A 2-day-old boy delivered at home without routine newborn prophylaxis presents with oozing from the umbilical stump and melena. Vital signs show HR 145 bpm, RR 48/min, BP 58/38 mmHg, temperature 37.2°C. Physical examination reveals no hepatosplenomegaly or petechiae. Laboratory studies show PT 22 seconds (normal 12-14) with normal platelet count and bleeding time. Which of the following biochemical processes is most likely impaired?
- A)Activation of plasmin from plasminogen
- B)Gamma carboxylation of glutamate residues on clotting factorsGABARITO
- C)Hydroxylation of proline residues in collagen
- D)Conversion of homocysteine to methionine
- E)Synthesis of platelet thromboxane A2
Explicação
Newborns are relatively vitamin K deficient because of low placental transfer and a sterile gut, and they require prophylaxis at birth. Vitamin K is necessary for gamma carboxylation of glutamate residues on factors II, VII, IX, X, protein C, and protein S. Fa... Ver explicação completa e trilha adaptativa →