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Interference of M-protein on prothrombin time test - case report

Sandra Margetić1, Ivana Ćelap1, Lora Dukić1

  • 1Clinical Institute of Chemistry, Medical School University Hospital Sestre milosrdnice, Zagreb, Croatia.

Biochemia Medica
|June 28, 2016
PubMed

Insights

Monoclonal gammopathy can interfere with laboratory coagulation tests, specifically prothrombin time (PT) and thrombin time (TT). This case highlights how abnormal PT results led to the diagnosis of monoclonal gammopathy in an elderly patient.

Area of Science:

  • Clinical Chemistry
  • Hematology
  • Immunology

Background:

  • Routine coagulation testing is crucial for assessing hemostasis and diagnosing bleeding disorders.
  • Monoclonal gammopathy, characterized by the overproduction of a single type of immunoglobulin, can manifest with various clinical complications.

Observation:

  • An 88-year-old male presented with unmeasurable prothrombin time (PT) and normal activated partial thromboplastin time (aPTT) during routine testing.
  • Subsequent tests revealed persistently unmeasurable PT, prolonged thrombin time (TT), and a visible gelatinous precipitate in refrigerated plasma samples.
  • Laboratory findings indicated the presence of monoclonal protein (M-protein), specifically IgG lambda, suggesting monoclonal gammopathy.

Findings:

  • The patient's unmeasurable PT results were corrected to 67% activity in a mixing test with normal plasma, indicating in vitro interference.
  • Prolonged TT results suggested that the M-protein impacted fibrin polymerization, affecting this global coagulation assay.
  • Coagulation factor activities (II, V, VII, X) were within normal or elevated ranges, ruling out factor deficiencies as the cause of PT abnormalities.

Implications:

  • This case underscores the importance of recognizing M-protein interference in coagulation assays, particularly PT and TT.
  • Abnormal coagulation test results in the presence of M-protein warrant further investigation to differentiate between in vitro interference and true hemostatic abnormalities.
  • Accurate diagnosis of monoclonal gammopathy is essential for appropriate patient management and monitoring.
Keywords:
M-proteininterferencemonoclonal gammopathyprothrombin timethrombin time

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