Differential Diagnosis for Elevated Liver Enzymes

The patient presents with headache, neck pain, fevers, and a recent history of tick bite, initially treated with doxycycline. Despite a negative tick panel, the patient's liver enzymes are significantly elevated. Here's a differential diagnosis organized by category:

• Single Most Likely Diagnosis
  • Doxycycline-induced liver injury: The patient was recently started on doxycycline, and the temporal relationship between the initiation of the medication and the elevation of liver enzymes suggests a potential causative link. Doxycycline is known to cause liver injury in rare cases.
• Other Likely Diagnoses
  • Viral hepatitis: Although the tick panel was negative, other viral infections could be responsible for the liver enzyme elevation. Viral hepatitis (e.g., hepatitis A, B, or C) could present with similar symptoms and should be considered.
  • Autoimmune hepatitis: This condition can present with elevated liver enzymes and may be triggered by various factors, including medications.
• Do Not Miss Diagnoses
  • Acetaminophen toxicity: Overuse or accidental overdose of acetaminophen can lead to severe liver injury. It's crucial to inquire about the patient's use of acetaminophen or other over-the-counter medications.
  • Budd-Chiari syndrome: Although less common, this condition involves hepatic vein thrombosis and can present with acute liver injury. It's essential to consider this diagnosis due to its potential severity and need for prompt intervention.
• Rare Diagnoses
  • Wilson's disease: A genetic disorder leading to copper accumulation in the liver, which can cause liver enzyme elevation. However, it's less likely given the acute presentation and recent tick bite.
  • Alpha-1 antitrypsin deficiency: Another genetic disorder that can cause liver disease, but it's rare and typically presents in a more chronic manner.

Next Steps in Management

1. Discontinue doxycycline: Given the potential link between doxycycline and liver enzyme elevation, stopping the medication is prudent.
2. Viral hepatitis screening: Perform tests for hepatitis A, B, and C to rule out viral causes.
3. Autoimmune hepatitis workup: Consider ordering autoantibodies and immunoglobulin levels to assess for autoimmune hepatitis.
4. Acetaminophen level: Check for acetaminophen toxicity, especially if there's a suspicion of overdose.
5. Imaging studies: Consider abdominal ultrasound or CT scan to evaluate for structural liver diseases, such as Budd-Chiari syndrome.
6. Liver function tests: Continue to monitor liver enzymes and consider adding tests like prothrombin time and international normalized ratio (INR) to assess liver synthetic function.