A full-term exclusively breastfed infant presents at 5 weeks of age with oozing from the umbilical stump, cephalohematoma, and prolonged PT. Which combination best explains why exclusively breastfed neonates are at particular risk of this condition?

• A Breast milk is rich in vitamin K but the infant's gut flora destroys it
• B Breast milk inhibits absorption of synthetic vitamin K given at birth
• C Maternal antibodies inhibit hepatic gamma-glutamyl carboxylase in the infant
• D Breast milk is low in vitamin K, placental transfer is poor, and the sterile newborn gut synthesizes little menaquinone ✓

Explanation

Classic vitamin K deficiency bleeding of the newborn arises from three converging factors: limited placental transfer of vitamin K, very low vitamin K content of breast milk compared with formula, and a sterile immature gut that produces little bacterially derived menaquinone until colonization occurs. Prophylactic intramuscular vitamin K at birth prevents it. Maternal antibodies and destruction of dietary vitamin K by gut flora are not recognized mechanisms.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.