Interactive Clinical Guide

Ketotic Hypoglycemia in Pediatrics

What is Ketotic Hypoglycemia?

Idiopathic ketotic hypoglycemia is the most common cause of hypoglycemia in children between 18 months and 5 years. It is characterized by a triad of hypoglycemia, ketonemia and ketonuria after a prolonged period of fasting, often precipitated by an intercurrent illness (e.g. gastroenteritis).

Pathophysiologically, it is due to an intolerance to fasting. Liver glycogen stores are rapidly depleted, activating lipolysis and ketogenesis as an alternative energy source, but this mechanism is insufficient to maintain euglycemia.

Diagnostic Criteria

The diagnosis is fundamentally clinical and exclusionary. It is based on:

  • Documented episode of hypoglycemia: Venous blood glucose < 50 mg/dL (2.8 mmol/L) with neuroglycopenic symptoms (lethargy, irritability, seizures).
  • Ketonuria and/or significant ketonemia: Ketones in urine (++) or more, and/or beta-hydroxybutyrate in blood > 2-3 mmol/L.
  • Rapid clinical response to glucose administration.
  • History of prolonged fasting or decreased intake due to illness.
  • Exclusion of other causes: Absence of hepatomegaly, severe lactic acidosis or data suggesting endocrinopathies (cortisol deficiency, GH) or inborn errors of metabolism.

Management in Emergencies

1. Immediate Measurements (ABCDE) and Critical Sample Collection

Ensure airway and ventilation. Channel a peripheral venous line. Before administering glucose, if possible, remove a "critical sample" for further studies (glucose, insulin, cortisol, GH, beta-hydroxybutyrate, lactate, ammonium, metabolic profile).

2. Pharmacological Treatment

IV Glucose Bolus (Choice)

  • Dose: 0.25 g/kg glucose.
  • Presentation: Wear Glucose 10% (SG10%).
  • Practical calculation: 2.5 mL/kg of SG10%, to pass in 2-5 minutes. Avoid more concentrated solutions due to the risk of phlebitis.

Maintenance Infusion

  • Start an infusion of SG10%.
  • Glucose Infusion Rate (VIG): Start to 6-8 mg/kg/min to maintain blood glucose > 70 mg/dL.
  • VIG formula: (Dextrose Concentration (%) x Flow (mL/h)) / (6 x Weight (kg))

Glucagon (Alternative if there is no IV access)

  • Indication: Only if there is difficulty obtaining venous access quickly.
  • Dose: 0.5mg (if < 25 kg) or 1.0 mg (if > 25 kg) Intramuscular (IM) or Subcutaneous (SC) route.
  • Important: Its effectiveness is limited if glycogen reserves are depleted, as is often the case in these cases.

Diagnostic Tests

In the Acute Episode

  • Capillary and venous glycemia.
  • Urine test strip: Search for ketones.
  • Venous blood gases: Evaluate metabolic acidosis.
  • Ionogram, kidney and liver function.
  • Sample critique (if possible): Save serum and frozen plasma for later studies.

Subsequent Studies (if there is recurrence or atypia)

Coordinated by the subspecialist, they may include:

  • Analysis of the critical sample (insulin, C peptide, counterregulatory hormones).
  • Studies of organic acids in urine and acylcarnitines in blood.
  • Controlled fasting test in a hospital environment.

When to Refer to the Subspecialist?

Refer to Pediatric Endocrinology if any of the following situations occur:

  • Atypical age: Children under 18 months or over 6 years.
  • Recurrent or severe episodes requiring frequent hospitalization.
  • Hypoglycemia without significant ketosis (suggests hyperinsulinism).
  • Abnormal clinical findings: Hepatomegaly, myopathy, dysmorphic features, developmental delay.
  • Suspected alternative diagnosis (endocrinopathy, inborn error of metabolism).
  • Poor response to initial treatment in emergencies.

Tips for Parents

Family education is key to prevention. Recommend:

  • Avoid prolonged fasts: Offer frequent meals and snacks, especially before bed (e.g. a glass of milk with cookies).
  • "Sick Day Plan": If the child has vomiting, diarrhea or does not want to eat, it is crucial to maintain hydration and carbohydrate intake. Offer sugary liquids (juices, oral rehydration solutions) in small quantities and frequently.
  • Symptom recognition: Teach to identify the signs of hypoglycemia: paleness, sweating, irritability, drowsiness, behavioral changes.
  • Have a quick source of sugar at home: Such as juices or glucose gels to administer at the first symptoms, if the child is conscious.
  • When to seek medical help: Go to the emergency room if the child has symptoms of hypoglycemia, does not tolerate fluids, or is excessively sleepy.