A patient has normal creatine kinase but elevated troponin I. Which condition is most likely?

A patient has normal creatine kinase but elevated troponin I. Which condition is most likely?

• A. Acute myocardial infarction
• B. Pulmonary embolism
• C. Chronic kidney disease
• D. Liver cirrhosis

Answer: (A)

Troponin I is a cardiac-specific biomarker that rises when heart muscle is damaged. It is more sensitive and specific for myocardial injury than creatine kinase, which can come from skeletal muscle and other sources. In an acute myocardial infarction, troponin levels increase as the affected cardiomyocytes release their contents, and they can be elevated even if the total CK is normal—especially early on or in smaller infarcts where CK may not rise as clearly. So a pattern of elevated troponin I with a normal CK is most consistent with myocardial injury from an acute myocardial infarction. Pulmonary embolism can cause troponin elevation because of right-heart strain, but it’s less classic for showing this particular CK pattern. Chronic kidney disease may have chronically elevated troponin due to reduced clearance, which makes the finding less specific for an acute infarct. Liver cirrhosis doesn’t typically present with increased troponin.

Troponin I is a cardiac-specific biomarker that rises when heart muscle is damaged. It is more sensitive and specific for myocardial injury than creatine kinase, which can come from skeletal muscle and other sources. In an acute myocardial infarction, troponin levels increase as the affected cardiomyocytes release their contents, and they can be elevated even if the total CK is normal—especially early on or in smaller infarcts where CK may not rise as clearly. So a pattern of elevated troponin I with a normal CK is most consistent with myocardial injury from an acute myocardial infarction.

Pulmonary embolism can cause troponin elevation because of right-heart strain, but it’s less classic for showing this particular CK pattern. Chronic kidney disease may have chronically elevated troponin due to reduced clearance, which makes the finding less specific for an acute infarct. Liver cirrhosis doesn’t typically present with increased troponin.