All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
Causes of increased and decreased clotting time
Medical expert of the article
Last reviewed: 06.07.2025
The onset of blood clotting in a healthy person is from 30 seconds to 2 minutes, the end is from 3 to 5 minutes. Blood is taken from the finger into a clean and dry capillary from the Panchenkov apparatus. The first drop of blood is removed with a swab, then a column of blood 25-30 mm high is collected in the capillary and transferred to the middle of the capillary tube. The stopwatch is turned on and every 30 seconds the capillary is tilted at an angle of 30-45°. The blood moves freely inside the capillary. With the onset of clotting, its movement slows down. At the moment of complete clotting, the blood stops moving.
Blood clotting time is an approximate indicator of a multi-stage enzymatic process, as a result of which soluble fibrinogen is converted into insoluble fibrin. This indicator characterizes the clotting process as a whole and does not allow identifying the mechanisms leading to its disruption.
Blood clotting time can be shortened only as a result of accelerated formation of blood prothrombinase (Phase I of clotting - increased contact activation, decreased level of anticoagulants). Therefore, shortening of blood clotting time always indicates increased formation of prothrombinase in the patient's body. Due to the fact that blood prothrombinase is easily replaced by tissue prothrombinase to enhance clotting processes, the formation of which is completed 2-4 times faster (in 1-2 minutes), shortening of blood clotting time is often due to the appearance of tissue thromboplastin in the bloodstream due to mechanical tissue damage, burns, extensive surgeries, transfusion of incompatible blood, sepsis, vasculitis, etc. Shortening of clotting time indicates the need to prevent hypercoagulation, which often threatens thrombosis and thromboembolism.
Blood clotting slows down significantly due to congenital or acquired deficiency of prothrombin-forming factors (primarily VIII, IX and XI), with an increase in the concentration of anticoagulants in the blood, as well as fibrinogen and fibrin degradation products (FDP).
Diseases and conditions associated with changes in blood clotting time
| Increased clotting time | Decrease in clotting time |
Significant deficiency of plasma factors (IX, VIII, XII, I, factors included in the prothrombin complex) Hereditary coagulopathies Disorders of fibrinogen formation Liver diseases Heparin treatment Circulating anticoagulants |
Hypercoagulation after massive bleeding, in the postoperative and postpartum periods Stage I (hypercoagulable) DIC syndrome Side effects of oral contraceptives |
[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ], [ 7 ], [ 8 ], [ 9 ], [ 10 ], [ 11 ]