Which vitamin deficiency can lead to an increase in prothrombin time?

A deficiency in vitamin K can lead to an increase in prothrombin time due to vitamin K's critical role in the synthesis of several key proteins involved in blood coagulation, including prothrombin itself. Prothrombin is a clotting factor that is essential for the proper formation of blood clots.

When the body lacks sufficient vitamin K, the production of prothrombin and other vitamin K-dependent clotting factors, such as factor VII, IX, and X, is impaired. This impairment can result in a longer time for blood to clot, which is reflected in an increased prothrombin time when tested.

Vitamin K is primarily obtained through dietary sources such as leafy green vegetables, and its deficiency can occur in cases of malabsorption, certain medical conditions, or insufficient dietary intake. This biochemical understanding highlights why vitamin K is specifically important for maintaining proper coagulation and why its deficiency is associated with increased prothrombin time.

In contrast, deficiencies in vitamins C, A, and D do not directly affect prothrombin time in the same manner, as they are not involved in the synthesis of coagulation factors.