Weight

A normal neonate may lose up to 10% of birth weight during the first week of life. By the end of the second week, the infant should have returned to birth weight or a little above it. Weight gain from this point through the first month should be about 30 g (1 oz) per day. It is essential that the weight (undressed) of any neonate be measured accurately in the ED.

Feeding

The feeding schedules of neonates are quite variable, and the same child can exhibit significant variability within a 24-hour period. The average neonate eats between six and nine times a day. Intervals between feeding may range from 2 to 4 hours. Breastfed infants tend to eat more often than formula-fed infants.

Sleeping

Newborns sleep 16 to 18 hours per day, with almost equal amounts of day and night sleep. Awake periods are generally about 1 to 2 hours in duration.

Vital Signs

A normal neonatal pulse is in the range of 120 to 160 beats/min, but it rises if the child is stimulated. The heart rate slows during sleep.

The normal respiratory rate is between 40 and 60 breaths/min. Some irregularity and pauses of less than 20 seconds are normal in the neonatal period. Respiratory pauses should not be associated with any change in color or hypotonia. Because of this irregularity in respiratory rate, accurate measurements can be obtained only if breaths are counted for at least 30 seconds.

Measuring blood pressure in a newborn can be frustrating and time-consuming. A Doppler probe can facilitate the procedure. A systolic blood pressure of less than 60 mm Hg is abnormal in a neonate.

The core temperature in an infant is the same as that in an adult. Fever is generally recognized as a temperature higher than 38° C (100.4° F). Any temperature lower than 36.1° C (97° F) should raise concern for hypothermia. Because of limited thermoregulatory ability, neonates should be examined and treated in a warm ambient environment. See Table 15.1 for normal neonatal vital signs.

Table 15.1 Normal Vital Signs in Neonates

Epidemiology

General estimates suggest that between 0.5% and 6.0% of infants will experience an apparent life-threatening event (ALTE). A prospective Austrian study conducted from 1993 to 2001 revealed an incidence of 2.46 per 1000 live births.² In this study more than 60% of the events occurred in infants 2 months or younger.

Pathophysiology

ALTE is not a single disease entity but rather a constellation of signs and symptoms of numerous diseases that can have lethal consequences. The 1986 National Institutes of Health Consensus Development Conference on Infantile Apnea and Home Monitoring defined ALTE as “an episode that is frightening to the observer and is characterized by some combination of apnea (central or occasionally obstructive), change in color (usually cyanotic or pallid, but occasionally erythematous or plethoric), marked change in muscle tone (usually marked limpness), choking, or gagging.”³

The conventional definition of apnea is absence of breathing for 20 seconds or for a shorter period if associated with clinical signs such as cyanosis, hypotonia, and bradycardia. Because periods of apnea of up to 30 seconds have been observed in normal, healthy, asymptomatic term and preterm infants, the duration of apnea does not seem to be as clinically important as apnea associated with signs and symptoms.⁴ Apnea should be distinguished from the normal periodic breathing of newborns, which is characterized by irregular breathing and episodes of pauses. This latter pattern is more commonly seen in premature infants during sleep. Although similarities exist, ALTE is now considered a different pathophysiologic entity from sudden infant death syndrome.

Presenting Signs and Symptoms

The majority of neonates who have experienced an ALTE have a normal appearance at the time of arrival at the ED. Stratton et al. reported a prehospital study of 60 cases of ALTE in which 83% of the infants were asymptomatic by the time that emergency medical service personnel arrived.⁵ A comprehensive history and a thorough physical examination should be performed. One study showed that the history and physical examination were helpful in diagnosing the cause of ALTE in 70% of cases.⁶ The history should consist of a detailed description of the event, a prenatal and perinatal history, a review of systems, and a family history (especially child deaths, neurologic diseases, cardiac diseases, and congenital problems). Box 15.1 lists essential historical questions in these cases. A detailed physical examination should pay particular attention to the neurologic, respiratory, cardiac, and developmental components. Evidence of child abuse should be sought, including a funduscopic examination for retinal hemorrhage.

