Caution with interpreting laboratory results after lipid rescue therapy

Area of Science:

• Clinical Toxicology
• Clinical Chemistry

Background:

• Intravenous lipid rescue therapy (LRT) is used to manage drug toxicity.
• The impact of LRT on laboratory test results in overdose scenarios is not well-established.

Observation:

• A patient presenting with an overdose of diphenhydramine, amitriptyline, and acetaminophen (APAP) received LRT.
• Initial laboratory results showed elevated aspartate aminotransferase (AST) and APAP levels.
• Post-LRT, AST levels became undetectable, despite a rising clinical course.

Findings:

• Falsely low AST levels were observed after LRT administration, likely due to extreme lipemia.
• Lipid concentrations exceeding 400 mg/dL are known to interfere with AST measurements on the Siemens Vista 1500 analyzer.
• The undetectable AST result was deemed erroneous given the patient's clinical presentation.

Implications:

• LRT can induce significant lipemia, potentially interfering with liver enzyme assays.
• Abnormal laboratory values in patients receiving LRT should be repeated or analyzed using methods to mitigate lipemic interference.
• Careful interpretation of laboratory results is crucial when LRT is administered in overdose management.