Definition

Vitamins are essential substances for the body and can be obtained from the food we eat or through multivitamin supplements. Generally, vitamins are stored within the body. A lack of stored vitamins leads to a condition known as vitamin deficiency. Vitamin K is one of the fat-soluble vitamins and plays a crucial role in blood clotting, bone development, and heart health.

Vitamin K exists in two forms: vitamin K1 (phylloquinone), found in plants, particularly green leafy vegetables such as spinach and kale, and vitamin K2 (menaquinone), which is naturally produced in the digestive tract and serves a similar function to K1. Vitamin K is essential for the blood clotting process, helping to stop both internal and external bleeding.

The body requires vitamin K to produce proteins necessary for blood clotting. In cases of vitamin K deficiency, the lack of these proteins disrupts the clotting process. Vitamin K deficiency is uncommon in adults, as they typically obtain sufficient K1 from their diet and K2 from internal production. Additionally, the body efficiently recycles vitamin K.

Certain conditions or medications can disrupt vitamin K metabolism, leading to deficiency. Vitamin K deficiency is more common in infants, where it is referred to as Vitamin K Deficiency Bleeding (VKDB).

Causes

While rarely found in adults, vitamin K deficiency can occur under certain circumstances, such as in individuals treated with blood thinners (anticoagulants), antibiotics that interfere with vitamin K production or absorption, insufficient dietary intake of vitamin K, or excessive intake of vitamins A or E.

Additionally, conditions that limit fat absorption (fat malabsorption), such as celiac disease, cystic fibrosis, gastrointestinal or biliary tract disorders, or having parts of the digestive tract removed (e.g., bariatric surgery), may lead to vitamin K deficiency.

In newborns, several factors contribute to vitamin K deficiency, including low vitamin K levels in breast milk, poor placental transfer of vitamin K, immature liver function, and the inability of the newborn's digestive system to produce vitamin K2 in the first few days of life.

Risk Factors

Certain medications can increase the risk of vitamin K deficiency, such as:

• Coumarin anticoagulants (e.g., warfarin), which thin the blood by disrupting the formation of proteins involved in the clotting process
• Certain antibiotics, which may reduce the body’s ability to produce or effectively use vitamin K
• Conditions leading to fat malabsorption
• Diets low in vitamin K

Symptoms

The primary symptom of vitamin K deficiency is excessive bleeding. This bleeding may occur in areas unrelated to visible wounds. Individuals may notice they bruise easily, find blood clots under the nails, bleeding in mucous membranes, or darker, tar-like bowel movements that contain blood.

Diagnosis

To diagnose vitamin K deficiency, your doctor will review your medical history to assess whether you are at risk. Typically, those at risk include individuals taking anticoagulants, antibiotics, or those with fat absorption issues.

Your doctor may also recommend a prothrombin time test (PTT) to determine if vitamin K deficiency is responsible for your symptoms. This test measures how long it takes for your blood to clot. Normally, clotting occurs within 11 to 13.5 seconds. If it takes longer, this could indicate a deficiency in vitamin K.

In newborns, doctors will look for signs of vitamin K deficiency if there is bleeding at the site where the umbilical cord was removed, on the skin, in the nose, digestive tract, or other areas, or around the genital region if the baby has been circumcised. Sudden brain bleeding, which can be life-threatening, is also a critical sign in newborns.

Management

Vitamin K deficiency is typically treated with phytonadione, a form of vitamin K1. In most cases, doctors will prescribe this as an oral medication. Alternatively, it can be administered via injection under the skin, into a vein, or into a muscle. The dose for adults generally ranges between 1 and 25 milligrams (mg).

For patients taking anticoagulants, doctors will often prescribe low doses of phytonadione, typically between 1 and 10 mg, to prevent complications that arise when anticoagulants interfere with the body's production of vitamin K.

For newborns, the American Academy of Pediatrics recommends a single injection of 0.5 to 1 mg of vitamin K1 at birth. Higher doses may be necessary if the mother is taking anticoagulants or anti-seizure medications during pregnancy.

Complications

Bleeding is the most serious complication of vitamin K deficiency and can be life-threatening, particularly in newborns. While heart-related complications are possible, further research is needed to confirm this.

Prevention

Although there is no specific daily requirement for vitamin K intake, nutritionists recommend 120 mcg per day for men and 90 mcg per day for women. Green leafy vegetables are an excellent source of vitamin K and can meet daily needs in just one serving. For newborns, a single injection of vitamin K at birth can prevent serious health issues.

Patients with fat malabsorption should consult their doctor about taking vitamin K supplements and having their levels monitored.

This advice also applies to those taking warfarin or similar anticoagulants.

When to See a Doctor?

You should contact your doctor if you experience symptoms of vitamin K deficiency. Immediate medical attention is necessary for uncontrolled bleeding. Regular check-ups are recommended to ensure adequate vitamin K levels.

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