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Disorders of Calcium and Phosphorus Metabolism

Key Points Neonatal hypocalcemia may be asymptomatic or present with signs of increased neuromuscular excitability, including focal or generalized seizures. Neonatal hypocalcemia is classified by the timing of onset, with early and late hypocalcemia having different causes and approaches to evaluation. Neonatal hypercalcemia may be asymptomatic if there are only mild elevations in calcium level or may lead to severe symptoms such as failure to thrive,…

Developmental Endocrinology

Key Points Developmental disorders of endocrine organs often manifest themselves in the neonatal period. The fetal adrenal gland produces large amounts of androgens to be used by the placenta for estrogen biosynthesis. Neonatal hypopituitarism may be due to a number of specific gene mutations with or without defects in other cranial structures. The thyroid emerges from the pharyngeal floor and then migrates caudally to its final…

Systemic Hypertension

Key Points There are numerous influences on normal blood pressure (BP) in neonates, including gestational age, birthweight, and maternal factors such as preeclampsia. As in older children, identification of hypertension (HTN) in the neonate is dependent on proper BP measurement technique. While the differential diagnosis of systemic HTN in the neonate is broad, common causes include catheter-related thromboembolic phenomena, chronic lung disease, kidney disease, and iatrogenic…

Urinary Tract Infections and Vesicoureteral Reflux

Key Points The presentation of urinary tract infections (UTIs) in neonates differs from that seen in older children. The type and route of infection also differ in neonates, when compared with older children. An appropriate urine sample for diagnosis is needed, but treatment should not be delayed. A febrile neonate in whom a UTI is suspected should be evaluated for sepsis, including blood and possible spinal…

Glomerulonephropathies and Disorders of Tubular Function

Key Points Nephrotic syndrome (NS) comprises persistent heavy proteinuria, hypoalbuminemia, edema, and hyperlipidemia. Genetic abnormalities of structural or regulatory proteins within the glomerular basement membrane and/or podocyte lead to primary congenital NS (CNS). Treatment of CNS does not involve immunosuppression and is aimed at minimizing symptoms and preventing serious complications. Infections causing secondary NS include human immunodeficiency virus, syphilis, toxoplasmosis, hepatitis B, malaria, rubella, and cytomegalovirus.…

Chronic Kidney Disease

Key Points Kidney development continues until 34 weeks’ gestation. Neonatal intensive care unit graduates, especially those with a history of acute kidney injury (AKI), premature infants, and those with intrauterine growth retardation, are at risk for long-term chronic kidney disease (CKD). Clinical sequelae of CKD include anemia, acidosis, electrolyte abnormality, growth restriction, renal osteodystrophy, fluid overload, hypertension, and uremia. Attention to these complications is critical to…

Acute Kidney Injury

Key Points Acute kidney injury (AKI) is common in critically ill neonates. AKI affects survival, hospital expenditures, and long-term outcomes, independent of the severity of illness and comorbidities. Kidney development continues until 34 weeks’ gestation. Neonatal intensive care unit graduates, especially those with a history of AKI, those born prematurely, and those with intrauterine growth retardation, are at risk for long-term chronic kidney disease. New technological…

Developmental Abnormalities of the Genitourinary System

Key Points A voiding cystourethrogram should be performed in infants with high-grade hydronephrosis or bilateral hydronephrosis. Vesicoureteral reflux is more common in male infants and has a high rate of spontaneous resolution. Bladder exstrophy repairs are currently delayed to 3 months of age and performed with a dedicated team. Nadir creatinine predicts future renal function in posterior urethral valves. Current American Urological Association guidelines do not…

Developmental Abnormalities of the Kidneys

Key Points Kidney malformations account for 20% to 30% of all prenatally diagnosed developmental anomalies and are responsible for 31% of all childhood end-stage kidney disease. Patients with unilateral kidney agenesis are at risk for hypertension in childhood and chronic kidney disease in adulthood. Multicystic dysplastic kidney typically presents as a collection of large kidney cysts on ultrasound, and patients generally do well. Autosomal recessive polycystic…

Renal Development

Key Points Renal organogenesis is a complex interaction between gene stimulation of planned growth and complementary apoptosis, allowing appropriate development of the functioning renal organ system, vascular bed, and intertwined genital system. The renin-angiotensin system (RAS) is critical to normal renal development through delicate interaction between the maternal–placental RAS and the developing fetal RAS, which has central hormone-specific and sex-specific configurations that help the developing vascular…

