Healthcare and Lab
Diagnostic Newsletter


Cardiac Markers:  
Troponin I/Troponin T

- Cardiac Troponins as 
  Markers of Myocardial Injury

Cardiac Markers:  
Myoglobin Test
Common Questions

CK-MB Test
Also known as: CK MB, CPK  
  Formally known as: Creatine 

Cardiac Markers:  
CK, CPK Test
   Creatinine Kinase
   ครีเอตินีน ไคเนส

Cardiac Markers:  
LD, LDH Test
    Lactate Dehydrogenase
    แลคเตส ดีไฮโดรจิเนส

 Myocardial infarction

     ( ห้องปฏิบัติการชันสูตร ) 
Reference test procedure


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  Cardiac Markers:      



The RapidCardiac Panel test is an immunochromatography based one step in vitro test. It is designed for qualitative determination of cardiac troponin I (cTnI), CK-MB and Myoglobin in human serum specimens as an aid in the diagnosis of myocardial infarction.


Cardiac troponin I (cTnI) is a cardiac muscle protein with a molecular weight of 22.5 kilodaltons. Together with troponin T (TnT) and troponin C (TnC), TnI forms a troponin complex in heart to play a fundamental role in the transmission of intracellular calcium signal actin-myosin interaction. The human cTnI has an additional amino acid residues on its N-terminal that are not exist on the skeletal forms thus making cTnI a specific marker for indicating cardiac infarction. cTnI  is released rapidly into blood after the onset of acute myocardial infarction (AMI). Its release pattern is similar to CK-MB (4-6 hours after the onset of AMI). However, CK-MB level returns to normal after 36-48 hours, while levels of cTnI remains elevated for up to 6-10 days. The level of cTnI is very low in normal healthy people, and not detected in patients with skeletal muscle injury. Therefore, cTnI is a specific marker for diagnosis of acute myocardial infarction.

Creatine kinase is a dimer occurring in various in three isoenzymic forms, depending on the particular combination of its non-identical subunits:BB(brain type);MM(skeletal type); and MB(hybrid type).  Creatine kinase-MB isoenzyme is released into circulation later than myoglubin, reaching  abnormal levels within 4 to 6 hours after onset of  symptoms,it reaches its highest level with a typical range of 39-185 ng/ml after about 18 to 24 hours,and returns to normal in about 2 to 3 days.CK-MB is widely recognized as the traditional marker for the diagnosis of AMI.

Myoglobin is a low molecular weight, cytoplasmic serum protein. Due to its low molecular weight, myoglobin is released more rapidly when muscle cells are damaged than other markers. Serum concentration of myoglobin increases above the normal range as early as 1 hour after myocardial infarction, and peak in approximately 4 to 8 hours after onset. Therefore, myoglobin is better suited for the early diagnosis of AMI.

RapidCardiac Panel test is a sandwich immunoassay. When serum sample is added to sample pad, it moves through the conjugate pad and mobilizes gold antibody conjugate that is coated on the conjugate pad. The mixture moves along the membrane by capillary action and reacts with anti-cardiac marker antibodies that is coated on the test region. If cardiac markers are present at levels of cut-off level or greater, the result is the formation of a colored band in the test region.  If there are no cardiac markers in the sample, the area will remain colorless. The sample continues to move to the control area and forms a pink to purple color, indicating the test is working and the result is valid.

Below are the cut-off concentrations for each cardiac marker using in the test.
Troponin I                       1.5 ng/ml
CK-MB                           7.0 ng/ml
Myoglobin                      100 ng/ml


Material Provided

1.       RapidCardiac Panel Test device


Materials Required but not Supplied
1.       Serum collection containers.
2.       Timer or clock


Store the test device at 2 to 30oC. Do Not Freeze.


1.       For in vitro diagnostic use only.

2.       Do not use product beyond the expiration date.

3.       Handle all specimens as potentially infectious.

Specimen Collection and preparation

1.       The serum, whole blood or plasma specimen should be collected under standard laboratory conditions.

2.       Heat inactivation of specimens, which may cause hemolysis and protein denaturation, should be avoided.

3.       Patient samples performed best when tested immediately after collection. If specimans are to be stored, the red blood cells should be removed to avoid hemolysis. If the sample cannot be                                            tested within 24 hours, serum or plasma should be frozen until the test can be performed. Whole blood samples should be refrigerated at 2–8oC in stead of being frozen. Allow sample to reach room temperature before proceeding.

