Vitamin K and Vitamin K Deficiency Bleeding (VKDB)

Context

A study published in JAMA Pediatrics on 5 November 2026 reported a 347.1% rise in diagnosed Vitamin K Deficiency Bleeding (VKDB) rates among US infants between 2017 and 2025. During this period, newborn vitamin K injection coverage declined from 97.7% to 95.0%, raising concerns about preventable bleeding disorders.

About Vitamin K

1. Definition: Vitamin K is a fat-soluble vitamin essential for blood coagulation and bone metabolism. It occurs mainly in two forms:

1. 1. Vitamin K1 (Phylloquinone): Found primarily in green leafy vegetables, including spinach, kale and collard greens.
   2. Vitamin K2 (Menaquinones): Found in fermented foods and certain animal products; some forms are also produced by intestinal bacteria.

1. Absorption and storage: Vitamin K is absorbed with dietary fats and stored in the liver and other tissues, including bones and the brain.
2. Metabolism: It is rapidly metabolised and excreted, resulting in relatively limited body stores compared with some other fat-soluble vitamins.

Major Functions of Vitamin K

1. Blood clotting: Vitamin K enables the activation of clotting factors II, VII, IX and X, supporting normal coagulation and preventing excessive bleeding.
2. Bone metabolism: It activates osteocalcin, a protein involved in bone mineralisation, contributing to normal bone health.
3. Vascular regulation: Vitamin K activates Matrix Gla Protein (MGP), which helps inhibit abnormal calcium deposition in blood vessels; its clinical cardiovascular benefits remain uncertain.
4. Other potential roles: Researchers are investigating links with cognitive health, but evidence supporting additional clinical benefits remains inconclusive.

Vitamin K Deficiency

1. Occurrence: Clinically significant deficiency is uncommon in healthy adults because normal diets generally provide adequate vitamin K.
2. Risk factors: Fat-malabsorption disorders, certain liver diseases and medications interfering with vitamin K availability or activity can increase deficiency risks.
3. Bleeding complications: Severe deficiency impairs clotting-factor activation, potentially causing easy bruising, prolonged bleeding and serious haemorrhage.
4. Bone implications: Inadequate vitamin K may affect bone mineralisation, although evidence that supplementation prevents osteoporosis or fractures remains mixed.

What is Vitamin K Deficiency Bleeding (VKDB)?

1. Definition: VKDB, formerly called haemorrhagic disease of the newborn, is a bleeding disorder caused by insufficient vitamin K-dependent clotting activity in infants.
2. Causes in newborns: Limited placental transfer, low vitamin K content in breast milk and initially low intestinal bacterial production leave newborns vulnerable to deficiency.
3. Clinical manifestations: Bleeding may occur in the skin, gastrointestinal tract or brain; severe intracranial haemorrhage can cause permanent neurological damage or death.
4. Types of VKDB:

1. 1. Early VKDB: Occurs within 24 hours of birth, often associated with maternal medications that interfere with vitamin K metabolism.
   2. Classical VKDB: Occurs between 2 days and 1 week, commonly presenting with bruising or umbilical bleeding.
   3. Late VKDB: Occurs from approximately 1 week to 6 months, particularly among breastfed infants without adequate vitamin K prophylaxis.

Prevention of VKDB

1. Newborn prophylaxis: A single intramuscular vitamin K injection shortly after birth effectively prevents VKDB, including its potentially life-threatening late form.
2. Risk reduction: According to the CDC, infants who do not receive the injection are approximately 81 times more likely to develop late VKDB than those who receive it.
3. Public-health significance: Routine prophylaxis and parental awareness can prevent avoidable haemorrhagic complications and infant deaths.

FAQs

Q1. What type of vitamin is Vitamin K?
A fat-soluble vitamin essential for blood clotting and bone metabolism.

Q2. What are the two main forms of Vitamin K?
Phylloquinone (Vitamin K1) and menaquinones (Vitamin K2).

Q3. Which blood-clotting factors depend on Vitamin K?
Factors II, VII, IX and X.

Q4. What is Vitamin K Deficiency Bleeding (VKDB)?
A bleeding disorder in infants caused by insufficient vitamin K-dependent clotting activity.

Q5. How can VKDB be prevented?
Through a routine intramuscular vitamin K injection shortly after birth.