ABSTRACT
Prothrombin Time and Albumin Prothrombin time (PT) and serum level of albumin are markers of liver synthetic function. Abnormalities of PT and albumin imply severe liver disease and should prompt an immediate evaluation. PT is a measure of the activity of factors II, V, VII, and X, all of which are synthesized in the liver. Because these factors are also dependent on vitamin K for synthesis, deficiencies of vitamin K also produce abnormalities of PT. Vitamin K deficiency can result from the use of antibiotics during a period of prolonged fasting, small-bowel mucosal disorders such as celiac disease, and severe cholestasis, with an inability to absorb fat-soluble vitamins. True hepatocellular dysfunction is characterized by an inability to synthesize clotting factors even when stores of vitamin K are adequate. A simple way to distinguish between vitamin K deficiency and liver dysfunction in a patient with a prolonged PT is to administer vitamin K. A 10mg dose of oral vitamin K for 3 days or 10 mg of subcutaneous vitamin K normalizes the PT within 48 hours in a vitamin K-deficient patient but has no effect on the PT in a patient with decreased liver synthetic function.