Differential Diagnosis and Medical Decision Making

ALTEs and apnea are clinical manifestations that have many causes, as summarized in Box 15.2. The most common organ systems involved (in order of decreasing frequency) are the gastrointestinal, neurologic, respiratory, cardiac, metabolic, and endocrine systems. The cause of ALTE in an individual patient is likely to be discovered only about 50% of the time.

Diagnostic testing is best guided by the history and physical examination. Laboratory tests have been shown to be contributory to the diagnosis only 3.3% of the time if the results of the history and physical examination were noncontributory.⁶ An Israeli study concluded that diagnostic testing has low yield in infants with normal perinatal histories and normal findings on physical examination.⁷

Disposition

Historically it has been the practice that all infants with apnea or ALTE be admitted for observation. Some studies suggest that certain low-risk infant groups might be able to be discharged home from the ED.^8,9 Box 15.3 lists low-risk criteria for ALTE. An infant meeting all the criteria in this box would have a very low probability of experiencing an adverse outcome. Otherwise, it is prudent to admit the infant for observation and in-patient evaluation by a pediatric specialist.

Epidemiology

Crying peaks in infancy at 6 weeks of age with an average crying time of 3 hours per day. More of the crying time is clustered in the late afternoon and evening. Forty percent of these infants cry for 30 minutes or longer at one time, 75% of whom have the longest crying spells between 6 and 12 PM.¹⁰ The prevalence of excessive crying varies between 1.5% and 11.9%, depending on the definition of excessive crying.¹¹

Pathophysiology

Crying is a form of communication by the neonate. It signals some form of infant discomfort from hunger to lack of attention to other causes of pain, some that can be serious.

Presenting Signs and Symptoms

Box 15.4 lists important questions to ask the caregiver of an afebrile infant with excessive crying. Table 15.2 lists possible physical findings in these infants.

Table 15.2 Potential Abnormalities in Crying Infants Found on Physical Examination

Differential Diagnosis and Medical Decision Making

The first differentiation that the clinician must make is whether the child is febrile (see the section “Fever”). In an afebrile infant the chronicity of the crying is important. Is the crying an acute single episode, or has it been an ongoing problem for some time?

The latter describes colic, which affects a large subgroup of excessively crying infants. Classically, colic has been described by the rule of threes—crying for 3 hours per day, for at least 3 days per week, for 3 weeks. Scores of theories concerning the etiology of colic have been proposed; such theories range from physiologic disturbances (cow’s milk allergies, gastrointestinal reflux, hypocontractile gallbladder, and other gastrointestinal disturbances), to infant temperament and maternal response, to deficiencies in parenting practices.¹² No single cause has been identified.

No pharmacologic agent has been listed as being both safe and efficacious for the treatment of colic. Anticholinergic agents have been found to be more effective than placebo but are associated with apnea and should not be administered to infants younger than 6 months.¹³ Many other interventions have been proposed for colic, such as having the infant in a car, specific ways to hold the infant, use of white noise, crib vibrators, and herbal teas. None have been shown to be particularly beneficial, however. The EP should reassure parents that there is no ideal treatment of colic, that their child is normal, that the infant will outgrow the colic, and that colic has no long-term sequelae.

A retrospective study involving 237 afebrile children younger than 1 year brought to the ED with the chief complaint of crying or fussiness revealed that 5.1% had a serious underlying etiology. The final diagnosis in the 237 patients was made by the history and physical examination alone in 66% of cases. Only 0.8% of the diagnoses were made by diagnostic evaluation alone. These authors concluded that afebrile crying infants younger than 1 month should undergo urinalysis.¹⁴

A suggested approach to the ED evaluation of an excessively crying child is presented in Figure 15.2.

Fig. 15.2 Evaluation of a crying neonate.

CBC, Complete blood count.

Treatment

Treatment is determined by the underlying condition causing the crying.

