Petechial hemorrhages were noticed on the upper and lower extremities of a 5-day-old infant. Hemorrhagic disease of the neonate was most likely caused by a deficiency of which of the following vitamins?: (A) Vitamin B2 (riboflavin), (B) Vitamin D, (C) Folic acid, (D) Vitamin K
Answer is D. Hemorrhagic disease of the new-born may be caused by a deficiency of vitamin K. Vitamin K is an important coagulation factor, which is necessary for the carboxylation and activation of prothrombin, as well as of clotting factors VII, IX, and X. Newborn infants frequently exhibit vitamin K deficiency because the vitamin is not transported well across the placenta, and the sterile gut of the new-born does not have bacteria to produce it. The other vitamin deficiencies do not impair coagulation.Diagnosis: Vitamin K deficiency, hemolytic disease of the newborn