Creatinfosphokinase (CPK): what is it, normal values ​​and what does it change

La creatinfosfoquinasa, known by its acronym CPK, is an enzyme that acts mainly in the muscular tissues, in the brain and in the heart, being requested its measurement to investigate possible damages in these organs.

The doctor can request this exam when the person arrives at the hospital who has pain in the pecho or to verify if there are signs of a cerebrovascular accident or any illness that affects the muscles, for example.

normal values

The normal values ​​of creatinphokinase (CPK) are between 32 and 294 U/L for men and 33 to 211 U/L for women but they can vary depending on the laboratory where the examination is carried out.

what is it for

The creatine phosphokinase (CPK) exam is useful to help in the diagnosis of diseases such as infarction, renal or pulmonary insufficiency, among others. This enzyme is divided into three types according to its location:

• CPK 1 or BB: It can be found in the lungs and in the brain, mainly;
• CPK2 or MB: It is found in the heart muscle and therefore can be used as an indicator of infarction, for example;
• CPK3 or MM: It is present in the muscle tissue and represents 95% of all creatine phosphokinase (BB and MB).

The measurement of each type of CK is carried out using different laboratory methods according to their properties and according to the medical indication. When CPK measurement is requested to evaluate infarctions, for example, it is denoted as CPK MB in addition to measuring other cardiac markers such as myoglobin and troponin, mainly. Know more about normal troponin values.

A CK MB value equal to or less than 5 ng/mL is considered normal and its concentration is normally elevated in cases of infarction. The levels of CK MB only increase 3 to 5 hours after an infarction, reaching a peak in a maximum of 24 hours, normalizing its value after 48 to 72 hours after the infarction. Although it is considered a good cardiac indicator, to diagnose an infarction, the CK MB must be measured together with troponin, since the troponin values ​​return to normal 10 days after the infarction, being much more specific for the diagnosis.

What does high and low CPK mean?

The increase or decrease in the concentration of the creatinphosphokinase enzyme will depend on the type of CPK that is measured, indicating:

To perform the CPK measurement it is not mandatory that the person is in a day, although it may be recommended by the doctor, however, it is important to avoid performing strenuous physical exercises for at least 2 days before performing the exam, as this enzyme can be elevated after the physical activity due to which the muscles produce it, in addition to this, it is necessary to suspend the intake of medications such as Amphotericin B and Clofibrato, which can interfere with the result of the exam.

If the examination is requested with the aim of diagnosing the infarction, it is recommended that the relationship between CPK MB and CPK be evaluated using the following formula: 100% x (CK MB/total CK). If the result of this ratio is greater than 6%, it means that there are injuries to the heart muscle, but if the result is less than 6%, it is a sign of injuries to the skeletal muscle, for what the doctor owes investigate what is the cause.