Disposition

Afebrile crying infants may be discharged home if they are consolable, if they have a negative history and physical examination, and if the clinician has a low index of suspicion for a “sick” child.

Pathophysiology

Cyanosis is the result of either deoxygenated hemoglobin or abnormal hemoglobin (methemoglobin). Cyanosis occurs with the presence of 4 to 5 g of deoxygenated (unsaturated or reduced) hemoglobin per 100 mL of blood. This is an absolute quantity and not a percentage of unsaturated hemoglobin. A cyanotic, polycythemic infant with a hemoglobin value of 18 g/100 mL might have no tissue hypoxia if the total amount of unsaturated hemoglobin is only 5 g/100 mL because the oxygen content of the blood would still be adequate. Conversely, an anemic infant with a hemoglobin value of 7 g/100 mL would have severe tissue hypoxia because at least 4 to 5 g/100 mL of the total is deoxygenated hemoglobin.

Presenting Signs and Symptoms

Cyanosis in a neonate may be persistent or transient, central or peripheral (acrocyanosis). The EP can best evaluate cyanosis clinically by looking at the tongue and mucous membranes. Duskiness or blueness in these areas defines central cyanosis, a pathologic condition. In peripheral cyanosis, or acrocyanosis, the extremities are blue but the oral mucosa and tongue remain pink; this pattern is frequently a normal finding in a neonate but can be associated with pathologic oxygenation.

Differential Diagnosis and Medical Decision Making

An easy method of classifying cyanosis is by causative organ system (Box 15.5). The cardiac and respiratory systems are responsible for the large majority of cases of neonatal cyanosis. Distinguishing between these two categories can be difficult but is necessary for optimal management of the patient.

An echocardiogram is the most definitive test that can be performed in the ED to distinguish between pulmonary and cardiac causes of cyanosis. If unavailable, the next best test would be the hyperoxia-hyperventilation test (also called the 100% oxygen challenge test), and it is performed as follows:

If the hypoxia is secondary to pulmonary disease, PaO₂ usually rises to greater than 150 mm Hg with 100% oxygen. If the hypoxia is secondary to right-to-left cardiac shunting from congenital heart disease, the Pao₂ value does not rise significantly when the infant is receiving 100% oxygen. Occasionally, enough intrapulmonary right-to-left shunting occurs in lung disease to prevent a rise in PaO₂ with the simple administration of 100% oxygen. In these cases the infant can be manually ventilated with 100% oxygen, and PaO₂ rises if the source of cyanosis is in the lungs. In many instances these results are obtained clinically by the infant’s response to oxygen during the initial resuscitation.

Though rare, methemoglobinemia is a possibility in a cyanotic neonate. This syndrome may be inherited or acquired. The acquired form is typically due to drugs and toxins such as nitrites, anesthetics, and aniline dyes, but it may occur as a result of diarrhea and acidosis.

Treatment

The initial treatment of any neonate with cyanosis includes adequate supplemental oxygenation, ventilation, and an intravascular volume challenge with 10 to 20 mL/kg of normal saline (NS). If no response is seen to volume resuscitation, vasopressor support with dopamine, 5 to 20 mcg/kg/min, should be instituted.

If a cyanotic neonate continues to show signs of inadequate tissue oxygenation after the initial resuscitation, prostaglandin E₁ (alprostadil) should be given intravenously (IV) starting at 0.05 to 0.1 mcg/kg/min. Administration of prostaglandin is frequently associated with apnea, fever, and occasionally shock. The EP should be prepared to intubate the infant if such complications arise. One study has shown that aminophylline given as a 6-mg/kg bolus before the administration of prostaglandin E₁, followed by 2 mg/kg IV every 8 hours for 72 hours, significantly reduces apnea.¹⁵

Acquired methemoglobinemia is treated with methylene blue, 1 to 2 mg/kg IV as a 1% solution delivered over a 5-minute period.

