Vitamin K Requirement

Vitamin K deficiency exists when chronic failure to eat sufficient amounts of vitamin K results in a tendency for spontaneous bleeding or in prolonged and excessive bleeding with trauma or injury.  Vitamin K deficiency occurs also in newborn infants, as well as in people treated with certain antibiotics.  The protein in the body most affected by vitamin K deficiency is a blood-clotting protein called prothrombin.  Aside from newborns and young infants, vitamin K deficiency is not a concern for the general population.

Vitamin K plays an important role in blood clotting.  Without the vitamin, even a small cut would cause continuous bleeding in the body, and eventually death.  Blood clotting is a process that begins automatically when any injury produces a tear in a blood vessel.  The process of blood clotting involves a collection of molecules, which circulate continuously through the bloodstream.  When an injury occurs, these molecules rapidly assemble and form the blood clot.  The clotting factors are proteins, and include proteins called Factor II, Factor VII, Factor IX, and Factor X. Factor II is also called prothrombin.  These proteins require vitamin K for their synthesis in the body.  The blood-clotting process also requires a dozen other proteins that do not need vitamin K for their synthesis.

Blood-clotting problems can also be caused by a rare genetic disease called hemophilia.  Hemophilia is not related to vitamin K deficiency.

Incidence; Causes and Development

Although vitamin K deficiency occurs in about 1% of all newborn infants, in adults it is rare.

When it occurs, it is found in people with diseases that prevent the absorption of fat.  These diseases include cystic fibrosis, celiac disease, and cholestasis.  Vitamin K deficiency can exist in adults treated with antibiotics that kill the bacteria that normally live in the digestive tract – intestinal bacteria supply part of our daily requirement of vitamin K.

Signs and Symptoms

Vitamin K deficiency can result in bleeding gums and in skin that is easily bruised.

Diagnosis and Tests

Vitamin K status is measured by the prothrombin time test.  The normal prothrombin time is about 13 seconds whereas in cases of vitamin K deficiency the prothrombin time can be several minutes.  The test involves taking a sample of blood, placing it in a machine called a FibroMeter, and measuring the time it takes for blood-clot formation.  Once vitamin K deficiency is suspected, further tests must be used to distinguish it from possible hemophilia.  Where a bleeding disorder can be corrected through vitamin K treatment, the diagnosis of vitamin K deficiency is proven to be correct.