A 5-week-old boy is brought to the emergency department after having tonic-clonic movements of his left upper and lower extremity that lasted approximately 3 minutes. The patient was born at home at 38 weeks gestation to a 23-year-old primigravida. The patient's mother received prenatal care, took prenatal vitamins, and had a healthy diet during pregnancy. The infant's newborn screen was positive for cystic fibrosis, and confirmatory testing is pending. The infant has been breastfeeding and gaining weight well. He has never taken any medications and also has received no vaccinations. On examination, the infant is postictal but no longer seizing. A head CT scan shows a right-sided intracranial hemorrhage. Which of the following is the most likely cause of this infant's presentation?

Question

A 5-week-old boy is brought to the emergency department after having tonic-clonic movements of his left upper and lower extremity that lasted approximately 3 minutes.  The patient was born at home at 38 weeks gestation to a 23-year-old primigravida.  The patient's mother received prenatal care, took prenatal vitamins, and had a healthy diet during pregnancy.  The infant's newborn screen was positive for cystic fibrosis, and confirmatory testing is pending.  The infant has been breastfeeding and gaining weight well.  He has never taken any medications and also has received no vaccinations.  On examination, the infant is postictal but no longer seizing.  A head CT scan shows a right-sided intracranial hemorrhage.  Which of the following is the most likely cause of this infant's presentation?

Quizplus · Accepted Answer

11ec160b_3963_8ef6_9249_7301508573f1_MD0001_00 Vitamin K, a fat-soluble vitamin, is an essential cofactor for gamma-glutamyl carboxylase, an enzyme that carboxylates coagulation factors II, VII, IX, and X. Infants are born with low vitamin K stores due to poor transplacental transfer. Their livers are unable to use vitamin K efficiently and breast milk is low in this vitamin. Additional risk factors for neonatal vitamin K deficiency include parental refusal of vitamin K prophylaxis at birth and exclusive breastfeeding. Patients with cystic fibrosis (CF) are also at risk for vitamin K deficiency due to malabsorption of fat-soluble vitamins. Vitamin K deficiency can result in a life-threatening bleeding diathesis, such as intracranial hemorrhage and profuse bleeding from the gastrointestinal tract, umbilicus, and surgical sites. Deficiency is prevented by intramuscular supplementation at birth. (Choice A) Vitamin C (ascorbic acid) deficiency results in defective collagen synthesis due to failure of hydroxylation of proline and lysine. Mucosal bleeding and bruising are typical manifestations in severely malnourished individuals and those who misuse drugs or alcohol. However, breast milk provides adequate ascorbic acid. (Choice B) Vitamin B3 (niacin) deficiency results in failure of formation of nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are required for fatty acid oxidation and synthesis, respectively. Niacin deficiency presents with pellagra (ie, dermatitis, diarrhea, and dementia). (Choices C and F) Patients with CF are at risk for deficiency of both vitamins A and D. Reduced activation of intranuclear receptors occurs in vitamin D deficiency, and exclusively breastfed infants require vitamin D supplementation to prevent hypocalcemia and rickets due to the low content of this vitamin in breast milk. Vitamin A deficiency impairs rhodopsin formation and leads to night blindness and xerophthalmia. (Choice E) Erythropoiesis requires folate, and deficiency leads to megaloblastic anemia. Educational objective: Vitamin K is necessary for the carboxylation and functionality of coagulation factors II, VII, IX, and X. Newborns who do not receive prophylactic supplementation are at risk for bleeding complications. Patients with cystic fibrosis are also at risk for vitamin K deficiency due to poor absorption of fat-soluble vitamins. __________ References: Rise in late onset vitamin K deficiency bleeding in young infants because of omission or refusal of prophylaxis at birth. (http://www.ncbi.nlm.nih.gov/pubmed/24842255) Vitamin K deficiency bleeding: a case study. (http://www.ncbi.nlm.nih.gov/pubmed/24300958)

A 5-Week-Old Boy Is Brought to the Emergency Department After