Disposition

An acutely cyanotic infant will require admission to the hospital for evaluation and treatment. An infant with known cyanotic heart disease may be able to be discharged, but discharge should be done only in consultation with the infant’s cardiology specialist.

Pathophysiology

Difficulty breathing may arise from pathology in the heart, lungs, or central and peripheral nervous systems. Toxins and systemic illness, such as sepsis and acidosis, can cause breathing difficulty. Regardless of cause, immediate evaluation is required.

Presenting Signs and Symptoms

Respiratory distress involves a spectrum of clinical findings from apnea, dyspnea, tachypnea, stridor, nasal flaring, grunting, chest retractions, wheezing, and rales to simple nasal congestion and periodic breathing. Tachypnea (fast breathing) should be distinguished from dyspnea (increased work of breathing) because lung pathology is more likely to be associated with dyspnea. Rapid, unlabored respirations are more likely to be seen in neonates with metabolic acidosis and cardiac pathology. Stridor is a symptom of upper airway obstruction from either intrinsic or extrinsic causes.

Differential Diagnosis and Medical Decision Making

A list of potential causes of respiratory distress that can occur anytime during the first 28 days is presented in Box 15.6. The majority of causes are pulmonary, cardiac, or infectious. Diagnostic testing includes a complete blood count, serum glucose measurement, metabolic profile, blood cultures, arterial blood gas measurements, urinalysis, urine culture, chest radiography, and electrocardiography.

The differential diagnosis of pulmonary causes of respiratory distress in a neonate can be divided into syndromes manifested in the first hours of life and those manifested anytime during the first 28 days. The former group includes transient tachypnea of the newborn, respiratory distress syndrome, persistent pulmonary hypertension of the newborn, and meconium aspiration syndrome. These conditions are not discussed further because they are almost certainly diagnosed and treated in the nursery, not the ED.

Pneumonia is the most common and most serious infectious cause of respiratory distress in the first 28 days of life. From a clinical perspective, neonatal pneumonia can be divided into early-onset and late-onset types (Table 15.3).

Table 15.3 Causes of Neonatal Pneumonia

Scope

Fever is defined as a rectal temperature of 38° C (100.4° F) or higher. The majority of febrile illnesses in infants are self-limited viral infections. Ten percent to 20% of febrile infants younger than 3 months have a serious bacterial infection (SBI), defined as bacterial meningitis, bacteremia, urinary tract infection, pneumonia, skin or soft tissue infection, bacterial enteritis, septic arthritis, or osteomyelitis. Bacteremia is twice as likely to occur in the first month of life as in the second month.²⁴

Pathophysiology

A neonate’s immature immune system lacks the ability to localize and contain infection; therefore, the newborn may not show specific signs of serious underlying disease. The birth process exposes the infant to an array of bacterial and viral pathogens. The most common bacterial pathogens in the first 28 days of life are group B streptococci and Escherichia coli. Other bacteria may be gram-negative (e.g., Klebsiella, Enterobacter, Salmonella) or gram-positive organisms (Staphylococcus aureus, Enterococcus, other streptococcal species, and Listeria monocytogenes). Herpes simplex virus and the enteroviruses can also cause febrile illness in neonates. Neonatal herpes can be a devastating illness, with only about half the cases caused by active maternal infection.

Presenting Signs and Symptoms

A febrile neonate may look remarkably well or may be extremely toxic appearing.

Differential Diagnosis and Medical Decision Making

Box 15.8 present a work-up for a febrile infant younger than 28 days.

