Vitamin K Deficiency
Vitamin K Deficiency is caused by the insufficient intake of vitamin K.
Causes include insufficient absorption or insufficient production by gut flora. Specifically, Crohn's disease, cystic fibrosis, and other causes of pancreatic insufficiency can lead to poor absorption of this fat-soluble vitamin.
Insufficient production by gut flora is of particular concern in newborns, as their sterile intestines are unable to synthesize vitamin K. This leads to a condition known as hemorrhagic disease of the newborn, which is characterized by increased PT (and PTT) but normal bleeding time. Likewise, prolonged antibiotic use (broad-spectrum) may disturb gut flora, which again may lead to impaired synthesis of vitamin K and subsequent deficiency.
Find Vitamin K Deficiency and other Vitamins among Pixorize's visual mnemonics for the USMLE Step 1 and NBME shelf exams.