Creatine Phosphokinase (CPK) Lab Values

Hey everyone, Abby here with nursing.com. In this lesson, we’ll talk about creatinine phosphokinase and its normal values, and when we would see an increased value or decreased value as part of the clinical picture. Let’s take a look. 

Creatinine phosphokinase abbreviated as CPK is measured to evaluate the extent of damage to muscular tissue. This is an enzyme that is secreted in all skeletal muscle, cardiac muscle, and also brain tissue. Doesn’t that just look painful? This is from compartment syndrome and after a fasciotomy. Muscle damage galore. Now, when do you think we would see this or which patients might have an increase in their CPK? We’re going to measure this if we know someone has Rhabdomyolysis. So, they may present with myoglobinuria or Coca-Cola colored urine. It’s going to be really dark colored. It’s also going to be evident in the case of trauma, especially burns there’s major, major, major tissue damage. Als,o compartment syndrome like on the previous slide, and it can even be increased in an acute MI. However, a subcategory of creatinine kinase is measured. It’s called CKMB when it’s specific for cardiac muscle. We’ll cover that in a different lesson, but it’s not used as often like we do troponin for acute MI. In sickle cell anemia because it’s so damaging when those sickled cells try to enter tissues, that also is going to increase our CPK. I included this image so that you could see the extent to where burns actually damage the tissue. If they’re deep enough, like here, that’s going to get to the muscle and that’s when the CPK is going to be released. 

In normal therapeutic values. We would see between 55 and 170 units per liter. This lab is collected in a plasma separator tube like this green tube here. Values will be increased as we mentioned with Rhabdo. It would be above a thousand micrograms per liter. Chronic muscle disease like muscular dystrophy will also see an increase in those CPK values. Trauma such as burns, crush injuries, even blast injuries, anything that’s damaging muscle, muscle, muscle muscle. And then as I mentioned, it used to be used routinely for the evaluation of myocardial infarction however, it’s more often that we see a troponin. The value will be decreased when there’s brain tissue disease. Remember we mentioned muscular tissue and also brain tissue, particularly with Alzheimer’s. It’s going to be decreased when there’s connective tissue disorders or disease like rheumatoid arthritis or lupus. It’s also going to be reduced when there’s less physical activity, because even excessive exercise can drive up our CPK because those muscles are damaged, right? So, if someone has issues with mobility, they’re not going to have that muscular strain therefore, the CPK values will actually be reduced and that’s also going to be the case in patients who are elderly that might have less mobility. 

The linchpins for this lesson or that the creatinine phosphokinase or C P K is measured to evaluate muscle and brain tissue damage. Normal values are between 55 and 170 units per liter. We’ll see an increase with major muscle damage as evident in Rhabdo, trauma, even acute MI, and sickle cell anemia. The value will be decreased mostly when we see connective tissue disorders like rheumatoid and lupus, or in brain tissue damage like Alzheimer’s. We’ll see it as well in those that are immobile, they’re not getting that muscle strain therefore the CPK is not going to be released. 

You all did great on this lesson and this wraps it up. We love you guys, now go out and be your best self today, and as always, happy nursing.

References:

• https://www.ncbi.nlm.nih.gov/books/NBK546624/
• https://medlineplus.gov/lab-tests/creatine-kinase/
• https://www.hopkinslupus.org/lupus-tests/clinical-tests/creatine-phosphokinase-cpk/
• https://www.mountsinai.org/health-library/tests/creatine-phosphokinase-test#:~:text=This%20test%20may%20be%20used,badly%20a%20muscle%20is%20damaged
• https://www.mountsinai.org/health-library/tests/creatine-phosphokinase-test#:~:text=This%20test%20may%20be%20used,badly%20a%20muscle%20is%20damaged