UKMLA PLAB AMC USMLE Prometric MCQ

a) Vitamin A
b) Vitamin D2
c) alpha-Tocopherol
d) Vitamin K
e) Vitamin C

Correct Answer: D

Explanation:
Manifestations of Vitamin K deficiency include hypoprothrombinemia ,hemorrhaagic diathesis, an increased tendency to bleeding and a prolonged coagulation time. Vitamin K is required for gamma-carboxylation of glutamic acid residues of the procoagulant Factors II (prothrombin), VII, IX, and X and the anticoagulant factors protein C and protein SSevere vitamin K deficiency can lead to a hemorrhagic diathesis that is characterized by prolongations of the PT and sometimes also the aPTT.

The PT is more sensitive than the aPTT in detecting vitamin K deficiency states because Factor VII, the only one of the vitamin K-dependent factors that is in the extrinsic pathway of coagulation, is the most labile of these proteins.The two major sources of vitamin K are dietary intake and synthesis by the bacterial flora of the intestine.

Therefore, in the absence of malabsorption, nutritional deficiency alone rarely causes clinically significant vitamin K deficiency. However, such a condition can arise when eradication of gut flora is combined with inadequate dietary intake. This situation typically occurs in critically ill patients in intensive care units who have no oral intake and are receiving broad-spectrum antibiotics for prolonged periods.

Vitamin K deficiency can also develop in patients receiving total parenteral nutrition unless the infusions are supplemented with vitamin K

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