the normal clotting time for blood is 8 to 15 minutes.
the normal clotting time for blood is 8 to 15 minutes.
what is the normal clotting time for blood?
8 to 15 minutes
clotting time









































clotting time is the time required for a sample of blood to coagulate in vitro under standard conditions.









































there are various methods for determining the clotting time, the most common being the capillary tube method. it is affected by calcium ion levels and many diseases. normal value of clotting time is 8 to 15 minutes.









































for the measurement of clotting time by test tube method, blood is placed in a glass test tube and kept at 37° c. the required time is measured for the blood to clot.
clotting time
this "in vitro" diagnostic test is based on the ability of the venom of the russell's viper to induce thrombosis. the venom contains some substances (rvv-v and rvv-x) which directly activate factor v and factor x, which turns prothrombin into thrombin in the presence of phospholipid and calcium. in the drvvt assay, low, rate-limiting concentrations of both russell's viper venom and phospholipid are used to give a standard clotting time of 23 to 27 seconds. this makes the test sensitive to the presence of lupus anticoagulants, because these antibodies interfere with the clot-promoting role of phospholipid "in vitro", and their presence results in a prolonged clotting time. a mixing study is then performed, which consists of adding an equal volume of the patient's plasma to normal plasma; in this study, one would expect the clotting time to return to the normal range if there was only a deficiency of coagulation factors alone. a prolonged clotting time of 30 seconds or greater that does not correct despite the mixing study suggests the presence of a lupus anticoagulant. an abnormal result for the initial drvvt assay should be followed by a drvvt confirmatory test. in this test, the inhibitory effect of lupus anticoagulants on phospholipids in the drvvt can be overcome by adding an excess of phospholipid to the assay. the clotting times of both the initial drvvt assay and confirmatory test are normalized and then used to determine a ratio of time without phospholipid excess to time with phospholipid excess. in general, a ratio of greater than 1.3 is considered a positive result and implies that the patient may have antiphospholipid antibodies. the drvvt test has a higher specificity than the aptt test for the detection of lupus anticoagulant, because it is not influenced by deficiencies or inhibitors of clotting factors viii, ix or xi as the venom only activates factors v and x.
dilute russell's viper venom time