Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1231 page)

   Use

   Detects decreased or abnormal fibrinogen.

   Detects unreported heparin use.

   Detects other thrombin inhibiting drugs, for example, hirudin, antithrombin agents such as argatroban, apixaban, and dabigatran. A new assay, the dilute thrombin time is now being offered commercially for the new antithrombin agents measurements.

   Interpretation

Causes of Increased (Prolonged) TT

   Very low fibrinogen (<80 mg/dL)

   Dysfibrinogenemia

   Interference with polymerization of fibrinogen

   Fibrin degradation products, such as DIC and pathologic or therapeutic fibrinolysis. TT is not recommended in the diagnosis of pathologic fibrinolysis or DIC because of very low specificity and low sensitivity

   High concentrations of monoclonal immunoglobulins

   Uremia

   Heparin therapy

   Limitations