Review Question - QID 204659

This newborn did not receive the standard vitamin K injection at birth and is now presenting with bleeding secondary to a vitamin K deficiency. Vitamin K deficient individuals have reduced levels of specific clotting factors that result in a prolonged Prothrombin time (PT).

Newborns tend to be vitamin K-deficient at birth. This is because vitamin K passes through the placenta poorly resulting in low vitamin K stores, and newborns do not have sufficient gut bacteria to help vitamin K production. For these reasons, the American Academy of Pediatrics universally recommends an intramuscular shot of vitamin K for all newborns within 1 hour of birth. Newborns who do not receive vitamin K after birth are at risk for bleeding from several common sites including mucous membranes, the gastrointestinal tract and the umbilical stump. In patients with vitamin K deficiency, the PT is typically prolonged while the partial thromboplastin time (PTT) is usually normal.

Ballas and Kraut discuss the approach to easy bruising and bleeding. A thorough medical and family history helps guide the work-up along with the physical exam. In cases of suspected bleeding disorders, the following labs are important for initial evaluation: complete blood cell count, peripheral blood smear, PT, PTT. More specialized tests can be helpful in advanced evaluation.

Dituri F et al. examined the use of Proteins Induced by Vitamin K Absence (PIVKA-II) as a means of detecting subclinical vitamin K deficiency in breast-fed newborns. Infants were split into three groups: placebo, inadequate vitamin K supplementation, and adequate vitamin K supplementation. They found that infants receiving placebo and inadequate supplementation had significant increases in the PIVKA-II levels, but patients with adequate supplementation had stable levels of PIVKA.

Illustration A is a schematic of the coagulation pathway, note that the Vitamin K dependent factors are factors II, VII, IX, X as well as protein C and protein S.

Incorrect Answers
Answer 1: Patients with vitamin K deficiency typically have a normal bleeding time.
Answer 3: The PT would be prolonged not normal in this vitamin K deficient patient.
Answers 4 & 5: Platelet counts are typically unaffected by vitamin K deficiency.