College Answer

1) Liver dysfunction due to alcoholic or viral liver disease.
2) Vit K deficiency
3) Patient on warfarin therapy.

Discussion

The question really asks, "What differen reasons could here be for an isolated PT elevation".

In a guy who is vomiting blood, alcoholism and liver disease are high up on the list.

An isolated PT elevation could be caused by:

• Vitamin K deficiency
  • Malabsorption (leading to vitamin K deficiency)
• Vitamin K antagonists e.g. warfarin, phenindione, rodenticides
• Liver disease
• Isolated Factor VII deficiency

The whole spectrum of abnormal coagulation studies is discussed in greater detail elsewhere.