Creatine kinase (CK) is a dimeric enzyme that has got four different forms. They are CK-MB (mostly present in the heart muscles), CK-BB ( mostly present in the brain), CK-MM (mostly present in the muscles), and mitochondrial isoenzymes.
An indication of CK-MB in the blood can be an indication of various diseases such as acute myocardial infarction, stroke, rhabdomyolysis, etc. In the onset of these diseases, CK-MB will be detected in the blood after 3-8 hours. It can stay in the blood for a long period of time. The time when a blood sample from the patient is measured can alter the value of CK-MB to some extent.
Normal range (approximate value) of CK-MB
- More than 24 U/L
Handling of CK-MB reagents
- Wear an apron and surgical gloves before carrying out the measurement.
- Look for the expiry date of the reagents during purchase and measurement time. Suppliers tend to give you reagent kits with a low expiry interval.
- Once you open the reagent bottles, the lifespan will decrease. So, look in your reagent kit literature for that.
- Bring the reagents and samples to room temperature before you can carry out any measurement.
- Always store reagents in the refrigerator when not in use.
Working principle (immunoinhibition method)
1. Principle reaction
CK-M antibody inhibits the CK-M fraction of CK-MM and CK-MB activity (the main part of the total CK activity). Then only the CK-B portion is measured. Then CK-MB is calculated by multiplying the value of CK-B activity by 2.
2. Sample Preparation
The table shown below for CK-MB measurement is valid for tulip, accurex, analyticon, and diasys. So, if you have the reagent kit of any other company, then there can be minor fluctuation in the method.
If you have two reagents, then make a working solution out of them. The ratio of their composition will be given in the literature of your reagent kit or the reagent bottle. Else, a single reagent can also be found based on the company. In that case, that single reagent kit will act as a working solution for you.
If you need to do any external incubation, then you can use an incubator or dry bath. Also, if you need to make a reagent blank then, replace the sample/calibrator with the same volume of distilled water and mix with the working reagent.
Always remember that sipping volume < sample volume + reagent volume. So that means, make sufficient sample volume to feed into the semi-auto biochemistry analyzer. Else, it will suck up the air and will give the fault reading.
If the concentration of CK-MB is too high (out of range/ non-linear), then dilute the sample with 0.9% NaCl or distilled water at the ratio of 1:y. Finally, when you get the result, multiply the value with the dilution factor (1+y).