- Red or tiger top tube
- 5-7 mL of venous blood
Additional information
- Send the sample immediately to the lab as CK activity diminishes significantly after 2 hrs at room temperature
- For evaluation of coronary syndromes, common regimens include cardiac enzymes, which include CK and CK-MB fraction every 6 hours x 3 specimens
- Make a note if the patient has been receiving multiple IM injections
- Sample to be drawn before giving IM injections or 1 hr after
Overview of Cardiac Enzymes
- Cardiac troponins (T and I) are specific markers of myocardial damage.
- Each medical facility usually utilizes one of these troponins (T or I) in conjunction with CK and CK-MB testing as part of their cardiac enzyme order set.
- It is typical to order a baseline, 6 hr and 12 hr level of a cardiac specific troponin, CK and CK-MB.
Information on CK testing
- Creatine kinase (CK) is an enzyme found in skeletal & cardiac muscle fibers, and in smaller amounts in the brain
- CK is released into the bloodstream when there is damage to tissues containing CK
- CK functions in intracellular storage and energy release
- CK primarily consists of three isoenzymes:
- Brain: CK-BB or CK1
- Cardiac: CK-MB or CK2
- Skeletal muscle: CK-MM or CK3
Creatine kinase (CK) primarily consists of 3 isoenzymes. CK-MM (Skeletal muscle) and CK-MB (Cardiac muscle) make up the majority of the total value.
The clinical utility of CK-MB includes:
- Evaluation of chest pain
- Detection and diagnosis of acute MI and reinfarction
- Assessment of severity of myocardial infarction / ischemia as the level of CK-MB correlates with degree of cardiac damage
- Assessment of the success of coronary artery reperfusion after:
- Use of thrombolytic agents
- Percutaneous transluminal angioplasty
Additional information on CK-MB
- Changes seen in CPK-MB Following Acute Myocardial Infarction
- 2-4 hours: Begins to increase
- 6-8 hours: Should be abnormally elevated
- 12-24 hours: Levels peak
- 24-72 hours: Levels start to decline
- CK-MB ratio to total CK should be elevated in order to conclude cardiac damage has occurred. A ratio of >2.6-4% of total CK being CK-MB is consistent with cardiac damage (CK-MB value should also be elevated).
The clinical utility of CK-MM includes:
- Detection of early dermatomyositis and musculoskeletal disorders that do not have neurologic basis e.g., Duchenne's muscular dystrophy (CK-MM)
- Differentiation between malignant hyperthermia and postoperative infection
- Differential diagnosis of muscular dystrophies versus congenital myopathies
The clinical utility of CK-BB includes:
- Elevation may indicate damage to tissue containing CK-BB
- May be abnormal with various cancers (bladder, breast, ovary, prostate, colon, GI carcinomas, small-cell carcinoma of lung)
Additional information
- Healthy African Americans have higher CK levels than do Caucasians and Hispanics
- Normal values are found in myasthenia gravis and multiple sclerosis
- Related laboratory tests include:
- Aspartate aminotransferase
- B-type natriuretic peptide
- Lactate dehydrogenase and isoenzymes
- Myoglobin
- Troponin
Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.
| Total CK | Conv. Units (U/L) | SI Units (µkat/L) |
|---|---|---|
| Men | 25-195 | 0.42-3.31 |
| Women | 26-170 | 0.44-2.89 |
Isoenzymes (in % of the total CK)
- CK-MM: 94-100%
- CK-MB: <4-6%
- CK-BB: 0%
| Total CK-MB | Conv. Units (U/L) | SI Units (µkat/L) |
|---|---|---|
| Normal | <10 | 0.17 |
| Borderline | 10-25 | 0.17-0.42 |
| Infarct | >25 | >0.42 |
- Infants 2 months or older usually have same normal ranges as adults
- Infants are often 2-3 times the adult value
- Newborns may be up to 10 times the adult value
Pitfalls:
- The CK-MB to total CK ratio is only useful when BOTH the CK-MB and total CK levels are elevated
- Rarely, very small infarcts may not result in significant elevations of CK-MB (however the troponin will be positive)