4.       Sodium azide can be added as a preservative up to 0.1% without effecting the test results.



1.       The control band is an internal reagent and procedural control.  It will appear if the test has been performed correctly and the reagents are reactive.

2.       Good Laboratory Practice recommends the daily use of control materials to validate the reliability of the device. Control materials which is not provided with this test kit are commercially available.


1.       Bring all materials and specimens to room temperature.
2.       Remove the test card from the sealed foil pouch.
3.       Place the transfer pipette in the specimen and depress the bulb to withdraw a 
4.       Hold the pipette in a vertical position over the sample well of the test card   
         and    deliver 7-10 drops(300-500 ml) of serum sample or 10 – 15 drops (500 – 800 
l) of whole blood sample into the sample well.
5.       Read the result at 15 minutes.




If two colored bands are visible on any strip of the device within 15 minutes, the test result is positive and valid. The test result can be read as soon as a distinct colored band appears in the test area.

Note: Specimens containing very low levels of cardiac markers may develop two color bands over 15 minutes.


If test area has no color band and the control area displays a colored band, the result is negative and valid.

Invalid result:

If a colored band does not form in the control region of any strip, the test result is invalid. The sample must be re-tested, using a new test device.


If after 15 minutes, you see one of the following results. It may imply the indicated syndrome.

a)       MYG-positive/CKMB-positive/TPI-positive

      (MYO ≥ 100 ng/mL, CK-MB ≥ 7.0 ng/mL, Tn I ≥ 1.5ng/mL)

Myocardial cell necrosis within the past 12 hours.

b)       MYG-positive/CKMB-positive/TPI-negative

      (MYO ≥ 100 ng/mL, CK-MB ≥ 7.0 ng/mL, Tn I < 1.5ng/mL)

Early muscle or cardiac injury.  Serial Troponin I testing is suggested in 4 & 8 hrs to rule in acute coronary syndrome

c)       MYG-negative/CKMB-positive/TPI-positive 

      (MYO < l00 ng/mL, CK-MB ≥ 7.0 ng/mL, Tn I ≥ 1.5ng/mL)

Acute myocardial infarction post 12 hours from the onset of early symptoms

d)       MYG-negative/CKMB-positive/TPI-negative

      (MYO <.100 ng/mL, CK-MB ≥ 7.0 ng/mL, Tn I < 1.5ng/mL)

Early muscle or cardiac injury. Serial Troponin I testing is suggested in 4 & 8 hrs to rule in acute coronary syndrome.

e)       MYG-negative/CKMB-negative/TPI-positive

      (MYO < l00 ng/mL, CK-MB < 7.5 ng/mL, Tn I ≥ 1.5ng/mL)

Acute myocardial infarction post 24-96 hours

f)          MYG-positive/CKMB-negative/TPI-negative

      (MYO ≥ l00 ng/mL, CK-MB < 7.5 ng/mL, Tn I <    1.5ng/mL)

Early muscle or cardiac injury. Serial Troponin I testing is suggested in 4 & 8 hrs to rule in acute coronary syndrome. (MYO ≥ l00 ng/mL, CK-MB < 7.5 ng/mL, Tn I < 1.5ng/mL).

g)       MYG-positive/CKMB-negative/TPI-positive

      (MYO ≥ l00 ng/mL, CK-MB < 7.5 ng/mL, Tn I ≥ 1.5ng/mL).

A very possible myocardial cell necrosis

h)       MYG-negative/CKMB-negative/TPI-negative

      (MYO < l00 ng/mL CK-MB < 7.5 ng/mL, Tn I < 1.5 ng/ml)

Acute myocardial infarction may not happen. If the cardiac injury is suspected, retest in 2 - 4 hours.



1.       The test result should be used in conjunction with other clinical information such as clinical signs and symptoms and other test results to diagnose AMI. A negative result obtained from a patient whose sample was taken at 2-20 hours after the onset of chest pain may help in ruling out AMI. A positive result from a patient suspected of AMI may be used as a rule-in diagnosis and requires further confirmation. Serial sampling of patients suspected of AMI is also recommended due to the delay between the onset of symptoms and the release of the cardiac markers in to the bloodstream.

