Question

1. Describe the test commonly ordered as cardiac enzymes

2. Explain the rationale for serial cardiac enzyme blood specimen collections.

3. Examine potential sources of error for chemistry testing procedures.

Answer 1

1)Describe the test commonly ordered as cardiac enzymes

Cardiac enzymes are protien found in cardiac muscle.During heart attack,it released in the bloodstream and shows an elevated level when tested.

There are three types of cardiac enzymes.

1. Troponin
2. Creatinine phosphokinase
3. Myoglobin

These are also called biomarkers.

1 Troponin : Troponin is mainly found in cardiac and skeletal muscles.There are 3 forms; they are Troponin T, Troponin I & Troponin C. Troponin T & I are cardiac specific enzymes whereas Troponin C is seen in skeletal muscle.Normal range is below 0.04 ng/ml. 0.04- 0.39 ng/ml means there is mild heart damage and above 0.40ng/ml shows likely to have myocardial infarction. If there is any heart muscle damage occurs, it elevate after 2-4 hours after the injury and remains in the blood upto 14 days.

2 Creatinine phosphokinase: CPK is a protein found in heart,brain and skeletal muscle.There are three forms ; CPK-MB(heart), CPK-MM (skeletal) and CPK-BB ( brain). When the heart muscle is injured, it releases gradually in the blood and the normal level is 10 - 120 mcg/l.

3.Myoglobin : Myoglobin is another protein found in blood when myocardial infarction occurs.It helps in muscle contraction by giving energy from the oxygen stored in High levels can be seen few hours after injury. Normal level 0-85 ng/ml.

2. Explain the rationale for serial cardiac enzyme blood specimen collections

Normally physician orders for Troponin I & CPK MB if they suspect a cardiac injury.Initially, it may be normal or mild above normal because these enzymes released into the blood stream after 2-4 hours of injury and peak of CPK-MB can be upto 2 days.Hence, doctors repeat these test in frequent intervals to confirm the injury.

3)Examine potential sources of error for chemistry testing procedures

It can be instrumental, environmental,human and analytical.