Definition (Pediatr Rev 1989;11:117)
• ADA: <70 mg/dL for diabetics; <45 mg/dL for everyone else
• Sx: Autonomic, neurologic, behavioral changes: Perspiration, tachycardia, pallor, paresthesia, tremor, weak, N/V, irritability
Pathophysiology
• Nml fall in glucose → ↓ insulin secretion and ↑ counterregulatory hormones
• Presence of insulin inhibits adipose tissue breakdown → no ketones
Etiology
• Decreased availability (production/intake) or increased utilization
• Increased glucose use: Hyperthermia, polycythemia, sepsis, inability to produce/use other energy substrates like FFA, ketones, hyperinsulinemia
• Decreased glycogenolysis, gluconeogenesis, use of alternative fuels
• Inborn errors in metabolism: AA and organic acid d/o (Maple syrup urine dz, etc., G6PD, FAO defects, galactosemia (very rare)
• Liver disease: Hepatitis, Reye’s syndrome, cirrhosis
• Abnormalities in counterregulatory hormones: GHD, adrenal insufficiency
• Neonatal: Prematurity (limited stores), infant of diabetic mother, PPHN
• Hyperinsulinism
• Congenital hyperinsulinism (infants are often LGA)
• PHHN: Persistent hyperinsulinemic hypoglycemia of newborn-genetic eval for common mutations in K channels, or in glutamate dehydrogenase (hyperinsulinism hyperammonemia syndrome)
• Beckwith–Wiedemann
• Drug induced: Insulin (low serum C-peptide—fragment of proinsulin released during secretory process—not found in pharma insulin), oral hypoglycemic agents
• Infant of a diabetic mother
• Tox/drugs: Ethanol, INH, insulin, propranolol, oral hypoglycemics, rat poison (vacor)
• Factitious: Münchhausen syndrome by proxy
Clinical Manifestations
• >2 mo w/ rapid ↓ glucose <40 (often postprandial) usually w/ hunger and adrenergic surge w/ tachycardia, diaphoresis, anxiety, weakness
• Fasting hypoglycemia usually w/ neuroglycopenic symptoms; HA, confusion, fatigue, abn behavior, mental slowness, seizure → coma
• Neonates w/ nonspecific sx; tremor, jitteriness, apnea, cyanosis, hypotonia, poor feeding, tachycardia, cyanosis, seizure → coma
Diagnostic Studies and Management
• Fingerstick glucose can underestimate serum glucose, check venous but treat
• Critical sample = labs to be drawn during hypoglycemic episode: Insulin, cortisol, GH, lactate, pyruvate, beta-OH butyrate, FFA (critical sample) (urine organic acids, acylcarnitine panel, NH3: Can be drawn separately)
• Urine ketones: Absence of ketones → hyperinsulinemia, FAO defect, adrenal insufficiency
• Newborn screen: Aminoacidemias, urea cycle d/o, organic acidurias, FAO d/o
• Management w/ PO or IV glucose (1 cc/kg D25 bolus, then D10 at 1.5 maintenance); calculate GIR (glucose utiliz rate); %dextr × IVF rate/wt (kg) × 6
Use: Diazoxide for hyperinsulinism, then octreotide consider rapid eval, surgical rx at appropriate center if med Rx unsuccessful.