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HelpTest ID CKELR Creatine Kinase Isoenzyme Reflex, Serum
Useful For
Detection of macro forms of creatine kinase
Diagnosing skeletal muscle disease, in conjunction with aldolase
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 <100 U/L testing is complete. CK isoenzyme electrophoresis (CKE) testing will not be performed. If the total CK activity is ≥100 U/L, CK isoenzyme electrophoresis (CKE) will be performed at an additional charge.
Method Name
CK: Photometric, Creatine Phosphate + ADP
CKE: Electrophoresis, Densitometry
Reporting Name
Creatine Kinase Isoenzyme Reflex, SSpecimen Type
SerumContainer/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.
Additional Information:
1. Patient's age and sex are required.
2. CK isoenzyme electrophoresis determinations are done if the CK, total is ≥100 U/L.
3. Include date and time of draw.
Specimen Minimum Volume
0.75 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 7 days |
| Frozen | 28 days |
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.
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.
Reference Values
CREATINE KINASE, TOTAL
Males
6-11 years: 150-499 U/L
12-17 years: 94-499 U/L
≥18 years: 52-336 U/L
Females
6-7 years: 134-391 U/L
8-14 years: 91-391 U/L
15-17 years: 53-269 U/L
≥18 years: 38-176 U/L
Reference values have not been established for patients that are less than 6 years of age.
Note: Strenuous exercise or intramuscular injections may cause transient elevation of CK.
CREATINE KINASE ISOENZYMES
MM: 100%
MB: 0%
BB: 0%
Cautions
In some patients, the presence of MB is method dependent.
Creatine kinase (CK)-MB values that exceed 50% of the total CK probably reflect unusual B subunit synthesis since heart muscle rarely exceeds 30% MB.
Day(s) Performed
CK, total: Monday through Sunday; Continuously
CK isoenzymes: Wednesday, Friday; 12 p.m.
Report Available
1 day-CK Total; 4 days- CK IsoenzymesPerforming Laboratory
Mayo Medical Laboratories in Rochester
CPT Code Information
82550-CK, total
82552-CK isoenzymes (If appropriate)