2.       A number of conditions, other than myocardiac infarction, including polymyositis, dermatomyositis, systemic lupus erythematosus, shock, severe renal failure, or muscle damage caused by trauma, ischemia and inflammation, can cause elevated levels of myoglobin. These conditions should be considered with appropriate clinical evidence.Recent cardioversion or an anginal episode may increase myoglobin level. Testing 12 hours or later after after onset of myocardial infarction can produce misleading results, because serum levels may already have returned to normal range.

3.       RapidCardiac Panel test only provides qualitative result. A quantitative assay method must be used to determine the concentrations of each marker.

4.       As with all diagnostic tests, a definitive clinical diagnosis should not be based on the result of a single test, but should only be made by the physician after all clinical and laboratory findings have been evaluated.



RapidCardiac Panel designed to yield a positive result for the concentrations of cTnI at 1.5 ng/ml or greater, CK-MB at 7 ng/ml or greater and myoglobin at 100 ng/ml or greater. The time required for blood cTnI level to reach the upper limit of normal has been found to be 4-6 hours after the onset of symptoms. cTnI level reaches the maximum concentration after 12-24 hours of the onset, and then remains elevated for 6-10 days in some cases. Therefore, a negative result within the first hours of the onset of symptoms does not rule out AMI with certainty. If suspected, repeat the test at appropriate intervals.

The time required for blood CK-MBI level to reach the upper limit of normal has been found to be 4-6 hours after the onset of symptoms. CK-MBI level reaches the maximum concentration after 18-24 hours of the onset, and then remains elevated for 2-3 days in some cases. Therefore, a negative result within the first 4 hours of the onset of symptoms does not rule out AMI with certainty. If suspected, repeat the test at appropriate intervals.

Normal serum myoglobin levels range from 30 to 90 ng/ml. After 1 hour of the onset of myocardial infarction, serum myoglobin level can elevate to 200 ng/ml or even higher. During the peak hour, myoglobin level can be as high as 900 ng/ml. The level of myoglobin usually returns to normal 12 hours after the onset of the myocardial infarction. Elevated myoglobin level has also been observed in patients with other diseases as mentioned in LIMITATIONS OF THE PROCEDURE.



RapidCardiac Panel test can detect cTnI in serum with concentration of 1.5 ng/ml or greater, CK-MB at 7.0 ng/ml or greater and myoglobin at 100 ng/ml or greater.



The accuracy of the RapidCardiac Panel test were evaluated in each component strips.

1.       Troponin I


Negative ( 0 ng/ml)

Tn I ( 0.3 – 0.8 ng/ml)

Tn I ( > 1.1 ng/ml)

Number of specimen
















2.       CK-MB


Negative ( 0 ng/ml)

CK-MB ( 0.8 – 6.9 ng/ml)

CK-MB ( 7.0 ng/ml)

Number of specimen

















3.       Myoglobin


Negative ( 0 ng/ml)

Myo  ( 13 – 66 ng/ml)

Tn I ( > 100 ng/ml)

Number of specimen

















Interference testing:

             The following substances were added to cardiac marker negative and cut-off level controls. No interference was found with any of the substances at the following concentrations:

                        Bilirubin                                     10 mg/dl
                        Cholesterol                               800 mg/dl
                        Hemoglobin                              250 mg/dl
                        Triglyceride                               1250 mg/dl


1.       Adams JE, et al., Circulation, Vol. 88, 101-106 (1993)
2.       Adams JE, et al., N. Eng. J. Med. Vol. 330,  670-674(1994)
3.       Bodor GS, et al., Clin. Chem.  Vol. 41, 1710-1715 (1995)
4.       Brogan GX, et al., Academic Emerg. Med.  Vol. 4, 6-12 (1997)
5.       Tucker JF, et al., Academic Emerg. Med.  Vol. 4, 13-21(1997)
6.       Larue C. et al., Clin Chem. Vol. 39: 972 (1993)
7.       Apple FS, et al.,Clin. Chem. Vol. 41: 95 (1995)
8.       Brogan GX, et al., Ann. Emerg. Med. 27: 22-28 (1996)





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