ID 10. Beginning of clotting (method of Lee-White) (min)

ID 11. End of clotting (method of Lee-White) (min)

In the body, when an injury and/or bleeding occurs, the clotting process called hemostasis begins. This process involves in part a series of sequential chemical reactions called the coagulation cascade, in which coagulation or "clotting" factors are activated one after another and result in the formation of a clot. There must be a sufficient quantity of each coagulation factor, and each must function properly, in order for normal clotting to occur. Too little can lead to excessive bleeding; too much may lead to excessive clotting.

Lee-White clotting time (LWCT) is considered normal when sample clotted in up to 9 minutes. Besides, the interval between the beginning and the end of clotting is important, and it should exceed 30 seconds.

The interaction between plasma kallikreins and tissue kallikreins (of the pancreas, salivary glands, kidneys and intestinal wall) determines the time of beginning and end of blood coagulation. An equally important role in the formation of this time interval belongs to platelets and haematocrit.

The plasma kinin system also called the kinin–kallikrein system, consists of blood proteins that play an important role in inflammation, blood pressure control, coagulation and pain. Kinins are polypeptides derived from naturally occurring plasma protein substrates (kininogen). It is known that kinins are inflammatory mediators that cause dilation of blood vessels and increased vascular permeability. Five principal pharmacological actions have been attributed to plasma kinins: stimulation of some smooth muscle, increase in vascular permeability, vasodilation, leucotaxis and induction of pain.

The current model of coagulation in vivo emphasizes tissue factor as an initiator of coagulation activation, underlines the main role of thrombin in amplification of coagulation, and the interaction of coagulation factors with blood cells and endothelial cells (Hoffman & Monroe, 2007).

Abnormalities. Disorders or diseases caused or related.

The reasons for abnormal results include hemophilia, liver disease, vitamin K deficiency, or a coagulation factor deficiency (e.g., factor VII deficiency). It’s also useful in monitoring those who take medications that affect clotting, such as warfarin (Coumadin).

In people with abnormalities of coagulation time, the test for prothrombin time (PT) and a partial thromboplastin time (PTT) is recommended for differentiation.

Interpretation of PT and PTT in Patients with a Bleeding or Clotting Syndrome

Some antibiotics can increase the time of coagulation. Barbiturates, oral contraceptives and hormone-replacement therapy (HRT), and vitamin K (either in a multivitamin or liquid nutrition supplement) may decrease clotting time.

Drinking alcohol can also affect the results. Certain foods, such as beef and pork liver, green tea, broccoli, chickpeas, kale, turnip greens, and soybean products, contain large amounts of vitamin K and can alter the results. It is important that a healthcare provider knows about all of the drugs, supplements, and foods that you have consumed recently so that the results are interpreted and used correctly.

1.        Jose Diego de Brito Sousa et al. Accuracy of the Lee–White Clotting Time Performed in the Hospital Routine to Detect Coagulopathy in Bothrops atrox Envenomation. Am J Trop Med Hyg. 2018 May; 98(5): 1547–1551, doi: 10.4269/ajtmh.17-0992

2.        Duchene (2011). "Kallikrein-kinin kystem in inflammatory diseases". Kinins. De Gruyter. pp. 261–272. ISBN 978-3-11-025235-4.

3.        MELMON, K., CLINE, M. Interaction of Plasma Kinins and Granulocytes. Nature 213, 90–92 (1967). https://doi.org/10.1038/213090a0