Vitamin K Deficiency: The Disease and Its Effects

According to the Centers for Disease Control and Prevention (CDC), all newborns are at risk for Vitamin K Deficiency Bleeding (VKDB), a serious condition, which is why a vitamin K shot is recommended at birth to prevent potentially life-threatening hemorrhage. In adults, while rare, vitamin K deficiency can also cause significant health issues related to blood clotting and bone metabolism.

Quick Summary

Severe vitamin K deficiency results in a disease characterized by uncontrolled bleeding and impaired blood clotting, known as Vitamin K Deficiency Bleeding (VKDB) in infants. This condition occurs due to inadequate production of essential clotting factors, leading to hemorrhage, easy bruising, and potential complications involving bone and cardiovascular health.

Key Points

• Bleeding Disorders (VKDB): A deficiency in vitamin K primarily causes bleeding disorders due to the impaired synthesis of crucial blood-clotting factors, leading to hemorrhage.

• Infants at High Risk: Newborns are particularly susceptible to Vitamin K Deficiency Bleeding (VKDB) because of poor placental transfer, a sterile gut, and low levels in breast milk.

• Underlying Causes in Adults: In adults, deficiency is most often linked to fat malabsorption disorders, liver disease, or certain medications like anticoagulants and long-term antibiotics.

• Symptoms Include Excessive Bleeding: Signs of deficiency range from easy bruising and nosebleeds to more severe internal bleeding, including gastrointestinal and intracranial hemorrhage.

• Impacts Bone Health: Beyond bleeding, vitamin K deficiency can also contribute to poor bone development, leading to conditions like osteoporosis over time.

• Preventable and Treatable: VKDB in newborns is preventable with a standard vitamin K injection at birth. In both infants and adults, treatment involves vitamin K supplementation.

• Rich Dietary Sources: Excellent food sources of vitamin K include green leafy vegetables like kale and spinach, as well as certain oils, fermented foods, and eggs.

Understanding Vitamin K and Its Crucial Role

Vitamin K is a fat-soluble vitamin essential for numerous bodily functions. Its primary role is to serve as a cofactor for the enzyme gamma-glutamyl carboxylase, which is necessary for the production of several key proteins involved in the body's natural coagulation, or blood clotting, process. Specifically, these include clotting factors II (prothrombin), VII, IX, and X, which are produced in the liver. Without sufficient vitamin K, these proteins are not activated, compromising the blood's ability to clot properly and leading to a significant bleeding risk. In addition to its role in blood clotting, vitamin K is also vital for healthy bone metabolism and cardiovascular function, as it helps regulate proteins that guide calcium utilization.

The Disease: Vitamin K Deficiency Bleeding (VKDB)

While vitamin K deficiency is uncommon in healthy adults, it presents a critical concern in newborns, a condition specifically named Vitamin K Deficiency Bleeding (VKDB). This is due to several factors unique to infancy: poor placental transfer of vitamin K from mother to fetus, a sterile newborn gut lacking the bacteria that produce vitamin K, and the low vitamin K content of breast milk. This condition can manifest in different forms:

• Early VKDB: Occurs within the first 24 hours of birth, often severe and linked to maternal medication use during pregnancy that interferes with vitamin K.
• Classical VKDB: Presents between days 2 and 7, and is characterized by bleeding from the umbilical cord, circumcision site, or nose.
• Late VKDB: Occurs from 1 week up to 6 months of age, most commonly in exclusively breastfed infants who did not receive the preventive vitamin K shot at birth. This form can result in life-threatening intracranial hemorrhage.

Causes of Vitamin K Deficiency in Adults

Though rare, vitamin K deficiency in adults is typically associated with underlying health issues rather than dietary intake alone. These include:

• Malabsorption disorders: Conditions like celiac disease, Crohn's disease, or cystic fibrosis impair fat absorption, which is necessary for absorbing fat-soluble vitamins like vitamin K.
• Liver disease: The liver is responsible for producing the vitamin K-dependent clotting factors. Severe liver damage can impede this process.
• Medications: Certain drugs, including long-term antibiotic use that disrupts gut bacteria and anticoagulants like warfarin, can interfere with vitamin K metabolism.
• Dietary issues: Though less common, a very low-fat diet or poor nutrition over an extended period can lead to deficiency.

Symptoms and Complications of Vitamin K Deficiency

The most prominent sign of vitamin K deficiency is abnormal bleeding, which can occur both externally and internally. The severity of symptoms depends on the degree of the deficiency.

Common Symptoms:

• Easy and excessive bruising
• Bleeding from the nose or gums
• Excessive bleeding from small cuts, injections, or surgical wounds
• Blood in the urine or stool, which may appear dark and tarry
• Heavy menstrual bleeding
• Small red spots under the skin caused by bleeding from tiny capillaries (petechiae)

Serious Complications:

• Hemorrhage: This is the uncontrolled bleeding that is the most life-threatening complication, particularly intracranial hemorrhage in infants.
• Weakened bones: Inadequate vitamin K is linked to poor bone mineralization, increasing the risk of osteopenia or osteoporosis over time.
• Cardiovascular disease: Emerging evidence suggests a link between vitamin K deficiency and cardiovascular risks, possibly due to effects on arterial calcification.

