Clinical Significance of Enzymes Flashcards
Pertinent findings in Case study
of 51 y.o JK
- overweight
- history of AMI and T2DM
- abdominal discomfort
- body malaise and bilateral throbbing headache
Enzyme that plays a role in energy production; ATP regeneration
Creatine Kinase
storage of high energy Creatine phosphate
Creatine Kinase
In contraction cycle, Creatine Phosphate use the production of ATP with?
relative constant level of muscle ATP
Creatine + ATP =
Creatine Phospate + ADP
Creatine Kinase has highest activity in?
Skeletal muscle, heart muscle and brain tissue
Myocardial Infarction, Muscle dystrophy and Rhabdomyolysis
Creatine Kinase
Creatine Kinase is considered a sensitive indicator of
AMI; Muscular Dystrophy (Duchenne)
CK isoforms
CK-MM (muscle); CK-MB (hybrid); CK-BB (brain)
20% CK activity is
CK-MB
Highest concentration of CK-BB is found
CNS (brain), GIT and uterus during pregnancyn akso urinary bladder, lungs, prostate, colon, stomach, and thyroid
What is the only tissue from which CK-MB enters the serum in significant quantities?
Myocardium
Which is more clinically significant isoform of CK?Why?
CK-MB isoenzyme - elevated levels come from cardiac tissue (CK- MM can also be found in skeletal muscle so less specific)
Percent that is a good indicator if myocardial damage
Greater or equal to 6%
Methods use for measurement in CK? (Clue: E.I.R.I)
Electrophoresis, Ion exchange chroma, radioimmunoassay, immunoinhibition methods
Can detech unsatisfactory separation and allows visualization of Adenylate Kinase
Electrophoresis in CK
Released from RBCs in hemolyzed samples and causes falsely elevated CK or CK MB
Adenylate Kinase
Sources of error in CK
Hemolysis, Light, Bedridden, Athletes
True or false: serum should be stored in a dark place because CK is inactivated by light (leading to falsely decreased values)
True
Total CK in Makes and Females
M: 46 to 171 U/L (0.8 to 2.9 ukat/L)
F: 34 to 145 U/L (0.6 to 2.4 ukat/L)
Catalyzes the interconversion of lactic and pyruvic acids
Lactate dehydrogenase
Lesser amounts of LD are found in
Lung,smooth muscle and brain
Acts as a Hydrogen donor
NAD+ (Nicotinamide adenine dinucleotide)
Diseases with highest levels of (total) LDH
Pernicious anemia, hemolytic disorders
Which enzyme can be used as a cardiac biomarker?
LDH
For LDH, AST, CK and Troponin I, which is a reliable cardiac biomarker of choice in AMI?
Troponin I
Which of the isoenzymes in LDH migrates most quickly toward anode in electrophoresis?
LD-1(HHHH)
LD Flipped Pattern
In necrosis and IV hemolysis, serum levels of LD-1 increase (greater than LD-2)
About LD-6
-migrates cathodic to LD-5
-alcoholic dehydrogenase
-patients w/ arteriosclerotic vascular failure
Hepatic clngestion due to cardiovascular disease
LD-5
Liver injury secondary to severe circulatory insufficiency
LD-6
Erythrocytes contain LDH approx.
100-150x in serum
LDH activity is _____ in serum regardless of storage temp
Unstable
Most labile isoenzyme in LDH
LD-5
Reference range of LDH
125-220 U/L
Commonly referred to as a transaminase (transfer of an amino group between aspartate and a-keto acids woth the for ation of oxaloaxetate and glutamate)
AST
End products of Aspartate and A-keto-glutarate
Oxaloacetate and Glutamate
Keto Acids formed by the reaction are ultimately oxidized by the _______ cycle to provide a source of energy (in AST)
Tricarboxylic Acid (TCA) Cycle
AST elevations are frequently seen in
Pulmonary embolism
In liver infection like viral hepatitis: levels may reach
100x the ULN
In cirrhosis: moderate levels approx
4x the ULN
AST activity is ____ in serum for 3-4 days at ref temp
Stable
Reference range of AST
5-35 U/L (0.1-0.6 ukat/L)
Old name of Alanine Aminotrasnferase
Glutamic Pyruvic Transaminase (SGPT)
Which is a more liver specific enzyme?
ALT
Half life of AST and ALT in serum
AST: 16 HOURS
ALT: 24 HOURS (elevated levels remain longer)
Which liver enzyme is relatively unaffected by hemolysis?
ALT
Activator used in Alkaline Phosphatase
MG+2
In ALP, highest concentration is found in the liver in both
Sinusoidal, and bile canalicular membranes
ALP measurement is used in the evaluation of
Hepatobiliary and bone disorders
Lithiasis
Gallstones
Impaired or absent flow of bile to the biliary tract, stagnant bile accumulate in the duct causing congestion and eventual damage to the cells
Cholestasis
Which disease has the highest elevation of ALP?
Paget’s disease (osteititis deformans)
Hypersecretion of parathryroid hormone that stimulates the osteoclasts in bone
Hyperparathyroidism
Responsible for bone resorption
Osteoclast
Descending order of electrophoresis fraction migration
Liver - bone - placental - intestinal
ALP is approximately 6x more concentrated in ____ than in _____
Erythrocytes, serum
Optimal pH of ACP reaction
5.0
Richest source of ACP
Prostate
Decrease activity of ACP is due to the
Loss of carbon dioxide from serum (resultant increase in pH)
Y-glutamyl donor
Glutathione
Higher elevations of GGT is generally observed in
Biliary duct obstruction
In hepatic parenchyma: GGT exists in
Smooth ER
GGT levels will be increased in patient receiving enzyme-inducing drugs
Warfarin, Phenobarbitol, and Phenytoin
Hemolysis does not interfere with GGT levels because the enzyme is lacking _____
Erythrocytes
Starch is made up of
Amylose and amylopectin
Alpha-Amylase attacks only
Alpha-glycosidic bonds
Ontermediate chains which contain alpha-1,6 branching linkages
Dextrins
Amylase requires ____ and ___ for its activation
Calcium and chloride
Major tissue sources of serum amylase
- Acinar cells of pancrease
2 Salivary glands
Macroamylasemia
Amylase molecule combines with immunoglobulins to form a too large complex to be filtered across the glomerulus
Effect of morphine and other opiated for
Ain relief before blood sampling in serum amylase
Falsely elevated
Sphincter of Oddi
Muscular opening which leads to the duodenum of small intestine
An enzyme that hydrolyzes the ester linkages of fats to produce alcohols and fatty acids
Lipase
Lipase concentration is found primarily in the
Pancreas
Preferred enzyme in diagnosing acute pancreatitis
Lipase
