METHODS BASED OF JAFFE REACTION

False positives
○ Alpha-keto acids
○ cephalosporins

A

Jaffe Kinetic

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Q

ANALYTICAL METHODS: CHEMICAL METHODS BASED OF JAFFE REACTION

Routinely performed because
○ Inexpensive
○ Rapid
○ Easy to perform

A

Jaffe Kinetic

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Q

ANALYTICAL METHODS: CHEMICAL METHODS BASED OF JAFFE REACTION

Serum is mixed with alkaline picrate

A

Jaffe Kinetic

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ANALYTICAL METHODS: CHEMICAL METHODS BASED OF JAFFE REACTION False negatives ○ Bilirubin ○ Hemoglobin

Jaffe Kinetic

ENZYMATIC METHODS ● Adapted for use as dry slide method ● Potential to replace Jaffe reaction

Creatininase - H2O2

ENZYMATIC METHODS ● False positives ○ lidocaine ● False negatives ○ Ascorbic acid - interfere with peroxidase reaction

Creatininase - H2O2

ENZYMATIC METHODS Uses series of enzymatic catalyzed reaction

Creatininase - H2O2

ENZYMATIC METHODS ○ Conversion of Creatinine to creatine ○ First enzyme used for analysis

Creatininase

ENZYMATIC METHODS Lacks sensitivity and not used widely

Creatininase-CK

ENZYMATIC METHODS Creatine to sarcosine and urea

Creatinase

ENZYMATIC METHODS Sarcosine is oxidized to form formaldehyde, glycine, and peroxide

Sarcosine oxidase

ENZYMATIC METHODS ○ Measured via peroxidase reaction ○ Peroxidase reaction will produce water and oxygen

Peroxidase

ENZYMATIC METHODS ○ The oxygen released is used to oxidize the indicator (colorless substrate) ○ Once the indicator is oxidized, it will form a colored product

Peroxidase

ENZYMATIC METHODS ● As NAD+ is produced, it is measured as a decrease in absorbance ● Reduction in NADH is the one being measured

Creatininase-CK

ENZYMATIC METHODS Decrease in the absorbance is proportional to the level of creatinine in the sample

Creatininase-CK

● Accepted reference method ● Highly specific

Isotope Dilution Mass Spectrometry

● Detects characteristic fragment following ionization ● Quantifies creatinine using isotopically labeled compound

Isotope Dilution Mass Spectrometry

Specimens used

plasma, serum, or urine

T/F: Fasting is not required

T

T/F: High protein ingestion may transiently elevate serum concentration, it is significant to increase creatinine level

F; not significant

T/F: Hemolysis, lipemia, and icteric samples should be avoided

T

T/F: If samples cannot be processed immediately, it can be refrigerated

T

T/F: Samples that are not processed for more than 4 days or within 4 days can be freezed

T

Creatinine Reagent Kit R1

Picric Acid

Creatinine Reagent Kit R2

Sodium hydroxide, disodium phosphate

Standard Creatinine

2 mg/dl or 176.8 mmol/L

Ratio of R1 & R2

1:1

Set up the spectrophotometer at ___ nm

520

ASSAY REQUIREMENTS ● Wavelength: ● Optical path: ● Temperature: ● Read against _______ _____ (the blank used)

520 nm 1 cm 37 C distilled water

Feed the solution in the machine at __ seconds, read and record absorbance as A1

10

Continue the timer and at exactly ___ seconds, read and record again the absorbance as A2

120

T/F: With regards to creatinine concentration, it is very dependent by body mass

T

Computed to determine the glomerular filtration rate

Creatinine Clearance

Usually used to estimate the capacity of glomerulus to filter substances in the plasma

Creatinine Clearance

Used to approximate glomerular filtration rate (GFR)

Creatinine Clearance

Things that you should consider for the determination of ___________ is ○ the analyte should be or almost 100% is excreted in the urine ○ it should be endogenously produced by the body

glomerular filtration rate

Among all of our analytes, _______ is the best candidate for approximation of the glomerular filtration rate – called the creatinine clearance

creatinine

Measure of the amount of creatinine eliminated from the blood by the kidneys

Creatinine Clearance

Male Creatinine Clearance

97-137 mL/min

Creatinine clearance unit

mL/min

Female Creatinine Clearance

88-128 mL/min

CLINICAL SIGNIFICANCE Impaired renal function

Increased

CLINICAL SIGNIFICANCE Acute kidney injury

Increased

CLINICAL SIGNIFICANCE Low muscle mass

Decreased

CLINICAL SIGNIFICANCE Chronic kidney disease

Increased

Jaffe Plasma Reference Range Female Adult

0.6 - 1.1 mg/dL / 53 - 97 umol/L

CLINICAL SIGNIFICANCE Undernutrition

Decreased

CLINICAL SIGNIFICANCE Muscle wasting

Decreased

CLINICAL SIGNIFICANCE Muscular dystrophies

Decreased

Jaffe Plasma Reference Range Male Adult

0.9 - 1.3 mg/dL / 80 - 115 umol/L

Jaffe Plasma Reference Range Child

0.3 - 0.7 mg/dL / 27 - 62 umol/L

Jaffe 24 h Urine Reference Range Male

800-2000 mg/day / 7.1 - 17.7 mmol/day

Jaffe 24 h Urine Reference Range Female

600 - 1800 mg/day / 5.3 - 15.9 mmol/day

Enzymatic Plasma Reference Range Male Adult

0.67 - 1.1 mg/dL / 53 - 97 umol/L

Enzymatic Plasma Reference Range Female Adult

0.5 - 0.8 mg/dL / 44 - 71 umol/L

Enzymatic Plasma Reference Range Child

0.0 - 0.6 mg/dL / 0 - 53 umol/L

Considered as the best overall indicator of the level of kidney function

GFR

Gauged by measuring excretion of substance that is only minimally reabsorbed and secreted by the renal tubules

GFR

↑ creatine, ↑ urinary creatinine, _ plasma creatinine: ○ Muscle diseases ○ Muscular dystrophy ○ Poliomyelitis, ○ Hyperthyroidism ○ Trauma

N

most widely used marker for GFR, SINCE: ○ Produced at a constant rate ○ Not bound to protein ○ Not reabsorbed by the renal tubules ○ Only small amount is secreted by the tubules (10%)

Creatinine

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE Impaired renal function

Increased Serum Creatinine

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE Chronic Nephritis

Increased Serum Creatinine

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE Congestive heart failure

Increased Serum Creatinine & Decreased Creatinine Clearance

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE High cardiac output

Increased Creatinine Clearance

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE Decreased muscle mass

Decreased Serum Creatinine

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE Advanced and severe liver disease

Decreased Serum Creatinine

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE Pregnancy

Decreased Serum Creatinine & Increased Creatinine Clearance

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE Burns

Increased Creatinine Clearance

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE Carbon monoxide poisoning

Increased Creatinine Clearance

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE Impaired kidney function

Decreased Creatinine Clearance

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE Shock, dehydration

Decreased Creatinine Clearance

CLINICAL SIGNIFICANCE: SERUM / CREATININE CLEARANCE Hemorrhage

Decreased Creatinine Clearance