American Board of Internal Medicine (ABIM) Certification Practice Exam

What is a common characteristic finding in critical illness myopathy compared to its counterpart?

1. Respiratory failure

2. High serum CK levels

3. Prolonged recovery time

4. Neurological deficits

The correct answer is: High serum CK levels

High serum creatine kinase (CK) levels are a common characteristic finding in critical illness myopathy, which is essential for distinguishing it from other conditions such as critical illness polyneuropathy. In critical illness myopathy, muscle inflammation or damage occurs, leading to elevated levels of CK in the bloodstream as muscle fibers break down. This increase in CK is significant because it indicates muscle injury, which is a hallmark of critical illness myopathy. In contrast, critical illness polyneuropathy typically does not present with elevated CK levels because it primarily affects the nerve pathways rather than causing direct muscle damage. Therefore, elevated serum CK can help clinicians identify critical illness myopathy and differentiate it from other neuromuscular disorders encountered in critically ill patients. Recognizing these elevated levels guides management strategies and can affect outcomes for affected patients.