Question

a 71 - year - old female patient tells you she has been feeling really tired for a few days. her blood chemistry reveals elevated ldh and cpk. you call the lab and ask them to run cpk isoenzymes on her specimen. they later report to you that the cpk elevation is primarily due to an increase in cpk - mb. you re - test daily over the next three days and find that the level is returning to normal. the most likely diagnosis for this patient is __________. a) chronic pulmonary dysfunction b) chronic hepatitis c) rhabdomyolysis d) acute pancreatitis e) acute myocardial infarction

Explanation:

• Chronic pulmonary dysfunction: Usually associated with respiratory symptoms like shortness of breath, cough, and abnormal lung function tests. There is no indication of respiratory - related issues in the patient's description.
• Chronic hepatitis: Characterized by liver - related symptoms such as jaundice (yellowing of the skin and eyes), abdominal pain in the right upper quadrant, and abnormal liver function tests (e.g., elevated alanine aminotransferase (ALT), aspartate aminotransferase (AST)). The patient's symptoms and lab findings (elevated LDH, CPK, and CPK - MB) are not typical for chronic hepatitis.
• Rhabdomyolysis: Leads to elevated CPK, but the isoenzyme is usually CPK - BB (brain type) or CPK - MM (muscle type) in non - cardiac muscle breakdown. CPK - MB is mainly associated with cardiac muscle.
• Acute pancreatitis: Typically presents with severe abdominal pain (often in the epigastric region radiating to the back), and abnormal pancreatic enzymes like amylase and lipase. The patient's main symptoms (fatigue) and lab findings (elevated LDH, CPK, and CPK - MB) do not strongly suggest acute pancreatitis.
• Acute myocardial infarction (AMI):
• CPK - MB is an isoenzyme of creatine phosphokinase that is predominantly found in cardiac muscle. Elevated CPK - MB (especially when it is the main contributor to the CPK elevation) is a key marker for AMI.
• LDH (lactate dehydrogenase) is also elevated in AMI.
• The time course of CPK - MB returning to normal over a few days (as in this case) is consistent with the natural history of AMI (CPK - MB peaks 12 - 24 hours after the infarction and returns to normal within 2 - 3 days).

Answer:

E. Acute myocardial infarction