American Board of Surgery Qualifying Exam (ABS QE) Practice Test

What is a consequence of Vitamin K deficiency?

1. Decreased synthesis of clotting factors

2. Rickets and osteomalacia

3. Hemolytic anemia

4. Night blindness

The correct answer is: Decreased synthesis of clotting factors

Vitamin K deficiency primarily leads to decreased synthesis of clotting factors. Vitamin K is essential for the post-translational modification of several proteins required for blood coagulation, specifically factors II (prothrombin), VII, IX, and X, along with proteins C and S, which are important for regulatory functions in the clotting cascade. When vitamin K is deficient, these clotting factors cannot be effectively synthesized, resulting in impaired coagulation and an increased risk of bleeding. This could manifest as easy bruising, prolonged bleeding after cuts, or even severe hemorrhagic events in more pronounced deficiencies. Other potential consequences mentioned in the options relate to different nutrient deficiencies or conditions: rickets and osteomalacia are associated with vitamin D deficiency; hemolytic anemia can arise from various causes, including certain vitamin and mineral deficiencies, such as vitamin E; and night blindness is typically linked to vitamin A deficiency. None of these conditions directly relate to the biochemical role of vitamin K in coagulation, thereby reinforcing why decreased synthesis of clotting factors is the most accurate consequence of vitamin K deficiency.