Vitamin K deficiency is most common in infants, especially those who are breastfed. The deficiency can cause bleeding; therefore, all newborns should be given a vitamin K injection.
Bleeding, the main symptom, can be life threatening in newborns.
Blood tests to check how quickly blood clots can confirm the diagnosis.
All newborns should be given a vitamin K injection.
Vitamin K supplements taken by mouth or injected under the skin can correct the deficiency.
(See also Overview of Vitamins.)
Vitamin K has two forms:
Phylloquinone: This form occurs in plants and is consumed in the diet. It is absorbed better when it is consumed with fat. Phylloquinone is not toxic.
Menaquinone: This form is produced by bacteria in the intestine, but only small amounts of it are produced. In some countries, this form is used for supplementation.
Vitamin K, like vitamins A, D, and E, is a fat-soluble vitamin, which dissolves in fat and is best absorbed when eaten with some fat. Good sources of vitamin K include green leafy vegetables (such as collards, spinach, and kale) and soybean and canola oils.
Vitamin K is necessary for the synthesis of the proteins that help control bleeding (clotting factors) and thus for the normal clotting of blood. It is also needed for healthy bones and other tissues.
In healthy adults, vitamin K deficiency is uncommon because many green vegetables contain vitamin K and bacteria in the intestine produce vitamin K.
Anticoagulants are given to people with conditions that increase the risk of blood clots. These conditions include having to stay in bed (for example, because of an injury or illness), recovering from surgery, and having atrial fibrillation
Causes of Vitamin K Deficiency
Vitamin K deficiency can result from the following:
Lack of vitamin K in the diet
A very low fat diet because vitamin K is best absorbed when eaten with some fat
Disorders that impair fat absorption and that thus reduce the absorption of vitamin K (such as blockage of the bile ducts or cystic fibrosis)
Certain medications, including antiseizure medications, and some antibiotics
Newborns are prone to vitamin K deficiency because of the following:
Only small amounts of vitamin K pass from the mother to the fetus during pregnancy.
During the first few days after birth, the newborn's intestine has not yet acquired bacteria to produce vitamin K.
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Symptoms of Vitamin K Deficiency
The main symptom of vitamin K deficiency is bleeding (hemorrhage)—into the skin (causing bruises), from the nose, from a wound, in the stomach, or in the intestine. Sometimes bleeding in the stomach causes vomiting with blood. Blood may be seen in the urine or stool, or stools may be tarry black.
In newborns, life-threatening bleeding within or around the brain may occur.
Having a liver disorder increases the risk of bleeding, because clotting factors are made in the liver.
Vitamin K deficiency may also weaken bones.
Diagnosis of Vitamin K Deficiency
Blood tests
Doctors suspect vitamin K deficiency when abnormal bleeding occurs in people with conditions that put them at risk.
Blood tests to measure how quickly blood clots are done to help confirm the diagnosis. Knowing how much vitamin K people consume helps doctors interpret results of these blood tests. Sometimes the vitamin K level in the blood is measured.
Treatment of Vitamin K Deficiency
For all newborns, a vitamin K injection
For the deficiency, vitamin K by mouth or by injection
A vitamin K injection in the muscle is recommended for all newborns to reduce the risk of bleeding within the brain after delivery.
If vitamin K deficiency is diagnosed, vitamin K is usually taken by mouth or given by injection under the skin. If a medication is the cause, the dose of the medication is adjusted or extra vitamin K is given.
