Clinical Judgment: Endocrine, Hematologic, Gastrointestinal, Renal, and Integumentary
Endocrine
Screen glucose in at-risk infants (preterm, small or large for gestational age, infant of a diabetic mother). Treat symptomatic or very low glucose with 10% dextrose 2 mL/kg IV followed by a continuous infusion; asymptomatic mild lows often respond to feeding. Hypocalcemia (total under 7 mg/dL) is common in preterm and diabetic-mother infants. Congenital adrenal hyperplasia from 21-hydroxylase deficiency presents with ambiguous genitalia, hyponatremia, hyperkalemia, and shock at 1–3 weeks; treat with saline and hydrocortisone.
Hematologic
Physiologic anemia nadirs at 8–12 weeks. Polycythemia (hematocrit above 65%) risks hyperviscosity; partial exchange may be indicated. Jaundice is plotted on hour-specific nomograms - gestational age, hours of life, and risk factors decide phototherapy; exchange transfusion is for severe or rapidly rising levels or any sign of acute bilirubin encephalopathy. Give vitamin K at birth; never skip it.
Gastrointestinal
Necrotizing enterocolitis: feeding intolerance, bloody stool, abdominal distention, pneumatosis intestinalis - stop feeds, decompress, give antibiotics. Bilious emesis is a surgical emergency until malrotation with volvulus is excluded. Pyloric stenosis presents at 3–6 weeks with projectile nonbilious emesis and an olive-shaped mass.
Renal
Oliguria is under 1 mL/kg/hour. Renal vein thrombosis - flank mass, hematuria, thrombocytopenia - is associated with infants of diabetic mothers. Hypospadias is a reason to defer circumcision.
Integumentary
Preterm skin is thin and easily stripped; limit adhesives and bathing. Vesicles in a neonate mean herpes until proven otherwise - culture and start acyclovir.
Rule of thumb
Bilious emesis in any neonate is a surgical emergency; hypoglycemia in a symptomatic infant is treated with IV dextrose, not a bottle.