Recent literature suggests that C-reactive protein levels can predict infection. The limitation to its use is that a period of up to 8 to 10 hours is required for synthesis, so it has a variable range of sensitivity (from 14% to 100%) in the first 24 hours. A cutoff of 70 g/L has been proposed, although it is a nonspecific marker for infection.²⁵ Procalcitonin also deserves mention as a possible marker for SBI. It is the prehormone of calcitonin and increases within 2 hours of an infection. Its sensitivity is 92.6% with a specificity of 97.5% if obtained outside the first 48 hours of life.²⁶

Treatment

Empiric antibiotic treatment of neonatal sepsis consists of either ampicillin and gentamicin or ampicillin and cefotaxime (Boxes 15.9 and 15.10). If neonatal meningitis is suspected, ampicillin and cefotaxime are preferred. Some authorities would add gentamicin as a third antibiotic for suspected meningitis when no organisms are seen on Gram stain of cerebrospinal fluid.²⁷ Herpes simplex virus infection should be strongly considered in febrile infants with seizures and abnormal cerebrospinal fluid results. Skin lesions and abnormal liver function values should further increase suspicion for this disorder. An infant with suspected herpes simplex virus infection should receive acyclovir, 60 mg/kg/day in three divided doses (20 mg/kg per dose). Acyclovir should be continued until the results of herpes simplex virus polymerase chain reaction are negative. Neonates with an identifiable viral infection (e.g., respiratory syncytial virus) have as high as a 7% chance of having a concomitant SBI.^28–31 Therefore, a septic evaluation should be performed in any child 1 to 28 days old with fever despite an identifiable viral infection. Antibiotics should be administered empirically to this group. Febrile neonates should be admitted to the hospital.

Scope

Vomiting is defined as forceful diaphragmatic and abdominal wall contraction with simultaneous relaxation of the stomach, gastroesophageal sphincter, and esophagus and closure of the gastric pylorus. Regurgitation, or “spitting up,” is a nonforceful reflux of milk or gastric contents into the mouth. Regurgitation is generally a benign disorder but can occasionally be associated with gastroesophageal reflux disease and result in serious consequences such as apnea.

Pathophysiology

The appearance of the vomitus is important. Bilious vomit suggests obstruction below the ampulla of Vater. Undigested milk may simply be regurgitation but could be caused by gastrointestinal obstruction above the ampulla of Vater. Bloody vomitus requires a search for upper gastrointestinal bleeding.

Signs and Symptoms

It is important to distinguish between bilious vomiting and nonbilious vomiting. If bilious vomiting is reported, it is assumed to be obstructive and a surgical emergency until proved otherwise. Studies have suggested that 20% to 50% of neonates with bilious emesis within the first week of life have a surgical condition.³²

Differential Diagnosis and Medical Decision Making

Causes of vomiting can be divided into anatomic and nonanatomic categories (Box 15-11).

Volvulus from midgut malrotation can be manifested as a sudden onset of bilious vomiting, duodenal obstruction as a result of obstructing Ladd bands, or intermittent vomiting with failure to thrive. Most neonates with volvulus will appear to be well, but if necrosis of the gut or ischemia has begun, they may appear ill or in shock. Abdominal radiographs should be obtained if obstruction is a concern.

To make the diagnosis of volvulus secondary to midgut malrotation promptly, an upper gastrointestinal contrast-enhanced study is needed. The small intestine will have a “corkscrewing” appearance with the intestine rotated to the right side of the abdomen with midgut volvulus.

In dehydrated and toxic infants, a complete blood count, serum glucose and electrolyte measurements, and a septic evaluation should be performed.

A healthy-appearing infant with vomiting but appropriate weight gain and normal vital signs requires no diagnostic testing.

Treatment

If the infant is moderately or severely dehydrated, 0.9% sodium chloride should be administered IV as a 20-mL/kg bolus. Oral rehydration may be tried in a mildly dehydrated infant. Nasogastric decompression is required for intestinal obstruction. Empiric therapy with ampicillin and gentamicin or ampicillin and cefotaxime should be administered for suspected sepsis.

In midgut malrotation with volvulus, management includes placement of a nasogastric tube, administration of broad-spectrum antibiotics (gentamicin, clindamycin, and ampicillin), and rapid fluid replacement with NS (20-mL/kg bolus) as needed.³³

Follow-Up and Disposition

Infants with regurgitation may be managed as outpatients. Children younger than 28 days with true vomiting should be admitted to the hospital for further evaluation and treatment.