- Be aware that initial cardiac markers such as CK-MB cannot be relied upon to rule out acute coronary syndrome; actual cardiac muscle damage must occur and then sufficient time for blood levels of CK-MB must pass (90% sensitive by 6-8 hours after symptom onset)
- When the CK-MB is elevated but the troponin remains negative; this is usually due to a false positive result
Conditions and procedures associated with elevated total CK levels, include:
- Damage to cardiac muscles:
- Acute MI
- After open heart surgery
- Cardiomyopathy
- Cardiac contusion
- Cardiac defibrillation
- Cardiopulmonary resuscitation
- Myocarditis
- Other conditions:
- Acute psychosis
- Alcoholism (Chronic)
- Amyotrophic lateral sclerosis
- Carbon monoxide poisoning
- Charcot-Marie-Tooth disease
- CNS trauma, hemorrhage or stroke
- Delirium tremens
- Dermatomyositis
- Duchenne's muscular dystrophy
- Electric shock
- Electromyography
- Eosinophilia-myalgia syndrome
- Hypokalemia
- Hypothermia
- Hypothyroidism
- Late pregnancy & intrapartum
- Malignant hyperthermia
- Neoplasms
- Bladder
- GI tract
- Prostate
- Polymyositis
- Progressive muscular dystrophy
- Reye's syndrome
- Rhabdomyolysis
- Seizure
- Spinal muscular atrophy
- Drugs that elevate the CK level include:
- 5-fluorouracil
- Aminocaproic acid (overdose)
- Amphetamines
- Amphotericin B
- Ampicillin (IM injection)
- Analgesics (IM injection)
- Atorvastatin
- Azithromycin
- Candesartan
- Carbenicillin
- Carteolol
- Cefotaxime
- Ceftizoxime
- Cerivastatin
- Chlordane
- Chlorpromazine
- Chlorthalidone
- Cholestyramine
- Clindamycin
- Clofibrate
- Clonidine
- Clozapine
- Cocaine
- Danazol
- Dantrolene
- Diclofenac
- Didanosine
- Digoxin
- Diltiazem
- Diuretics (IM injection)
- Donepezil
- Ethchlorvynol
- Etidocaine
- Etretinate
- Fenofibrate
- Fluvastatin
- Foscarnet
- Ganciclovir
- Gemfibrozil
- Haloperidol
- Halothane
- Insulin
- Interleukin
- Isotretinoin
- Itraconazole
- Labetalol
- Lamivudine
- Levamisole
- Lidocaine
- Lithium
- Lovastatin
- Loxapine
- Meperidine
- Narcotics (IM injections)
- Nelfinavir
- Niacin
- Nifedipine
- Olanzapine
- Oral contraceptives
- Paroxetine
- Penicillamine
- Penicillin
- Phenelzine
- Phenothiazines
- Phenytoin
- Pindolol
- Pioglitazone
- Pramipexole
- Pravastatin
- Probucol
- Promethazine
- Propranolol
- Quinidine
- Risperidone
- Ritonavir
- Simvastatin
- Sirolimus
- Statins (HMG-CoA reductase inhibitors)
- Streptokinase
- Succinylcholine
- Tolcapone
- Trimethoprim
- Troglitazone
- Tubocurarine
- Vasopressin
- Zalcitabine
- Zidovudine
Conditions associated with elevated CK-MB isoenzyme, include:
- Myocardial infarction
- Acute coronary syndrome
- Cardiomyopathy
- Myocarditis
- Pericarditis (w/ myocardial involvement)
- CO poisoning
- Circulatory failure and shock
- Duchenne's muscular dystrophy
- Hypothyroidism
- Macro-CPK
- Malignant hyperthermia
- Myoglobulinemia
- Polymyositis
- Prostatic cryosurgery
- Renal failure (Chronic)
- Reye's syndrome
- Rocky Mountain spotted fever
- Skeletal muscle trauma
- Subarachnoid hemorrhage
- Surgery (Postoperative)
Conditions associated with elevated MB-BB isoenzyme, include:
- Biliary atresia
- Bowel infarction
- Brain injury
- Hypothermia
- Malignancies of:
- Bladder
- Breast
- Colon
- GI carcinomas
- Lung (Small-cell)
- Ovary
- Prostate
- Testes
- Uterus
- Newborns
- Neurosurgery
- Post CABG
- Renal dialysis patients
- Reye's syndrome
- Severe shock syndrome
- Uterine trauma
Other General Notes:
1. CK-MM isoenzyme (skeletal muscle) is elevated in most conditions in which total CK is elevated
2. Conditions associated with elevated total CPK levels, but most typically with normal CK-MB levels, include:
- Cerebrovascular accident
- Exercise
- IM injections
- Pericarditis
- Pneumonia
- Pulmonary embolism
- Seizures
Conditions with decreased CPK and its isoenzymes include:
- Low muscular mass (e.g. elderly, frail)
- Small stature
- Sedentary lifestyle
- Drugs
- Acetylsalicylic acid
- Amikacin
- Ascorbic acid
- Dantrolene
- Phenothiazines
- Pindolol
- Prednisone
- Statins
- Ulfamethoxazole
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