Lupus Anticoagulant Blood Test

The dRVVT (Dilute Russell Viper Venom Time) normal control measures how long it takes for a standardised control plasma sample to clot using the Russell Viper Venom test. This serves as the baseline reference point against which your own blood clotting time is compared. The control essentially tells the laboratory how long normal blood should take to clot under these testing conditions. This measurement on its own doesn't provide information about your clotting function - it's used in combination with your actual dRVVT test result to calculate the dRVVT ratio.

The dRVVT ratio is calculated by dividing your dRVVT test result by the dRVVT normal control result, revealing whether lupus anticoagulant antibodies are present in your blood. While the name anticoagulant suggests these antibodies prevent clotting, they actually increase your risk of inappropriate blood clots (thrombosis). A normal ratio indicates your blood is clotting as expected, while an elevated ratio suggests the presence of lupus anticoagulant, which is associated with antiphospholipid syndrome (APS). This condition increases the risk of blood clots in veins and arteries, and is also linked to recurrent miscarriages.