A 6-year-old previously healthy boy is brought to the emergency department after losing consciousness. His parents report that he had poor oral intake for the past 2 days due to a viral illness, followed by dizziness and jitteriness before the episode.
In the emergency department, his blood glucose is 37 mg/dL.
Laboratory evaluation shows:
- High serum and urine ketones
- Undetectable insulin level
- Elevated cortisol and growth hormone levels
What is the most likely diagnosis?
A. Insulinoma
B. Adrenal insufficiency
C. Ketotic hypoglycemia
D. Fatty acid oxidation disorder
Correct Answer: C
Explanation:
Ketotic hypoglycemia is the most common cause of hypoglycemia in otherwise healthy young children, typically occurring between ages 18 months and 7 years.
It usually occurs after prolonged fasting or illness with poor oral intake.
Typical findings include:
- Hypoglycemia after fasting
- High serum and urine ketones (due to increased fat metabolism)
- Low insulin levels
- Elevated counterregulatory hormones such as cortisol and growth hormone
Other options:
- Insulinoma → high insulin with suppressed ketones.
- Adrenal insufficiency → low cortisol levels.
- Fatty acid oxidation disorders → hypoketotic hypoglycemia (low ketones)
Board Pearl:
Low glucose + high ketones + normal counter-regulatory hormones → ketotic hypoglycemia.