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False-positive elevation of creatine kinase MB mass concentrations caused by macromolecules in a patient who underwent nephrectomy for renal cell carcinoma.

Kim S, Um TH, Cho CR, Jeon JS - Ann Lab Med (2014)

View Article: PubMed Central - PubMed

Affiliation: Department of Laboratory Medicine, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea.

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Creatine kinase MB isoform (CK-MB) is a biochemical marker that is used to evaluate patients with suspected acute myocardial infarction... Rapid immunoassays to measure CK-MB mass concentration use various monoclonal anti-CK-MB antibodies, and these have been reported to be highly sensitive, specific, and free of interference... During the week following admission, the patient's CK-MB mass concentration using CK-MB VIDAS test (Vidas-Biomerieux, Marcy-I'Etoile, France) increased to more than 300 µg/L... With sample dilutions, the results were not linear... CK electrophoresis with a SPIFE CK Vis Isoenzyme Kit (Helena Laboratories, Beaumont, TX, USA) revealed only a creatine kinase MM isoform (CK-MM) band. 98.3% of the CK-MB mass concentration was decreased by polyethylene glycol (PEG) precipitation... These results raised the possibility of the presence of macro-CK... It is particularly important to distinguish macro-CK from CK-MB to avoid unnecessary invasive procedures in patients with symptoms mimicking acute coronary syndrome... Thus, macroenzyme forms should be considered when the CK-MB result does not correspond with other cardiac markers or dilution test results, even when a mass assay is performed... In our case, electrophoresis did not reveal any specific macro-CK band... The lack of GFC was a limitation in our study... In our case, the discrepancy of results between two reagents would be explained by the specificity of the antibodies used in each assay format... The macromolecule can interfere with CK-MB activity and the mass assay, causing false-positive results... Laboratory staff should always consider the possibility of the presence of macroenzyme forms in the following cases: 1) when a clinical feature does not correspond to the laboratory data, 2) when other cardiac markers such as troponin I do not correspond to the CK-MB results, and 3) when diluted samples do not produce linear results.

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Biochemical results of the patient. CK-MB mass concentrations and CK activity increased at three days after the surgery. However, troponin I level were normal, and the results of the transthoracic echocardiogram and cardiac angiography were unremarkable. During the week following admission, the patient's CK-MB mass concentration using CK-MB VIDAS test (Vidas-Biomerieux, Marcy-I'Etoile, France) increased to more than 300 µg/L, but the CK-MB mass concentrations with sample dilutions were not linear. 98.3% of the CK-MB mass concentration decreased by PEG precipitation. CK-MB mass concentrations using another immunoenzymatic reagent (Elecsys Creatine Kinase MB, Roche Diagnostics, GmbH, Mannheim, Germany) was within reference range.Abbreviations: CK, creatine kinase; CK-MB, creatine kinase MB isoenzyme; HBT, heterophilic blocking tube; PEG, polyethylene glycol.
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Figure 1: Biochemical results of the patient. CK-MB mass concentrations and CK activity increased at three days after the surgery. However, troponin I level were normal, and the results of the transthoracic echocardiogram and cardiac angiography were unremarkable. During the week following admission, the patient's CK-MB mass concentration using CK-MB VIDAS test (Vidas-Biomerieux, Marcy-I'Etoile, France) increased to more than 300 µg/L, but the CK-MB mass concentrations with sample dilutions were not linear. 98.3% of the CK-MB mass concentration decreased by PEG precipitation. CK-MB mass concentrations using another immunoenzymatic reagent (Elecsys Creatine Kinase MB, Roche Diagnostics, GmbH, Mannheim, Germany) was within reference range.Abbreviations: CK, creatine kinase; CK-MB, creatine kinase MB isoenzyme; HBT, heterophilic blocking tube; PEG, polyethylene glycol.

Mentions: Here, we report the first case of a false-positive CK-MB result (as determined by a mass assay) from a patient who underwent nephrectomy for renal cell carcinoma. A 78-yr-old man was admitted to the Urology department of Ilsan Paik Hospital in Goyang, Korea, for partial nephrectomy for the treatment of renal cell carcinoma. He developed dyspnea and tachycardia at three days after the surgery. The electrocardiogram revealed atrial fibrillation. CK-MB mass concentrations, CK activity, and N-terminal B-type natriuretic peptide (NT-pro-BNP) levels increased to 10.44 µg/L (reference range, <6.8 µg/L), 1,533 U/L (<171 U/L), and 15,927 ng/L (526 ng/L), respectively. However, the troponin I level was normal (Fig. 1). Acute myocardial infarction was suspected because CK-MB mass concentrations were increased; however, the results of the transthoracic echocardiogram and cardiac angiography were unremarkable.


