Which of the following is caused by vitamin K deficiency?

December 6, 2025 •

3 min read

According to the National Institutes of Health, vitamin K deficiency is rare in healthy adults but is a significant concern for newborns, who are routinely given an injection at birth. In both cases, a primary condition caused by vitamin K deficiency is impaired blood clotting, which can lead to excessive bleeding.

Quick Summary

Vitamin K deficiency causes hemorrhagic issues due to impaired blood clotting, impacting both adults and newborns. Symptoms include easy bruising, excessive bleeding, and internal hemorrhages. Left untreated, it can lead to serious complications and even death in severe cases.

Key Points

Blood Clotting Failure: The primary effect of vitamin K deficiency is impaired blood coagulation, leading to excessive bleeding and easy bruising.
Newborn Risk: Infants are at high risk for Vitamin K Deficiency Bleeding (VKDB) because of low placental transfer and insufficient stores at birth, making a preventative injection crucial.
Gastrointestinal Bleeding: A severe deficiency can cause internal bleeding in the stomach or intestines, resulting in bloody or dark, tarry stools.
Weakened Bones: Long-term deficiency is linked to decreased bone mineralization, which may increase the risk of osteoporosis and fractures.
Vulnerable Populations: Adults with fat malabsorption disorders, those on long-term antibiotics or blood thinners, and newborns are the most at risk for vitamin K deficiency.
Cardiovascular Health: Some research suggests a potential link between low vitamin K and an increased risk of cardiovascular issues.

What is Vitamin K and Why is it Essential?

Vitamin K is a fat-soluble vitamin crucial for the body's normal functioning. Its primary role involves synthesizing proteins necessary for blood coagulation, also known as blood clotting. A deficiency in this vital nutrient can lead to a range of health issues, with the most immediate and dangerous consequence being defective blood clotting, which can result in excessive and uncontrolled bleeding or hemorrhaging. Beyond its role in coagulation, vitamin K also plays a part in maintaining strong bones and potentially protecting against cardiovascular disease.

The Direct Result: Bleeding and Hemorrhage

The most well-known symptom of vitamin K deficiency is defective blood clotting, which can lead to excessive bleeding. This is because without sufficient vitamin K, the liver cannot produce the necessary coagulation factors, such as prothrombin. This can manifest in several ways, from minor issues to life-threatening complications. In adults, this can cause easy bruising, nosebleeds, bleeding from the gums, and excessively heavy menstrual bleeding. In severe cases, internal bleeding in the stomach or gastrointestinal tract may occur, resulting in tarry, dark stools.

The Special Case of Newborns: Vitamin K Deficiency Bleeding (VKDB)

Newborn infants are particularly vulnerable to vitamin K deficiency, a condition known as Vitamin K Deficiency Bleeding (VKDB). They are at risk because only small amounts of vitamin K are transferred across the placenta, and breast milk contains very low levels of the vitamin. A newborn's intestines also do not yet have the bacteria needed to produce their own vitamin K. To prevent VKDB, which can cause life-threatening intracranial hemorrhages, a vitamin K injection is routinely administered to infants shortly after birth.

Other Health Impacts of Vitamin K Deficiency

While bleeding is the most immediate and severe symptom, research also suggests that a chronic vitamin K deficiency can affect bone health and increase cardiovascular risks.

Poor Bone Health: Vitamin K is involved in the carboxylation of osteocalcin, a protein that helps mineralize bones. A long-term deficiency can lead to decreased bone mineralization, potentially contributing to osteoporosis and a higher risk of fractures.
Increased Cardiovascular Risk: Some evidence indicates that inadequate vitamin K levels might heighten the risk of cardiovascular diseases by promoting arterial calcification, which reduces arterial elasticity.

Causes of Vitamin K Deficiency

Though uncommon in healthy adults with a balanced diet, several factors can lead to vitamin K deficiency:

Fat Malabsorption Disorders: Since vitamin K is fat-soluble, conditions that impair fat absorption can significantly reduce its uptake. These include cystic fibrosis, celiac disease, ulcerative colitis, and chronic liver or biliary diseases.
Medications: Certain drugs can interfere with vitamin K metabolism or production. Long-term antibiotic use can kill off gut bacteria that produce menaquinone (Vitamin K2), while blood-thinning medications like warfarin intentionally block the function of vitamin K.
Nutritional Factors: A severely deficient diet lacking in vitamin K-rich foods or a diet extremely low in fat can both be contributing factors.
Newborn Vulnerability: As mentioned, infants are born with low stores and are reliant on supplements or formula for adequate intake.

Comparison of Vitamin K Deficiency Symptoms


Symptom	Adults	Newborns
Bleeding	Easy bruising, nosebleeds, gum bleeding, gastrointestinal bleeding, heavy menstrual periods.	Bleeding from the umbilical cord site, injection sites, nose, gums, or circumcision site.
Internal Hemorrhage	Can occur in the gastrointestinal tract, causing dark, tarry stools or bloody urine.	Potentially severe and life-threatening intracranial hemorrhage (bleeding in the brain).
Skin	Easy bruising, tiny blood clots under fingernails, red spots (petechiae).	Bruising on the head or face, pale skin.
Gastrointestinal	Dark, tarry stools; bloody urine.	Vomiting blood, dark and sticky stools.
Other Signs	Can contribute to poor bone mineralization over the long term.	Irritability, seizures, or excessive sleepiness in the case of a brain bleed.

Conclusion

In summary, the most serious condition caused by vitamin K deficiency is defective blood clotting, leading to excessive and uncontrolled bleeding. While rare in healthy adults, certain medical conditions and medications can increase the risk. For newborns, a vitamin K injection at birth is a critical preventive measure to avoid life-threatening hemorrhagic disease. Chronic deficiency can also negatively impact long-term bone health and cardiovascular function. Anyone with unexplained bruising or bleeding should seek medical attention, as it may be a sign of this deficiency. Prevention in adults is typically achieved through a balanced diet rich in leafy greens and a regular medical review if taking interfering medications. For more detailed information on preventing vitamin K deficiency in newborns, consult the Centers for Disease Control and Prevention guidelines.

Frequently Asked Questions

The main symptom of vitamin K deficiency is defective blood clotting, which can lead to excessive bleeding and easy bruising.

Newborns are susceptible because vitamin K does not transfer efficiently through the placenta, and breast milk is low in the vitamin. Their gut bacteria, which help produce vitamin K, are also not yet fully developed.

Yes, a severe vitamin K deficiency can cause internal hemorrhage, particularly in the gastrointestinal tract, which can be indicated by bloody or tarry stools.

Conditions that impair fat absorption, such as cystic fibrosis, celiac disease, and certain liver diseases, increase the risk of vitamin K deficiency.

Treatment for vitamin K deficiency typically involves administering a vitamin K supplement, often phytonadione, either orally, subcutaneously, or intravenously depending on the severity.

Yes, certain blood-thinning medications like warfarin work by blocking the action of vitamin K. Patients on these drugs must maintain a consistent vitamin K intake.

Good sources of vitamin K include green leafy vegetables like spinach, kale, and broccoli, as well as some vegetable oils and fermented foods.