Scope

Diarrhea is defined as an increase in both the number and the looseness or wateriness of stools. Even in the neonatal period, diarrhea tends to be self-limited without significant morbidity.

Differential Diagnosis and Medical Decision Making

Viral infections are common, with rotavirus being the most frequent cause. Other viral causes of diarrhea are enterovirus, enteric adenovirus, and coronavirus. Bacterial diarrhea in neonates is caused by the same organisms found in other age groups, including Salmonella, Shigella, Campylobacter, E. coli, Vibrio, Yersinia, and Clostridium difficile.

Salmonella gastroenteritis is potentially dangerous in neonates because of its association with systemic sepsis. Bacteremia may occur in 30% to 50% of neonates infected with this organism. Diarrhea from Salmonella gastroenteritis is usually watery with mucus and may appear bloody. This organism is an enteroinvasive bacterium (i.e., it invades the intestinal mucosa), so a methylene blue smear of a stool specimen will reveal white blood cells. Necrotizing enterocolitis (NEC) is one of the more dangerous causes of neonatal diarrhea. It is classically seen in premature infants but can occur in term neonates. Its incidence is also higher in infants with congenital heart disease.³⁴ The diarrhea is typically bloody and is associated with other symptoms, such as decreased feeding, vomiting, ileus, and abdominal distention. If not treated, symptoms progress to bradycardia, hypothermia, apnea, hypotension, and death. Diagnostic radiographic findings are pneumatosis intestinalis (air in the bowel wall) and air in the portal vein. Intestinal perforation leads to pneumoperitoneum.

Treatment

Neonates with Salmonella gastroenteritis should be treated with cefotaxime, 50 mg/kg IV every 12 hours. Treatment of NEC involves cessation of oral feeding, nasogastric decompression, intravenous fluids, and antibiotics (ampicillin, cefotaxime, clindamycin).

Follow-Up and Disposition

Neonates with suspected bacterial diarrhea or NEC should be admitted to the hospital.

Epidemiology

In almost all newborns, the bilirubin level reaches 2 to 3 mg/dL in the first few days of life. Neonatal jaundice occurs in up to 60% of term infants in the first week of life. Approximately 2% of newborns will reach levels of total serum bilirubin in excess of 20 mg/dL.

Pathophysiology

Hemoglobin degrades to form unconjugated bilirubin. This unconjugated (indirect) bilirubin is lipid soluble and binds to albumin. The bilirubin that is not bound to albumin can cross the blood-brain barrier and injure the brain (kernicterus). Albumin-bound unconjugated bilirubin is transported to the liver and converted to water-soluble conjugated bilirubin (direct bilirubin). Conjugated bilirubin is excreted into bile and then into the gut. Most bilirubin is eliminated from the gut in stool.

Signs and Symptoms

Jaundice is most easily detected in the sclera, skin, and oral cavity.

Differential Diagnosis and Medical Decision Making

Jaundice can be normal (physiologic) or abnormal (nonphysiologic). Physiologic jaundice usually becomes visible on the second or third day of life. Jaundice in the first 24 hours of life is always abnormal. Physiologic jaundice is thought to be secondary to the higher breakdown of red blood cells in neonates and transient slowing of conjugation processes in the liver. It peaks at levels between 5 and 12 mg/dL on the third or fourth day of life and then starts to decline. Risk factors for higher levels of physiologic hyperbilirubinemia include a family history of neonatal jaundice, breastfeeding, bruising and cephalohematoma, maternal age older than 25 years, Asian ethnicity, prematurity, weight loss, and delayed bowel movement. Box 15.12 lists the criteria for physiologic jaundice.

Breast milk jaundice develops after the seventh day of life and peaks during the second or third week. It is postulated that a glucuronidase in breast milk causes increased enterohepatic absorption of unconjugated bilirubin. Because of its late onset, breast milk jaundice is almost never a neurologic threat.

