Clinical Aspects of Vitamin K

Vitamin K has several important roles in humans, and awareness of them will enable one to prevent deficiency and avoid interactions with medications.

Deficiency of vitamin K is rare, and it tends to result from fat malabsorption problems. Since vitamin K is fat soluble, its absorption through the gastrointestinal tract has to take place in the presence of dietary fat. Patients who have malabsorption problems should take a multivitamin which includes vitamin K.

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Predisposition for vitamin K deficiency

Diseases which cause malabsorption include cystic fibrosis, Crohn disease, celiac disease, and surgical removal of part of the intestine. Gallbladder or biliary disease will present a problem because the secretion of bile enables the digestion of fat to occur. Liver disorders, malnutrition, and alcoholism may lead to vitamin K deficiency.

Patients who undergo hemodialysis may develop deficiency of vitamin K. Individuals with serious burns are also at risk. Long term antibiotic therapy of more than 10 days duration will destroy valuable intestinal bacteria that produce vitamin K, and these patients will be at risk for deficiency as well. Moreover, certain drugs to reduce the level of cholesterol in the blood may reduce the absorption of fat soluble vitamins.

Individuals with deficiency of vitamin K tend to bruise or bleed easily. Certain signs and symptoms will indicate that the patient needs vitamin K supplementation. These include excessive bleeding, frequent nosebleeds, bleeding gums, heavy menstruation, or blood in the urine or stool. However, any of those symptoms or signs may indicate other serious diseases, and a thorough medical evaluation is necessary.

Blood thinners

Of special concern is the patient who takes warfarin to thin the blood. This medication has been useful for people who have suffered blood clots in the leg or the lung, and many decades ago physicians prescribed it for individuals who had suffered a coronary thrombosis or heart attack. Despite the advantage that warfarin offers in the prevention of further blood clots, there are several precautions that the patient and physician must take.

For patients who take warfarin, hospitals and other medical centers can perform a blood test, the International Normalized Ratio (INR), to measure the time it takes for clot formation. It is essential that the patient has the test on a regular basis so the physician will know that the coagulation level of the blood is in an acceptable range. Should the blood become too thin, there is risk that these patients will bleed excessively and become severely ill.

Since the function of vitamin K is to prevent excessive bleeding, and the role of warfarin is to prevent blood clots, the patient’s dietary intake of the vitamin must be consistent. In other words, the medication may not work well if there is variation in how much vitamin K the patient takes from the diet.

The intake of alcohol may enhance warfarin’s effect, and physicians may recommend that patients who take warfarin avoid alcohol. This drug will cause the patient to bruise easily as well. Some antibiotics will lower the level of vitamin K in the blood, and they may also interact with warfarin. In any event, patients who take warfarin should inform their physician of any other medications they take. This includes vitamin supplements, herbal preparations, and over-the-counter products.

Phenytoin, an agent to treat seizures, will interfere with the body’s ability to use vitamin K.

Finally, it is important for patients who have glucose-6-phosphate dehydrogenase deficiency to know that they should never take vitamin K supplements.

References

American Cancer Society. Vitamin K.

National Institutes of Health. Warren Grant Magnuson Clinical Center. Important

Information to know when you are taking: Coumadin and vitamin K.