Congenital Malignant Disorders

Key Points The spectrum of malignancies in neonates differs from that in children. Malignancies in neonates are often associated with a genetic predisposition. Neuroblastoma and leukemia are the most common malignancies in neonates. Cancer treatment in neonates poses unique challenges, including the likelihood of significant late effects. Congenital solid tumors are often diagnosed in utero by ultrasonography. Neonatal malignancies differ in incidence, clinical behavior, and heritable…

Neonatal Hyperbilirubinemia and Kernicterus

Key Points Early clinical jaundice or rapidly developing hyperbilirubinemia is often a sign of hemolysis, the differential diagnosis of which commonly includes immune-mediated disorders, red cell enzyme deficiencies, and red cell membrane defects. Knowledge of the maternal blood type and antibody screen is critical in identifying non-ABO alloantibodies in the maternal serum that may pose a risk for severe hemolytic disease of the newborn. Knowledge of…

Neonatal Leukocyte Physiology and Disorders

Key Points The neonate and the young infant depend primarily on the innate immune system for host defense. With limited prior exposure to infectious and environmental antigens, the adaptive immune arm is still in a phase of structural and functional development. Neutropenia is frequently encountered during the neonatal period. Neonatal neutrophils show a wide range of functional deficiencies in movement, phagocytosis, and microbial killing. With the…

Neonatal Transfusion

Key Points Recent multicenter randomized trials support more conservative transfusion approaches with the use of lower hemoglobin and platelet count thresholds. Two multicenter clinical trials did not show improvement in survival without neurodevelopmental impairment or other important outcomes with the use of higher hemoglobin thresholds for red blood cell transfusion in preterm infants. Given the lack of benefit, these data generally support the use of a…

Neonatal Erythrocyte Disorders

Key Points Erythropoiesis occurs in stages or waves during embryonic development, initiating in the yolk sac, migrating to the liver, and finally to the bone marrow. The sites of erythropoietin production also transition during development from the neuronal cells to the fetal hepatocytes, and ultimately to the renal fibroblasts. Fetal red blood cells (RBCs) have higher mean corpuscular volumes and mean corpuscular hemoglobins, different hemoglobin composition,…

Neonatal Platelet Disorders

Key Points The most common cause of mild to moderate, early-onset thrombocytopenia in well-appearing neonates is placental insufficiency, frequently manifesting as small-for-gestational status at birth. This thrombocytopenia resolves spontaneously, usually within 10 days, and carries good prognosis. Thrombocytopenia in sick infants is usually associated with sepsis or necrotizing enterocolitis (NEC) and requires prompt intervention. Neonates with platelet counts <50 × 10 9 /L in the first…

Neonatal Bleeding and Thrombotic Disorders

Key Points Acquired or inherited coagulation disorders should be considered in any neonate that suffers significant hemorrhage. Treatment for specific coagulation disorders should be provided in consultation with pediatric hematology and based on the most current guidelines. Thromboembolism (TE) is a significant problem affecting both term and preterm neonates. Most neonates that experience a significant TE event have acquired risk factors and/or a prothrombotic disorder. Proper…

Developmental Hematology

Key Points Pluripotential stem cells sustain hematopoietic function throughout a person's lifetime; the fate of developing cells is influenced by the microenvironment. The site of erythropoiesis changes over development, progressing from the yolk sac to the aortogonadomesonephron, to the liver, and then to the bone marrow. Erythropoietin (Epo) is the principal factor regulating secondary erythropoiesis. Hemoglobin tetramers change over development. Oxygen affinity decreases as hemoglobin switches…

Disorders of the Liver

Key Points Early onset (<24 hours of age) or new jaundice is never normal and should be investigated. Initial evaluation of a jaundiced infant should always include conjugated and unconjugated bilirubin levels. Infants presenting with jaundice secondary to conjugated hyperbilirubinemia should undergo expedient evaluation for potentially life-threatening and treatable causes of cholestasis and then for other causes. Neonatal Liver Disease The liver is the largest abdominal…

Necrotizing Enterocolitis and Short Bowel Syndrome

Key Points What we have termed “necrotizing enterocolitis” (NEC) is not a discrete entity but, rather, a manifestation of different forms of intestinal injury that can lead to intestinal necrosis. To make progress in terms of prevention, a better delineation of these forms of injury is critical. The pathophysiology of the classical form of NEC involves an interaction of factors that include an immature bowel and…