Which vitamin does convert prothrombin to thrombin?

RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Applied Nutrition & Dietetics

Easy

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Explanation

Vitamin K is a fat-soluble vitamin essential for the synthesis of functional blood clotting factors in the liver.
It acts as a coenzyme for the post-translational carboxylation of precursor proteins for Factors II (prothrombin), VII, IX, and X.
This carboxylation step is mandatory for prothrombin to become functional, allowing it to bind calcium and subsequently be converted to thrombin during the coagulation cascade.
Without Vitamin K, the liver produces inactive clotting factors, leading to impaired hemostasis.

Option A: Vitamin D's primary function is regulating calcium and phosphorus homeostasis, which is critical for bone mineralization, not synthesizing clotting factors.
Option B: Vitamin A is essential for vision (as part of rhodopsin), immune function, and maintaining epithelial tissues. It is not involved in the coagulation cascade.
Option D: Vitamin B2 (Riboflavin) is a water-soluble vitamin that functions as a precursor for the coenzymes FAD and FMN, which are critical for energy metabolism and cellular respiration.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Role of vitamins in blood coagulation as background academic context rather than a clinical decision trigger.
Understanding the role of Vitamin K is critical for nurses, especially when managing patients on anticoagulant therapy like warfarin (Coumadin), which acts as a Vitamin K antagonist.
Nurses administer Vitamin K injections to all newborns prophylactically to prevent Vitamin K Deficiency Bleeding (VKDB), as infants are born with low Vitamin K stores.
Patients with liver disease or malabsorption syndromes (e.g., cystic fibrosis, Crohn's disease) are at high risk for Vitamin K deficiency and require careful monitoring for signs of bleeding.

How to Approach the Question

First, identify the key terms in the question: 'vitamin', 'prothrombin', and 'thrombin'.
Recognize that prothrombin and thrombin are key components of the blood clotting (coagulation) process.
The question asks to link a specific vitamin to this process. This is a factual recall question based on the physiological functions of vitamins.
Systematically review the main functions of the vitamins listed in the options.
Recall that Vitamin K is uniquely associated with the synthesis of blood clotting factors.
Even though the question's phrasing ('convert') is a simplification, Vitamin K is the only plausible answer as it's essential for making prothrombin ready for conversion.

Concept Tested & Keywords

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