pediatrics
Neonatal Hyperbilirubinemia
Evaluation of Neonatal Hyperbilirubinemia
History of present illnessshould note age of onset and duration of jaundice. Important associated symptoms include lethargy and poor feeding (suggesting possible kernicterus), which may progress to stupor, hypotonia, or seizures and eventually to hypertonia. Patterns of feeding can be suggestive of possible breastfeeding failure or underfeeding. Therefore, history should include what the infant is being fed, how much and how frequently, urine and stool production (possible breastfeeding failure or underfeeding), how well the infant is latching on to the breast or taking the nipple of the bottle, whether the mother feels that her milk has come in, and whether the infant is swallowing during feedings and seems satiated after feedings. Review of systemsshould seek symptoms of causes, including respiratory distress, fever, and irritability or lethargy (sepsis); hypotonia and poor feeding (hypothyroidism, metabolic disorder); and repeated episodes of vomiting (intestinal obstruction). Past medical historyshould focus on maternal infections (toxoplasmosis, other pathogens, rubella, cytomegalovirus, and herpes simplex [TORCH] infections), disorders that can cause early hyperbilirubinemia (maternal diabetes), maternal Rh factor and blood group (maternofetal blood group incompatibility), and a history of a prolonged or difficult birth (hematoma or forceps trauma). Family history should note known inherited disorders that can cause jaundice, including glucose-6-phosphate dehydrogenase (G6PD) deficiency, or other red cell enzyme deficiencies, thalassemias, and spherocytosis, and also any history of siblings who have had jaundice. Drug history should specifically note drugs that may promote jaundice (eg,ceftriaxone, sulfonamides [these drugs do not promote jaundice they instead lead to potentially more harm at lower measured bilirubin levels because they displace bilirubin fromalbuminincreasing the free bilirubin fraction], and antimalarials). Overall clinical appearance and vital signs are reviewed. The skin is inspected for extent of jaundice. Gentle pressure on the skin can help reveal the presence of jaundice. The physical examination should focus on signs of causative disorders. The general appearance is inspected for plethora (maternofetal transfusion), macrosomia (maternal diabetes), and lethargy or extreme irritability (sepsis or infection) and for any dysmorphic features such as macroglossia (hypothyroidism) and flat nasal bridge or bilateral epicanthal folds (Down syndrome). For the head and neck examination, any bruising and swelling of the scalp consistent with a cephalohematoma are noted. Lungs are examined for crackles (rales), rhonchi, and decreased breath sounds (pneumonia). The abdomen is examined for distention, mass (hepatosplenomegaly), or pain (intestinal obstruction). Neurologic examination should focus on signs of hypotonia or weakness (metabolic disorder, hypothyroidism, sepsis). The following findings are of particular concern: Jaundice in the first day of life Total serum bilirubin>18 mg/dL (> 308 micromol/L) Rate of rise of total serum bilirubin>0.2 mg/dL/hour (>3.4 micromol/L/hour) or>5 mg/dL/day (> 86 micromol/L/day) Conjugated bilirubin concentration>1 mg/dL (>17 micromol/L) if total serum bilirubin is<5 mg/dL (< 86 micromol/L) or>20% of total serum bilirubin (suggests neonatal cholestasis) Jaundice after 2 weeks of age Lethargy, irritability, respiratory distress Evaluation should focus on distinguishing physiologic from pathologic jaundice. Physical Findings in Neonatal Jaundice can help, but typically total serum bilirubin and conjugated serum bilirubin levels are measured. Jaundice that develops in the first 24 to 48 hours, or that persists>2 weeks, is most likely pathologic. Jaundice that does not become evident until after 2 to 3 days is more consistent with physiologic, breastfeeding, or breast milk jaundice. An exception is undersecretion of bilirubin due to metabolic factors (eg, Crigler-Najjar syndrome, hypothyroidism, drugs), which may take 2 to 3 days to become evident. In such cases, bilirubin typically peaks in the first week, accumulates at a rate of<5 mg/dL/day (< 86 micromol/L), and can remain evident for a prolonged period. Because most neonates are now discharged from the hospital or nursery within 48 hours, many cases of hyperbilirubinemia are detected only after discharge. Diagnosis of hyperbilirubinemia is suspected by the infant’s color and is confirmed by measurement of serum bilirubin. Noninvasive techniques for measuring bilirubin in infants, including transcutaneous and digital photography–based techniques, are being used increasingly and correlate well with serum bilirubin measurements. Risk of hyperbilirubinemia is based on age-specific total serum bilirubin levels. A bilirubin concentration>10 mg/dL (>171 micromol/L) in preterm infants or>18 mg/dL (>308 micromol/L) in term infants warrants additional testing, including hematocrit, blood smear, reticulocyte count, direct Coombs test, total serum bilirubin and direct serum bilirubin concentrations, and blood type and Rh group of the infant and mother. Other tests, such as blood, urine, and cerebrospinal fluid cultures to detect sepsis and measurement of red blood cell enzyme levels to detect unusual causes of hemolysis, may be indicated by the history and physical examination. Such tests also may be indicated for any neonates with an initial bilirubin level>25 mg/dL (>428 micromol/L). 