Enzymes and Cardiac Assessment
Card Set Information
Enzymes and Cardiac Assessment
Measuring Enzyme Activity Specific Enzymes Clinical Interest
Measuring Enzyme Activity and Specific Enzymes of Clinical Interest
How are enzyme reactions performed (with substrate in excess)?
What are the 2 test methods used to measure enzyme reactions?
What test methodology is a type of reaction that combines reactants, stops the reaction at a fixed time, then measures the product formed?
What test methodology is a type of reaction that combines reactants, then measures the change in absorbance at specific interfals over a specific time period?
How are enzymes reported and why are they reported that way?
Reported in activity units (because they are measured based on their activity instead of their concentration)
What is the quantity of enzyme that catalyzes the reaction of one micromole of substrate per minute under specified conditions?
International units (IU or U)
Where are the highest concentrations of lactate dehydrongenase (LD) located?
Lesser amounts in other tissues
What do LD isoenzymes consist of?
(polypeptide chains) - derived from 2 types of polypeptides designated
What clinical conditions is associated with elevated LD values?
Cardiac disorders (acute myocardial infarction)
Hepatic disease (viral hepatitis, cirrhosis, infectious mononucleosis)
Skeletal muscle diseases
Hemolytic and hematologic disorders (pernicious anemia exhibits extreme elvations of LD)
Neoplastic disorders (acute lymphoblastic leukemia)
In AMI, how do the levels of LD rise and fall?
Rise within 8-12 hours
Peak at 24-48 hours
Return to normal in 7-10 days
Not used to diagnose AMI
Useful when assessing concurrent liver damage
What is the reference rang of LD?
at 37 degrees celcius
Where are the highest concentrations of Creatine kinase (CK) and CK Isoenzymes located?
What do the CK isoenzymes consist of?
What is the clinical significance of an increase in CK-MB?
Heart muscle damage
Indicative of AMI (when used in conjunction with other markers)
Skeletal muscle damage
What is the clinical significance of an increase of CK-MM?
Skeletal muscle disorder
Heart muscle disorder
What is the clinical significance of and increase in CK-BB?
Tumors of various organs, including the prostate gland
What is the clinical significance of an increase of CK?
Cardiac disorders (AMI)
Skeletal muscle disorders (muscular dystrophy)
CNS disorders (seizures and cerebral vascular accidents)
When do the CK-MB values rise and fall following AMI?
Rise within 4-6 hours
Peak 12-24 hours
Return to normal at 2-3 days
What is the reference range of CK?
: 15-160 U/L
: 15-130 U/L
What is the reference range of CK-MB?
<6% of CK value
: 0-5 ng/mL
Where are the highest concentrations of Aspartate aminotransferase (AST) located?
Lesser ammounts in kidney and other tissues (including erythrocytes)
What clinical conditions are associated with AST?
Skeletal muscle disorders
What is the reference range for AST?
Where are the highest concentrations of alanine aminotransferase (ALT) located?
Lesser amounts in other tissues (kidneys and erythrocytes)
What clinical conditions are associated with ALT?
What is more specific indicator of liver disease, AST or ALT?
What is the reference range for ALT?
Where are the highest concentrations of alkaline phophatase (ALP) located?
What is the clinical significance of increased ALP?
Healing bone fractures
In hepatobiliary disorders that are caused by obstructive diseases, what lab would be more increased, AST, ALT, or ALP?
What causes a decrease of ALP levels?
Hypophophatasia (lack of ALP bone isoenzyme) - characterized by insufficient bone calcification
What is the reference range of ALP?
: 50-115 U/L
Children (4-15 yrs)
: 54-369 U/L
Where are the highest concentrations of Acid phosphatase (ACP) located?
Lesser amounts in bone, liver, spleen, erythrocytes, plts
What causes an increase of acid phosphatase (ACP)?
Benign prostatic hypertrophy
Breast cancer with bone metastases
Idiopathic thrombocytopenic purpura
What are the reference ranges of acid phosphatase (ACP)?
Total ACP Male
: 2.5-11.7 U/L
Total ACP Female
: 0.3-9.2 U/L
Prostatic ACP Male
: 0.2-5.0 U/L
Prostatic ACP Female
: 0.0-0.8 U/L
Where are the highest concentrations of gamma-glutamyltransferase (GGT) located?
found in Skeletal muscle or bone
What causes an increase of GGT?
Intra- and posthepatic biliary tract obstruction
Induced by drugs and alcohol
What is the reference range of GGT?
: up to 55 U/L
: up to 38 U/L
Where is amylase found?
What causes an increase of amylase?
Perforated peptic ulcer
Ruptured ectopic pregnancy
Where is lipase found?
Lesser amounts in gastric mucosa, intestinal mucosa, adipose tissue
What causes an increase of lipase?
Perforated peptic ulcer
What is the reference range for lipase?
Up to 38 U/L
Where is True cholinesterase found?
Gray matter of the brain
Where is pseudocholinesterase found?
White matter of brain
What causes a decrease in pseudocholinesterase?
Hepatocellular disease (due to decreased synthesis)
What is the reference range for psuedocholinesterase?
: 40-78 U/L
: 33-76 U/L
Where s glucose-6-phosphate dehydrogenase (G6PD) found?
What causes a decrease in G6PD?
Inherited as a sex-linked trait
Drug induced hemolytic anemia
What causes an increase of G6PD?
G6PD requires the analysis of a ___ ____ ____ ______
Red blood cell hemolysate
What is the reference range for G6PD?
8-14 U/g Hgb