|LETTER TO EDITOR
|Year : 2020 | Volume
| Issue : 3 | Page : 513-514
Creatine kinase-MB level more than total creatine kinase level: A macro creatine kinase type 2 phenomenon
Won Sriwijitalai1, Viroj Wiwanitkit2
1 RVT Medical Center, Bangkok, Thailand
2 Dr. DY Patil University, Pune, Maharashtra, India
|Date of Submission||08-Sep-2020|
|Date of Decision||15-Sep-2020|
|Date of Acceptance||27-Mar-2020|
|Date of Web Publication||1-Feb-2021|
Dr. Won Sriwijitalai
RVT Medical Center, Bangkok
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sriwijitalai W, Wiwanitkit V. Creatine kinase-MB level more than total creatine kinase level: A macro creatine kinase type 2 phenomenon. J Datta Meghe Inst Med Sci Univ 2020;15:513-4
|How to cite this URL:|
Sriwijitalai W, Wiwanitkit V. Creatine kinase-MB level more than total creatine kinase level: A macro creatine kinase type 2 phenomenon. J Datta Meghe Inst Med Sci Univ [serial online] 2020 [cited 2021 Feb 24];15:513-4. Available from: http://www.journaldmims.com/text.asp?2020/15/3/513/308545
Creatine kinase (CK) is an important enzyme. The measurement of CK is a routine laboratory investigation in the clinical laboratory. The measurement of an important CK isoenzyme, CK-MB, and total CK-MB is generally used as a cardiac marker test for acute cardiac disease., Here, the authors present an interesting case study with an aberrant laboratory result. The analysis of a blood sample of a 58-year-old female patient showed that CK-MB level was equal to 24 U/I and total CK was equal to 20 U/I. The same NAC-activated method was used in the analysis for both total CK and CK-MB tests (two different laboratory tests) in the laboratory. This patient had acute chest pain and the physician in-charge requested for CK and CK-MB test aiming at diagnosis of possible cardiac problem. The patient had no other known personal illness. Repeated analyses were performed in all laboratory tests under standard clinical chemistry laboratory quality control.
The interesting observation is the higher level of CK-MB level than the CK level. It is impossible that the CK-MB level can exceed the total CK level; therefore, the case is suspicious for a possible interference from a macroenzyme phenomenon. The explanation for this case is the macro CK phenomenon. In the measurement, the false overestimation is due to CK-BB isoenzyme. Regarding NAC-activated method for the measurement of total CK, overall of all forms of CK in the blood sample is directly measured. Regarding NAC-activated method for the measurement of CK-MB, only CK-B level is first measured, and then, the derived result is multiplied by 2 to get the final assumed CK-MB level. Therefore, in case that there is an overestimation of CK-BB, the abnormal result with CK-MB level exceeding the total CK level can be expected. The overestimation of CK-BB level might be due to several conditions, such as diseases of lung and kidney.,, This kind of phenomenon is macro CK type 2.
Liu et al. noted that the phenomenon of spuriously high CK-MB activity out of proportion to total CK is an important condition to be recognized for any cases with elevated CK-MB level despite there is no myocardial injury. A macro CK usually causes a mild elevation, usually <500 IU/L, in CK or a high CK-MB/CK ratio with a normal level of total CK. In laboratory medicine, there are two different types of macro CK, type 1 and type 2. Marco CK type 1 is resulted from immune complex phenomenon and observed in the patients with autoimmune disease. Increased total CK and CK-MB proportion is observable in macro CK type 1. Macro CK type 2 results from the existence of atypical polymeric of mitochondrial-derived CK, which is not related to an autoimmune process. The observation of CK-MB level exceeding the total CK level is a main unique clinical presentation of macro CK type 2. The patient who has macro CK type 2 might be healthy without any comorbidity.
The macro CK type 2 phenomenon is more common among female patient. In the previous study in referencing laboratory, the rate of macro CK type 2 phenomenon is up to 1.5%. Therefore, the practitioner has to recognize the possibility of false overestimation of CK-MB level in clinical practice.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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