[Interferences by a monoclonal IgM in biochemical analyses: detection and recommendations]

Area of Science:

• Clinical Chemistry
• Hematology
• Immunology

Background:

• Waldenström disease is a rare lymphoproliferative disorder characterized by monoclonal immunoglobulin M (IgM) production.
• Analytical interference in laboratory testing can lead to misdiagnosis and inappropriate treatment.
• Monoclonal proteins are known to cause various types of interference in clinical chemistry assays.

Observation:

• A patient with Waldenström disease exhibited analytical interference affecting lactate dehydrogenase (LDH), uric acid, and alkaline phosphatase (ALP) measurements.
• The interference was attributed to the presence of a monoclonal IgM paraprotein.
• Microscopic examination revealed potential precipitation in samples.

Findings:

• The interference mechanism is hypothesized to involve the formation of complexes between the monoclonal IgM and lithium heparin, a common anticoagulant.
• These complexes likely precipitate during automated clinical chemistry assays, causing falsely elevated or depressed results.
• The degree of interference correlated with the concentration of the monoclonal protein.

Implications:

• Clinicians must be aware of potential paraprotein-induced interference in Waldenström disease patients.
• Laboratory protocols should include methods for detecting and managing analytical interference caused by monoclonal proteins.
• Accurate interpretation of clinical chemistry results in affected patients requires consideration of the underlying hematological condition and potential interference.