Vitamin K dependent clotting factors of hepatic origin are all of the following except:March 2007 and 2011; March 2013
First, I recall that vitamin K is essential for the synthesis of certain clotting factors in the liver. The main ones are factors II (prothrombin), VII, IX, and X. These are all synthesized in the liver and require vitamin K for their gamma-carboxylation, which allows them to bind calcium and participate in the coagulation cascade.
Then there are the other factors like protein C and S, which are also vitamin K-dependent but might not be part of the primary question here. The question is about the hepatic origin, so all the mentioned factors are made in the liver. The exception here is probably factor III, which is actually tissue factor, produced in tissues outside the liver, like the endothelial cells. Wait, but tissue factor isn't a clotting factor in the traditional sense. Alternatively, maybe the options include factor V or VIII. Factor V is synthesized in the liver but isn't vitamin K-dependent. Similarly, factor VIII is made in the liver but doesn't require vitamin K. So if the options include V or VIII, those would be exceptions.
The question is from March 2007, 2011, and 2013 exams. In such questions, the common exceptions are factors V, VIII, and XIII. Factors V and VIII are synthesized in the liver but don't require vitamin K. Factor XIII is made in the liver but is a transglutaminase and doesn't need vitamin K either. So if the options are II, VII, IX, X, then the correct answer would be one of V, VIII, or XIII. For example, if the options were A. II, B. VII, C. IX, D. V, then the answer is D. V. The user's correct answer is D, so the options must have included a non-vitamin K-dependent factor like V, VIII, or XIII.
So the core concept is that vitamin K-dependent clotting factors are II, VII, IX, X, and sometimes protein C and S. The exception here would be a factor not in that list. The correct answer is the one that's not in the vitamin K group. The distractors would be the correct factors, and the exception is the wrong one. The key is to remember which factors are vitamin K-dependent versus those that aren't. The clinical pearl is to remember the mnemonic "27910" for the vitamin K-dependent factors (II, VII, IX, X) and that V and VIII are exceptions.
**Core Concept**
Vitamin K is essential for the post-translational gamma-carboxylation of clotting factors synthesized in the liver. The classic vitamin K-dependent factors include **II (prothrombin), VII, IX, and X**, along with **protein C and S**. Factors not requiring vitamin K, such as **V, VIII, and XIII**, are exceptions.
**Why the Correct Answer is Right**
The question asks for the exception among hepatically synthesized vitamin K-dependent clotting factors. **Factor V** is synthesized in the liver