A 6-hour-old girl is evaluated in the newborn nursery due to respiratory distress. She was born at 37 weeks gestation via spontaneous vaginal delivery after induction of labor for preeclampsia with severe features. Since birth, the baby has not been able to feed due to tachypnea. Birth weight is at

Question

A 6-hour-old girl is evaluated in the newborn nursery due to respiratory distress.  She was born at 37 weeks gestation via spontaneous vaginal delivery after induction of labor for preeclampsia with severe features.  Since birth, the baby has not been able to feed due to tachypnea.  Birth weight is at <3rd percentile for gestational age.  Temperature is 37.2 C (99 F) and blood pressure is normal.  Pulse oximetry is 96% saturation on room air.  Examination reveals a plethoric infant.  The head is normocephalic with an open and flat anterior fontanelle.  Cardiac examination reveals sinus tachycardia and no murmurs.  Pulmonary examination reveals tachypnea; breath sounds are clear throughout, and there are no retractions.  The infant has normal female infantile genitalia.  Chest x-ray shows clear lung fields and a normal cardiac silhouette.  Laboratory results are as follows:  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

11ec25c8_d6a8_b4a1_bc81_f74bbf5cc43b_MD0003_00 Polycythemia is defined as a hematocrit level >65% (>2 standard deviations above the mean) in term neonates. Causes include excessive transfusion (eg, delayed umbilical cord clamping, twin-to-twin transfusion syndrome), intrauterine hypoxia (eg, poor placentation due to maternal diabetes or hypertension, smoking), or genetic conditions (eg, trisomy 21). In this patient, maternal preeclampsia caused placental dysfunction, resulting in intrauterine hypoxia and growth restriction. Other than a ruddy/plethoric appearance, most neonates with polycythemia are asymptomatic. As the hematocrit level rises due to postbirth fluid shifts, the increased blood viscosity may cause decreased blood flow to organs. Common consequences include lethargy, irritability, and jitteriness. Severe symptoms include respiratory distress, tachypnea, poor feeding, and cyanosis. The increased red blood cell mass can lead to hypoglycemia and hypocalcemia due to increased cellular uptake. Treatment of polycythemia is hydration by oral feeds or glucose-containing parenteral fluids. (Choice A) Classic congenital adrenal hyperplasia is caused by 21-hydroxylase deficiency and can cause hypoglycemia and ambiguous genitalia in girls. Other findings include dehydration, hyponatremia, hyperkalemia, and virilization. It does not cause polycythemia, and this infant has normal female genitalia. (Choice B) Congenital cyanotic heart disease can present with cyanosis in newborns, even without murmurs (eg, transposition of the great vessels). This infant's normal cardiac silhouette and normal auscultation, in the presence of high hematocrit, make polycythemia the most likely diagnosis. (Choice C) Dehydration can cause elevated hematocrit levels due to hemoconcentration. However, in the first 2 days of life, dehydration is rare in term neonates, as they are born with excess extracellular water. (Choice D) Glycogen storage disease (GSD) type I, or von Gierke disease, is the most common GSD and presents with hypoglycemia in newborns. Affected infants also have hepatomegaly and severe acidosis. Polycythemia is not associated with GSD. (Choice F) Transient tachypnea of the newborn is a common cause of respiratory distress in term neonates. Chest x-ray will show increased pulmonary vascular markings or fluid in the fissures. In contrast, infants with polycythemia have normal x-rays because the total fluid volume in the lungs is normal. Educational objective: Polycythemia is defined as a hematocrit level >65% in term neonates. Risk factors include excessive transfusion, intrauterine hypoxia, and maternal diabetes. High blood viscosity limits organ perfusion and can cause respiratory distress, hypoglycemia, and poor feeding. References: Restrictive management of neonatal polycythemia. (http://www.ncbi.nlm.nih.gov/pubmed/21667428) Management of polycythemia in neonates. (http://www.ncbi.nlm.nih.gov/pubmed/20725868)

A 6-Hour-Old Girl Is Evaluated in the Newborn Nursery Due