Thrombin Time and Protamine Thrombin

Coagulation

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Description

The Thrombin time assesses the functionality of the fibrinogen to fibrin conversion step in the common pathway of coagulation. In the test Thrombin is added to patient plasma and cleaves first fibrinopeptide A, followed by fibrinopeptide B. This leads to conversion of fibrinogen to fibrin monomers and later polymers. The time taken to clot formation is influenced by the concentration and structure of the fibrinogen molecule and the action of any inhibitors present.

A prolonged thrombin can be caused by one or more of the following: -

-           Reduced fibrinogen concentration (particularly < 1.0 g/l)

-           Congenital or acquired dysfibrinogenaemia

-           Presence of Heparin, Hirudin, Lepirudin, DOAC’s

-           Presence of high concentrations of D-dimers (FDPs)

A Thrombin time with protamine sulphate is used to confirm the presence of Heparin as a cause of a prolonged thrombin time (TT). Protamine sulphate corrects the effect of heparin depending on concentration used.

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Sample Type

Plasma (Citrate 2.7ml Blue) x 1

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Reference Range

Current reference range is indicated on the report.

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Turnaround Time

Within 1 hour

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Testing Frequency

Daily/continuous processing 24hrs

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External Notes

The accuracy of all coagulation tests is greatly influenced by pre analytical variables. It is essential that sample quality is given the highest of priorities. Samples which fail to meet quality criteria including age of sample, specimen fill ( >90% ), haemolysed, clotted or activated samples will be rejected and a repeat sample requested.

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Patient Preparation

No special requirements.

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References

Guidelines on the Laboratory aspects of assays used in haemostasis and thrombosis. Mackie I, Cooper P, Lawrie A, Kitchen S, Gray E, Laffan M.

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Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.