creatine metabolism
DESCRIPTION
Synthesis and degradation of creatineTRANSCRIPT
Dr. Vijay Marakala, MBBS, MD.
Senior Lecturer
BIOCHEMISTRY
IMS, MSU.
CREATINE METABOLISM
Synthesis Degradation
CREATINE SYNTHESIS
First step in KIDNEY
Second step in LIVER
CREATINE SYNTHESIS
CREATINE SYNTHESIS REQUIRES THREE AMINO ACIDS
Glycine
Arginine
Methionine
GLYCINE ARGININE
GUANIDOACETATE
ORNITHINE
Arginine-glycine Transaminidase
CREATINE
GuanidoacetoacetateMethyltransferase
S-Adenosylmethionine(SAM)
S-Adenosylhomocysteine(SAH)
In KIDNEY
In LIVER
Distribution of body creatine
From liver, transported to other tissues
98% are present in skeletal and heart muscles
In Muscle, gets converted to the high energy source creatine phosphate
Creatine to creatine
phosphate
CREATINE
CREATINE PHOSPHATE
ATP
ADP
Creatine Kinase In muscle and brain
CREATINE PHOSPHATE
Is a high-energy phosphate compound
Acts as a storage form of energy in
the muscle
The amount of creatine phosphate in the body is proportional to the muscle mass
CREATINE PHOSPHATE – STORE
OF ENERGY IN THE MUSCLE
During muscle contraction the
energy is derived from ATP
hydrolysis.
Thereafter the ATP is regenerated
by hydrolysis of creatine
phosphate
This is called LOHMANN’S
REACTION
DEGRADATION OF CREATINE
Creatine and creatine-P
spontaneously form creatinine
Formation of creatinine is
non-enzymatic
Creatinine is excreted in the
urine
The amount of creatinine excreted per day is constant and depends on body muscle mass
DEGRADATION OF CREATINE
CREATINE
CREATINE PHOSPHATE
ATP
ADP
Creatine Kinase
In muscle and brain
CREATININE
H2O
Pi
Non-enzymatic
DEGRADATION OF CREATINE
CLINICAL SIGNIFICANCE OF
CREATININE
The amount of creatinine excreted from
the body is proportional to the total
creatine phosphate content of the
body, and thus can be used to estimate
muscle mass.
Serum creatinine is a sensitive indicator
of kidney disease (Renal function test)
Serum creatinine increases with the
impairment of kidney function
SERUM CREATININE
SERUM CREATININE
Factors reducing
serum creatinine
Low muscle mass
Malnutrition
Factors increasing serum creatinine
Old age
Renal diseases
Glomerulonephritis
Pyelonephritis
Renal failure
Urinary obstruction
Congestive cardiac failure
URINE CREATININE
The normal daily excretion of creatinine
ranges from 1-2 gm.
A decrease in muscle mass due to muscular dystrophy or paralysis leads to
decreased level of creatinine in urine
Creatinine clearance test is widely used as a measure of the glomerular filtration
rate and is decreased in renal failure
URINE CREATININE
INCREASED
• Acromegaly
• Gigantism
DECREASED
• Later stage of Muscular dystrophy
CLINICAL PEARL
Decreased urinary and blood levels of creatinine indicate
diminished production of
creatinine by skeletal muscle.
However, high blood creatinine levels
could indicate an inability of the kidney
to excrete creatinine, resulting from renal disease.