Pediatric emergency medicine trisk 1457 1457
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may reveal leukocytosis and/or thrombocytosis. CSF usually shows a pleocytosis,
with a lymphocytic predominance. Sterile pyuria is sometimes noted. In some
cases of Kawasaki disease, findings consistent with myocardial ischemia or an
arrhythmia may be noted on ECG, and coronary artery aneurysms may be
discovered with an echocardiogram.
Endocrine Disorders (See Chapter 89 Endocrine
Emergencies )
Infants with congenital adrenal hyperplasia (CAH) usually present in the first
few weeks of life with a history of vomiting, lethargy, or irritability. Signs of
marked dehydration may be present with tachycardia and possibly hypothermia.
History may reveal that these infants have been poor feeders since birth and the
symptoms may be progressive over a few days. The physical examination can be
helpful in females if ambiguous genitalia are noted. The presence of marked
hyponatremia with severe hyperkalemia on laboratory evaluation suggests CAH.
Other findings in this disorder include hypoglycemia and metabolic acidosis.
Evaluate for peaked T waves or arrhythmias on ECG as hyperkalemia may result
in sudden cardiac arrest. Elevated 17-hydroxyprogesterone and renin, with
decreased serum aldosterone and cortisol, confirm the diagnosis of CAH.
Metabolic Disorders
Prolonged diarrhea or vomiting can produce hypoglycemia, dehydration,
electrolyte disturbances, and acid–base abnormalities such that an infant will
appear quite ill. Young infants with diarrhea may develop marked hyponatremia
caused by sodium losses or iatrogenic water intoxication. The latter occurs when
well-meaning parents feed excess free water or improperly mix concentrated
formula, leading to a rapid drop in serum sodium. Such infants may appear
lethargic, with slow respirations, hypothermia, and, possibly, seizures that are
difficult to control. Likewise, dehydrated infants with hypernatremia may be
lethargic or irritable, with muscle weakness, seizures, or coma. Persistent
vomiting may lead to hypochloremic alkalosis with hypokalemia, causing
weakness or cardiac dysfunction (see Chapters 22 Dehydration and 100 Renal
and Electrolyte Emergencies ).
A special cause of hyponatremic dehydration to consider is cystic fibrosis .
Vague symptoms in the history include poor feeding, poor growth, and increased
lethargy. The parents may report that the infant gets ill in hot weather and that the
baby’s skin tastes salty. The baby may have also had meconium plug syndrome
(transient distal colonic obstruction caused by inspissated meconium), prolonged
jaundice, or prior pulmonary symptoms such as cough, tachypnea, or pneumonia.
