Raised concentration of plasma creatine kinase BB isoenzyme in myelodysplasia

Area of Science:

• Biochemistry
• Hematology
• Cardiology

Background:

• Elevated plasma creatine kinase (CK) activity is a key indicator of myocardial infarction.
• Standard assays for CK isoenzymes, particularly CK-MB, are crucial for diagnosing cardiac events.

Observation:

• A 72-year-old woman with suspected myocardial infarction presented with elevated total CK (343 U/l) and apparent CK-MB activity (350 U/l).
• Echocardiography revealed no acute cardiac changes, prompting further investigation into the elevated CK levels.

Findings:

• Plasma CK electrophoresis revealed the presence of CK-MM and a significant band of CK-BB (53% of total CK activity), with no detectable CK-MB.
• The patient was subsequently diagnosed with myelodysplasia, a premalignant hematologic condition.

Implications:

• Unexplained elevations in plasma CK-BB activity, especially in the absence of cardiac abnormalities, warrant consideration of underlying myelodysplastic syndromes or other hematologic malignancies.
• This case highlights the importance of CK isoenzyme electrophoresis in resolving discrepancies in CK activity assays and identifying non-cardiac causes of elevated CK levels.