False-positive elevation of creatine kinase MB mass concentrations caused by macromolecules in a patient who underwent nephrectomy for renal cell carcinoma.

Kim S, Um TH, Cho CR, Jeon JS - Ann Lab Med (2014)

Biochemical results of the patient. CK-MB mass concentrations and CK activity increased at three days after the surgery. However, troponin I level were normal, and the results of the transthoracic echocardiogram and cardiac angiography were unremarkable. During the week following admission, the patient's CK-MB mass concentration using CK-MB VIDAS test (Vidas-Biomerieux, Marcy-I'Etoile, France) increased to more than 300 µg/L, but the CK-MB mass concentrations with sample dilutions were not linear. 98.3% of the CK-MB mass concentration decreased by PEG precipitation. CK-MB mass concentrations using another immunoenzymatic reagent (Elecsys Creatine Kinase MB, Roche Diagnostics, GmbH, Mannheim, Germany) was within reference range.Abbreviations: CK, creatine kinase; CK-MB, creatine kinase MB isoenzyme; HBT, heterophilic blocking tube; PEG, polyethylene glycol.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4151014&req=5

Figure 1: Biochemical results of the patient. CK-MB mass concentrations and CK activity increased at three days after the surgery. However, troponin I level were normal, and the results of the transthoracic echocardiogram and cardiac angiography were unremarkable. During the week following admission, the patient's CK-MB mass concentration using CK-MB VIDAS test (Vidas-Biomerieux, Marcy-I'Etoile, France) increased to more than 300 µg/L, but the CK-MB mass concentrations with sample dilutions were not linear. 98.3% of the CK-MB mass concentration decreased by PEG precipitation. CK-MB mass concentrations using another immunoenzymatic reagent (Elecsys Creatine Kinase MB, Roche Diagnostics, GmbH, Mannheim, Germany) was within reference range.Abbreviations: CK, creatine kinase; CK-MB, creatine kinase MB isoenzyme; HBT, heterophilic blocking tube; PEG, polyethylene glycol.
Mentions: Here, we report the first case of a false-positive CK-MB result (as determined by a mass assay) from a patient who underwent nephrectomy for renal cell carcinoma. A 78-yr-old man was admitted to the Urology department of Ilsan Paik Hospital in Goyang, Korea, for partial nephrectomy for the treatment of renal cell carcinoma. He developed dyspnea and tachycardia at three days after the surgery. The electrocardiogram revealed atrial fibrillation. CK-MB mass concentrations, CK activity, and N-terminal B-type natriuretic peptide (NT-pro-BNP) levels increased to 10.44 µg/L (reference range, <6.8 µg/L), 1,533 U/L (<171 U/L), and 15,927 ng/L (526 ng/L), respectively. However, the troponin I level was normal (Fig. 1). Acute myocardial infarction was suspected because CK-MB mass concentrations were increased; however, the results of the transthoracic echocardiogram and cardiac angiography were unremarkable.

View Article: PubMed Central - PubMed

Affiliation: Department of Laboratory Medicine, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

Creatine kinase MB isoform (CK-MB) is a biochemical marker that is used to evaluate patients with suspected acute myocardial infarction... Rapid immunoassays to measure CK-MB mass concentration use various monoclonal anti-CK-MB antibodies, and these have been reported to be highly sensitive, specific, and free of interference... During the week following admission, the patient's CK-MB mass concentration using CK-MB VIDAS test (Vidas-Biomerieux, Marcy-I'Etoile, France) increased to more than 300 µg/L... With sample dilutions, the results were not linear... CK electrophoresis with a SPIFE CK Vis Isoenzyme Kit (Helena Laboratories, Beaumont, TX, USA) revealed only a creatine kinase MM isoform (CK-MM) band. 98.3% of the CK-MB mass concentration was decreased by polyethylene glycol (PEG) precipitation... These results raised the possibility of the presence of macro-CK... It is particularly important to distinguish macro-CK from CK-MB to avoid unnecessary invasive procedures in patients with symptoms mimicking acute coronary syndrome... Thus, macroenzyme forms should be considered when the CK-MB result does not correspond with other cardiac markers or dilution test results, even when a mass assay is performed... In our case, electrophoresis did not reveal any specific macro-CK band... The lack of GFC was a limitation in our study... In our case, the discrepancy of results between two reagents would be explained by the specificity of the antibodies used in each assay format... The macromolecule can interfere with CK-MB activity and the mass assay, causing false-positive results... Laboratory staff should always consider the possibility of the presence of macroenzyme forms in the following cases: 1) when a clinical feature does not correspond to the laboratory data, 2) when other cardiac markers such as troponin I do not correspond to the CK-MB results, and 3) when diluted samples do not produce linear results.

Show MeSH
Related in: MedlinePlus