Creatinine Flashcards
Creatine
• Synthesized primarily in the liver from (3)
arginine, glycine, and methionine
Creatine is transported to tissues and is converted to_______, which serves as a high-energy source
phosphocreatine
EC 2.1.4.1
L-ARGININE: GLYCINE AMIDINOTRANSFERASE (AGAT)
EC 2.1.1.2
GUANIDINOACETATE METHYLTRANSFERASE (GAMT)
(GAA)
GUANIDINOACETATE
arginine»_space;> guanidoacetate
Happens in the
in kidney
guanidoacetate»_space;> creatine
Happens in the
Liver
creatine»_space;> creatine phosphate
What enzyme caused the conversion?
creatine phosphokinase
creatine phosphate»_space;> creatinine
Unsa gitanggal?
P + H2O
Creatinine»_space;> creatine phosphate
What enzyme is added?
Creatine kinase
Creatinine»_space;> ______»_space;> Glomerular filtration»_space;> _____
Plasma
Urine
• Endogenous substance
• With a MW of 113 Da
Creatinine
Creatinine
• Waste product of____ metabolism
muscle
Creatinine
Produced by the muscle from creatine and creatine phosphate thru non-enzymatic (2) process
dehydration and dephosphorylation
Disease Correlation:
^^^______
Muscle diseases
Muscular dystrophy
Poliomyelitis
Hyperthyroidism
Trauma
Creatine
Disease correlation
^^^^______
Associated with abnormal renal function
Creatinine
• Most widely used marker for GFR
Creatinine
Creatinine
Advantages:
~ Endogenous substance with constant rate of production
~ Not bound to plasma proteins
Not reabsorbed by the tubules
~ Only a small amount is secreted by the tubules
Creatinine
Disadvantages:
× Depends mainly on muscle mass
× Quantity of meat ingestion can substantially influence the total
daily production
× Method is subjected to many interferences
The Diagnostic Function of
Creatinine
If the kidneys are damaged or impaired and cannot work normally
The amount of creatinine in urine goes____ while its level in blood goes____
Creatinine has been found to be a fairly reliable indicator of kidney function.
Serum creatinine level is an important diagnostic tool to asses renal function
down; up.
How is Creatinine Used to Monitor Renal Function..?
In renal failure the kidney will not be able to excrete creatinine in urine leading to an_____ in serum creatinine level.
elevation
Is there other factors mav affect creatinine level in the blood…’
?
The amount of muscle tissue you have.
Protein in diet.
:
Measures how well creatinine is removed from blood by kidneys which reflects glomerular filtration rate (GFR)]
Creatinine Clearance Test
• Creatinine reacts with picric acid (trinitrophenol)
in alkaline solution to form a red-orange chromogen
Direct Jaffe Reaction (1886)
Direct Jaffe Reaction (1886)
• Creatinine reacts with_____
in alkaline solution to form a____ chromogen
picric acid (trinitrophenol)
red-orange
DJR
- Folin-Wu Method (1919)
- Fuller’s Earth
- Method of Hare (addition to Lloyd’s Reagent)
- Fuller’s Earth
- Method of Hare (addition to Lloyd’s Reagent)
- Folin-Wu Method (1919)
Hare (addition to Lloyd’s Reagent)
- PFF + sodium aluminum silicate
• Eluted and reacted with alkaline pirate
• Method of Hare (addition to Lloyd’s around for and in wannabee
- PFF + sodium aluminum silicate
• Eluted and reacted with alkaline pirate
• Method of Hare (addition to Lloyd’s Reagent)
Creatinine + Picric acid
Yellow color
Creatinine Picrate
Orange color
Measured at
colorimetrically
520 nm
• performed directly on sample
• serum is mixed with alkaline picrate and the rate of change in absorbance is measured
Kinetic Jaffe Reaction
• Interferences:
(2)
- a-ketoacids
- cephalosporins
Coupled-Enzymatic Method (2)
Creatininase
a. Creatininase-CK Method
b. Creatininase-Hydrogen Peroxide Method
Creatininase-CK Method
• Creatininase
• CK, PK, LDH
- NADH to NAD+ (340 nm)
Creatininase-Hydrogen Peroxide Method
• Creatininase
Creatinase
Sarcosine oxidase
Peroxidase
specimen requirement
Plasma; serum
Urine
- Hemolyzed and icteric samples should be avoided
- Lipemic samples produce erroneous results
- Fasting is not required
Plasma, serum
should be refrigerated or frozen if longer than 4 days
Urine
Creatinine in serum or urine is stable for at least__ days at___
7
4°C
interfering substances
False increase;
reacts with picrate solution
• Ascorbic Acid
• Glucose
• Protein, urea
• Alpha-keto acids/ ketones
• Cephalosporins, Dopamine, Lidocaine
false decrease
• Hemoglobin and bilirubin
• Uric acid
- Decreased in kinetic methods