Tests
A two-staged test with purified coagulation factors in the first stage, and a FXa-specific chromogenic substrate in the second stage. In the first stage, diluted sample plasma, which has been treated with Al(OH)3 to remove prothrombin, is mixed with a combined reagent (human serum, factor V, phospholipids and calcium). In the second stage, a subsample from the first stage is mixed with normal plasma, providing prothrombin and fibrinogen, and the clotting time is measured to deduce the amount of FVIII present.
For professionals
Indicators
A nitrogenous compound containing a carbonyl group attached to two amine groups with osmotic diuretic activity. In vivo, urea is formed in the liver via the urea cycle from ammonia and is the final end product of protein metabolism. Administration of urea elevates blood plasma osmolality, resulting in enhanced flow of water from tissues, including the brain, cerebrospinal fluid and eye, into interstitial fluid and plasma, thereby decreasing pressure in those tissues and increasing urine outflow.