Diagnosis and Treatment of Vitamin K Deficiency

Diagnosis involves a physical examination and reviewing medical history, especially for infants or adults with risk factors. Blood tests are crucial for confirmation.

The primary blood test is the prothrombin time (PT) or international normalized ratio (INR), which measures how long it takes for a blood sample to clot. An abnormally prolonged clotting time can indicate vitamin K deficiency.

Treatment depends on the age and severity of the deficiency:

• Newborns: Standard practice is a prophylactic vitamin K injection at birth to prevent VKDB.
• Adults: Treatment involves vitamin K supplementation, given orally or via injection depending on the cause and severity. For cases caused by malabsorption, a parenteral (non-oral) route may be necessary. A doctor may also adjust medications or manage the underlying condition causing the deficiency.

Comparison of Vitamin K Deficiency in Infants vs. Adults

Feature	Infants (Newborns)	Adults
Primary Cause	Low placental transfer, low breast milk content, sterile gut flora.	Underlying malabsorption disorders, liver disease, or medication use.
Disease Name	Vitamin K Deficiency Bleeding (VKDB).	Hypoprothrombinemia or vitamin K deficiency bleeding.
Bleeding Risks	Life-threatening intracranial hemorrhage is a major concern, particularly in late VKDB.	Excessive bruising, nosebleeds, internal bleeding (e.g., gastrointestinal hemorrhage).
Bone Impact	Poor bone development is a potential chronic issue if deficiency is not addressed early.	Increased risk of osteoporosis and fractures due to disrupted bone mineralization.
Prevention	Standard prophylactic intramuscular injection at birth.	Consuming a balanced diet rich in leafy greens and managing any underlying health conditions.
Treatment	Vitamin K injection (if prophylaxis not administered) or supplements.	Oral or parenteral vitamin K supplements, addressing the root cause.

Prevention and Dietary Sources

For adults, prevention of vitamin K deficiency primarily involves consuming a balanced diet rich in vitamin K and managing any medical conditions that affect its absorption. Vitamin K exists in two main forms: K1 (phylloquinone) from plants and K2 (menaquinone) from animal and fermented foods and produced by gut bacteria.

Foods Rich in Vitamin K1:

• Green leafy vegetables such as kale, spinach, and collard greens
• Broccoli
• Brussels sprouts
• Cabbage

Foods Containing Vitamin K2:

• Fermented foods like natto
• Cheeses
• Eggs
• Meat

Pairing vitamin K-rich foods with a source of dietary fat (e.g., olive oil dressing on a salad) can improve absorption, as it is a fat-soluble vitamin.

Conclusion

While clinically significant vitamin K deficiency is rare in healthy adults, the potential consequences, particularly for infants, underscore the vitamin's critical importance. The most notable disease caused by a deficiency is Vitamin K Deficiency Bleeding (VKDB), a serious and potentially fatal condition in newborns that is easily preventable with a vitamin K shot at birth. In adults, deficiency is usually the result of an underlying medical condition, like malabsorption or liver disease, and can lead to excessive bleeding and weakened bones. Fortunately, with proper diagnosis through blood tests and timely treatment involving supplementation, the deficiency can be managed effectively. Maintaining a balanced diet with ample vitamin K-rich foods is key to preventing deficiency, especially for at-risk individuals.

Visit the NIH Office of Dietary Supplements for more detailed information on Vitamin K.

Frequently Asked Questions

What is the primary function of vitamin K?

The primary function of vitamin K is to activate proteins in the liver that are essential for blood clotting (coagulation). Without sufficient vitamin K, these proteins cannot function properly, leading to a risk of excessive bleeding.

What does VKDB stand for?

VKDB stands for Vitamin K Deficiency Bleeding. It is a severe bleeding disorder that occurs in infants who do not have enough vitamin K. This is a potentially life-threatening condition that can be prevented with a vitamin K shot at birth.

How is vitamin K deficiency diagnosed in adults?

Vitamin K deficiency in adults is typically diagnosed with a blood test called a prothrombin time (PT) or international normalized ratio (INR). A prolonged clotting time indicates a deficiency in vitamin K-dependent clotting factors.

What foods are rich in vitamin K?

Foods rich in vitamin K include green leafy vegetables such as kale, spinach, and broccoli (K1). The K2 form is found in smaller amounts in some animal products, cheeses, and fermented foods like natto.

Can taking antibiotics cause vitamin K deficiency?

Yes, prolonged use of certain antibiotics can disrupt the bacteria in the gut responsible for producing vitamin K2, potentially leading to a deficiency.

What are the long-term effects of vitamin K deficiency?

The most concerning long-term effects of chronic vitamin K deficiency can include weakened bones (osteoporosis) due to impaired bone mineralization, as well as an increased risk of cardiovascular disease.

Is vitamin K deficiency common in healthy adults?

No, vitamin K deficiency is rare in healthy adults. It is primarily a concern for newborns and individuals with pre-existing health conditions that affect absorption, such as malabsorption disorders or liver disease.