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Test ID: CKELR Creatine Kinase Isoenzyme Reflex, Serum

Reporting Name

Creatine Kinase Isoenzyme Reflex, S

Useful For

Detecting the macro forms of creatine kinase (CK)

 

Identifying the source of a CK elevation

Profile Information

Test ID Reporting Name Available Separately Always Performed
CK Creatine Kinase (CK), S Yes Yes
CKER CK Isoenzyme Elec, Specimen Only No Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
CKE CK Isoenzyme Electrophoresis, S No No

Testing Algorithm

Testing begins with total creatine kinase analysis (CK). If the total CK activity is below 100 U/L, testing is complete.

 

If total CK activity is 100 U/L or greater, then isoenzyme electrophoresis (CKE) will be performed at an additional charge.

Specimen Type

Serum


Advisory Information


This test is not appropriate for the detection of myocardial injury and should not be used for that purpose. For diagnosis of an acute myocardial infarction order TRPS / Troponin T, 5th Generation, Plasma.



Necessary Information


1. Patient's age and sex are required.

2. Include date and time of draw.



Specimen Required


Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 2 mL

Collection Instructions:

1. Serum gel tubes should be centrifuged within 2 hours of collection.

2. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.


Specimen Minimum Volume

0.75 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 7 days
  Frozen  28 days

Reference Values

CREATINE KINASE, TOTAL

Males

≤3 months: not established

>3 months: 39-308 U/L

Females

≤3 months: not established

>3 months: 26-192 U/L

Reference values have not been established for patients that are less than 3 months of age.

Note: Strenuous exercise or intramuscular injections may cause transient elevation of creatine kinase (CK).

 

CREATINE KINASE ISOENZYMES

MM: 100%

MB: 0%

BB: 0%

Day(s) and Time(s) Performed

CK, total: Monday through Sunday; Continuously

CK isoenzymes: Tuesday, Thursday; 12 p.m.

CPT Code Information

82550-CK, total

82552-CK isoenzymes (If appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CKELR Creatine Kinase Isoenzyme Reflex, S 2157-6

 

Result ID Test Result Name Result LOINC Value
CK Creatine Kinase (CK), S 2157-6
CKER CK Isoenzyme Elec, Specimen Only 31208-2

Clinical Information

Creatine kinase (CK) activity is found in the cytoplasm of several human tissues; major sources of CK include skeletal muscle, myocardium, and the brain. Cytoplasmic CK isoenzymes are dimers of the subunits M and B (MM, MB, or BB). Brain tissue contains predominantly CK-BB (CK1). Skeletal muscle contains almost exclusively CK-MM (CK3). The myocardium contains approximately 30% of CK-MB (CK2), which has been called the "heart-specific" isoenzyme. CK-MB is increased in acute myocardial infarction (AMI); however, CK-MB has been replaced by troponin as the preferred biomarker for the diagnosis of AMI.

 

Mitochondrial CK, located at the outer surface of the inner mitochondrial membrane, has been suggested to catalyze the rate-limiting step of energy transfer from mitochondrial adenosine triphosphate (ATP) with the formation of creatine phosphatase (CP). The CP molecule, which is smaller in size than ATP, diffuses to target organelles in the cytoplasm where its energy is transferred to ATP by cytoplasmic CK. CK activity results in nonaerobic production of ATP in muscle tissues during work.

 

Macro CK refers to at least 2 forms of CK. Macro CK type I is an antibody-bound form of cytoplasmic CK. It migrates between CK-MM and CK-MB. Macro CK type II (mitochondrial CK) migrates slightly cathodic of CK-MM. Detection of macro forms of CK is the primary reason for electrophoresis of CK activity.

Interpretation

Creatine kinase (CK)-MB appears in serum 4 to 6 hours after the onset of pain in a myocardial infarction, peaks at 18 to 24 hours, and may persist for 72 hours. 

 

CK-MB may also be elevated in cases of carbon monoxide poisoning, pulmonary embolism, hypothyroidism, crush injuries, and muscular dystrophy. 

 

Extreme elevations of CK-MB can be associated with skeletal muscle cell turnover as in polymyositis, and to a lesser degree in rhabdomyolysis, as seen in strenuous exercise, particularly in the conditioned athlete. 

 

CK-BB can be elevated in patients with head injury, in neonates, and in some cancers such as prostate cancer and small cell carcinoma of the lung. It can also be elevated in other malignancies; however, the clinical usefulness of CK-BB as a tumor marker needs further investigation. 

 

The presence of macro CK can explain an elevation of total CK. It does not rise and fall as rapidly as CK-MM and CK-MB in muscle injury. 

 

Macro CK type II (mitochondrial CK) is rarely observed. It is only seen in acutely ill patients with malignancies and other severe illnesses with a high-associated mortality, such as liver disease and hypoxic injury.

Clinical Reference

1. Apple FS, Quist HE, Doyle PJ, et al: Plasma 99th percentile reference limits for cardiac troponin and creatine kinase MB mass for use with European Society of Cardiology/American College of Cardiology consensus recommendations. Clin Chem 2003 Aug;49(8):1331-1336

2. Danese E, Montagnana M: An historical approach to the diagnostic biomarkers of acute coronary syndrome. Ann Transl Med 2016;4(10):194 doi:10.21037/atm.2016.05.19

Analytic Time

1 day-CK Total; 4 days- CK Isoenzymes

Method Name

CK: Photometric, Creatine Phosphate + ADP

CKE: Electrophoresis, Densitometry

Test Classification

This test has been cleared, approved or is exempt by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.