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Vitamin K deficiency results from extremely inadequate intake, fat malabsorption, or use of some forms of anticoagulants.
Deficiency is particularly common among breastfed infants. It impairs clotting. Diagnosis is suspected based on routine coagulation study findings and confirmed by response to vitamin K. Treatment consists of vitamin K given orally or, when fat malabsorption is the cause or risk of bleeding is high, parenterally.
BleedingVitamin K deficiency results in defective coagulation and, potentially, bleeding.
Worldwide, vitamin K deficiency can cause infant morbidity and mortality. Vitamin K deficiency causes hemorrhagic disease of the newborn, which usually occurs 1 to 7 days postpartum. In affected newborns, birth trauma can cause intracranial hemorrhage. Newborns are prone to vitamin K deficiency because
(1) the placenta transmits lipids and vitamin K relatively poorly;
(2) the neonatal liver is immature
(3) breast milk is low in vitamin K,
(4) the neonatal gut is sterile during the first few days of life.
Late hemorrhagic disease (occurring 3 to 8 wk postpartum) is usually associated with breastfeeding, malabsorption, or a liver disorder. If the mother has ingested phenytoin
In healthy adults, dietary vitamin K deficiency is uncommon because vitamin K is widely distributed in green vegetables and the bacteria of the normal gut synthesize menaquinones. Biliary obstruction, malabsorption, cystic fibrosis, and resection of the small intestine can contribute to vitamin K deficiency.
Coumarin anticoagulants interfere with the synthesis of vitamin–K dependent coagulation proteins (factors II, VII, IX, and X) in the liver. Certain antibiotics (particularly some cephalosporins and other broad-spectrum antibiotics), salicylates, megadoses of vitamin E, and hepatic insufficiency increase risk of bleeding in patients with vitamin K deficiency.
Symptoms of Vitamin K deficiency
Bleeding is the usual manifestation. Easy bruisability and mucosal bleeding can occur. Oozing of blood from puncture sites or incisions may happen.
In infants, hemorrhagic disease of the newborn and late hemorrhagic disease may cause cutaneous, GI, intrathoracic, or, in the worst cases, intracranial bleeding. If obstructive jaundice develops, bleeding—if it occurs—usually begins after the 4th or 5th day. It may begin as a slow ooze from a surgical wound, the gums, the nose, or GI mucosa, or it may begin as massive bleeding into the GI tract.
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