Laboratory tests are indicated in a jaundiced infant unless the EP is absolutely certain that the jaundice is physiologic. A total serum bilirubin measurement with direct and indirect fractions and a complete blood count are required. A Coombs test for autoimmune hemolysis is indicated if the maternal blood type is Rh negative and the infant’s blood type is Rh positive or if the maternal blood type is O and the fetal blood type is A, B, or AB. A reticulocyte count is useful for evaluating hemolytic anemia. Because jaundice can be the initial manifestation of hypothyroidism, measurements of serum thyroid-stimulating hormone and thyroxine may be helpful. If the neonate appears ill—has lethargy, decreased feeding, temperature instability, or difficulty breathing—an evaluation for sepsis is indicated.

Treatment

Early treatment of hyperbilirubinemia ensures adequate hydration and feeding. A breastfed infant should be fed more often to promote stooling and excretion of bilirubin. Further management of hyperbilirubinemia may involve phototherapy or exchange transfusion. Initiation of these therapies depends on several factors, including the total serum bilirubin level and the infant’s birth weight and age. Some preterm infants are at higher risk for neurologic sequelae, which mandates a lower threshold for initiation of phototherapy.

The American Academy of Pediatrics (AAP) has issued practice guidelines for the treatment of neonatal jaundice.³⁵ One tool that the EP may find helpful is the website www.bilitool.org, in which parameters may be entered to determine the infant’s risk based on the bilirubin level obtained. The following information is needed to estimate an infant’s risk: (1) the infant’s date of birth and time (to the hour), (2) the infant’s gestational age, and (3) the time that the bilirubin level was obtained. After entering this information, the AAP guidelines will be listed and appropriate therapy recommendations will be displayed based on the level of risk.

Disposition and Follow-Up

Only well-appearing neonates with clearly physiologic or breastmilk jaundice and a serum bilirubin level below the guideline limits for phototherapy should be discharged. Close follow-up and monitoring should be arranged for such infants at the time of discharge. All other infants should be admitted for further testing and treatment.

Scope

Metabolic emergencies account for a small percentage of disorders in neonates seen in the ED. This low incidence accounts for the difficulty recognizing and treating these emergencies. Adrenal insufficiency is one metabolic emergency in neonates that can be encountered in the ED and should be taken into consideration to reduce an infant’s morbidity and mortality.³⁶

Pathophysiology

Congenital adrenal hyperplasia (CAH) is the most recognized form of adrenal insufficiency in children and is sometimes identified as part of the initial newborn screening program. It is most commonly associated with the lack of 21-hydroxylase, an enzyme necessary for cholesterol metabolism and required to produce cortisol. This may result in virilization of females and be accompanied by an acute salt-wasting crisis. The male genitalia is not generally affected by CAH, thus making males more susceptible to underdiagnosis.

Presenting Signs and Symptoms

Dehydration, hypotension, hypoglycemia, and shock are the most common signs seen in the ED. Neonates may also have fatigue, nausea, vomiting, or weight loss. Females may have an enlarged clitoris and fusion of the labial folds, and some females may be mistaken for males. This makes physical examination extremely important for this diagnosis, and close attention should be paid to the infant, with removal of the diaper and inspection of the genital area. The triad of hyponatremia, hyperkalemia, and hypoglycemia should alert the clinician to this possible diagnosis.

Treatment

The first step is to restore volume with 0.9% NS in 20-mL/kg boluses. Following initial volume replacement, is administered at 1 to times the maintenance rate. Cortisol replacement should be achieved by administration of hydrocortisone, 1 to 2 mg/kg IV for term infants and then 25 to 100 mg/m²/day divided into three to four doses every 6 to 8 hours. Hyperkalemia is typically well tolerated and saline is usually all that is needed to lower the potassium level. Intravenous calcium gluconate, β-agonists, insulin, and glucose should be available for any potential cardiac arrhythmias.³⁷