Hypoglycemia

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Hypoglycemia Basics - Sugar Lowdown

  • Definition: Plasma glucose < 45-50 mg/dL (or 2.5-2.8 mmol/L) in neonates, infants, children. Can be symptomatic or asymptomatic.
  • Classification:
    • Transient Neonatal: Common; e.g., Intrauterine Growth Retardation (IUGR), Infant of Diabetic Mother (IDM), perinatal stress (asphyxia, sepsis, hypothermia).
    • Persistent: Concerning; e.g., Hyperinsulinemic hypoglycemia (most common cause in infancy), hormonal deficiencies (GH, cortisol, glucagon), Inborn Errors of Metabolism (IEMs), ketotic hypoglycemia (most common cause >1 year).

⭐ Whipple's triad (symptoms of hypoglycemia, low plasma glucose, relief of symptoms after glucose administration) is key for diagnosing symptomatic hypoglycemia.

Causes Unwrapped - The Why Low?

  • Hyperinsulinism (↑ Insulin)
    • Congenital Hyperinsulinism (e.g., PHHI)

      ⭐ Persistent Hyperinsulinemic Hypoglycemia of Infancy (PHHI) is the most common cause of recurrent, severe hypoglycemia in neonates and young infants.

    • Infant of Diabetic Mother (IDM) - transient
    • Beckwith-Wiedemann Syndrome
    • Insulinoma (rare in children)
    • Sulfonylurea exposure (accidental)
  • Decreased Glucose Production/Substrate (↓ Output)
    • Glycogen Storage Diseases (GSD): Type I, III, VI, IX
    • Fatty Acid Oxidation (FAO) defects
    • Ketotic hypoglycemia (common 1-5 yrs, diagnosis of exclusion)
    • Hormonal: Adrenal insufficiency (cortisol), GH deficiency
    • Prematurity/IUGR (↓ glycogen stores)
    • Severe liver disease
  • Increased Glucose Utilization (↑ Demand)
    • Sepsis, severe infections
    • Burns, shock, perinatal asphyxia
    • Large for Gestational Age (LGA) infants (transient fetal hyperinsulinism)
  • Drugs/Toxins
    • Insulin, oral hypoglycemics (e.g., sulfonylureas)
    • Beta-blockers (e.g., propranolol)
    • Alcohol, Salicylates (high dose) Mind map of inborn metabolic errors causing hypoglycemia

Signs & Sleuthing - Spotting the Dip

  • Clinical Clues: Vary by age & mechanism.

    • Neonates: Jitteriness, apnea, hypotonia, poor feeding, seizures.
    • Older Children:
      TypeSymptoms
      NeurogenicSweating, pallor, tremors, tachycardia, anxiety
      NeuroglycopenicLethargy, confusion, seizures, coma, irritability
  • Diagnostic Gold: The 'Critical Sample'

    • Collect DURING hypoglycemia (BG <50 mg/dL or <2.8 mmol/L).
    • Key analytes: Glucose, Insulin, C-peptide, GH, Cortisol, Lactate, Ketones (BHOB), FFA.
    • Also: Acylcarnitine profile, urine organic acids/ketones.
    • Hypoglycemia Critical Sample Analysis
  • Interpreting Critical Sample:

  • Provocative Tests:

    • Fasting Study: If no spontaneous event; monitor glucose, ketones, insulin.
    • Glucagon Stimulation Test: (e.g., 1mg IM/IV) Glucose rise >25-30 mg/dL suggests adequate glycogen. Blunted in hyperinsulinism.

⭐ In hyperinsulinemic hypoglycemia, ketones are inappropriately low or absent during a hypoglycemic episode.

Fixing the Low - Sweet Solutions

  • Acute Management:
    • Prioritize ABCs; secure IV access.
    • Rapid Correction:
      • IV: 2 ml/kg D10W bolus, then Glucose Infusion Rate (GIR) 6-8 mg/kg/min.
        • $GIR (mg/kg/min) = (% Dextrose \times IV rate (ml/hr)) / (6 \times Wt (kg))$
      • No IV access: Glucagon 0.03-0.1 mg/kg IM/SC/IV (max 1mg).
      • Conscious & cooperative: Oral glucose (juice, gel).
  • Long-term Management (Etiology-Specific):
    • Hyperinsulinism: Diazoxide, Octreotide, Nifedipine; surgery if refractory.
    • Glycogen Storage Diseases (GSD): Regular uncooked cornstarch.
    • Hormonal Deficiencies (GH, Cortisol): Specific hormone replacement.
    • Ketotic Hypoglycemia: Frequent small high-carb/protein feeds; bedtime cornstarch.
  • Monitoring & Prevention: Regular glucose monitoring; educate on signs, prevent recurrence.

⭐ The 'Rule of 50' for initial correction in neonates: 2 ml/kg of D10W (10% Dextrose in Water) provides 200 mg/kg of glucose.

High‑Yield Points - ⚡ Biggest Takeaways

  • Neonatal hypoglycemia: Blood glucose < 45 mg/dL; common in IDM, prematurity, IUGR, sepsis.
  • Whipple's Triad: Symptoms, low glucose, relief with glucose administration.
  • PHHI (Congenital Hyperinsulinism): Most common cause of persistent hypoglycemia in infants.
  • Ketotic Hypoglycemia: Most common in toddlers (18 months-5 years), triggered by fasting/illness.
  • Critical Samples: Collect before glucose for insulin, C-peptide, GH, cortisol, ketones.
  • Management: Oral glucose if conscious; IV Dextrose if severe; Glucagon for emergency_.

Practice Questions: Hypoglycemia

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