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Zorluk: KolayPediatric Genetic and Metabolic Disorders

A 1616-month-old boy is brought to the emergency department by his parents after they were unable to wake him up in the morning. For the past 4848 hours, the child has experienced a mild gastrointestinal illness characterized by vomiting and poor oral intake. Prior to this episode, he has been healthy and his developmental milestones are appropriate for his age. On physical examination, the child is lethargic and hypotonic, but has no rash, jaundice, or hepatosplenomegaly. Vital signs are within normal limits for his age, except for mild tachycardia. A point-of-care blood glucose measurement is 2828 mg/dL. Urinalysis is completely negative for ketones. Which of the following is the most appropriate next step in the management of this patient?

  1. Immediate intravenous dextrose administration and subsequent evaluation for a fatty acid oxidation defectCevap
  2. B
    Empiric administration of broad-spectrum antibiotics for suspected bacterial sepsis
  3. C
    Measurement of arterial blood gas to calculate the expected respiratory compensation
  4. D
    Referral for a comprehensive neurodevelopmental evaluation to assess for delayed milestones
  5. E
    Measurement of serum thyroid-stimulating hormone and free T4 levels

Cevap

Immediate intravenous dextrose administration and subsequent evaluation for a fatty acid oxidation defect
The patient presents with acute, severe hypoglycemia accompanied by an inappropriate absence of urinary ketones after a period of poor oral intake. This classic presentation of 'hypoketotic hypoglycemia' is highly suspicious for a fatty acid oxidation disorder, most commonly medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. During fasting, the body normally breaks down fatty acids into acetyl-CoA, which is then converted into ketones to provide an alternative energy source for the brain. In MCAD deficiency, this process is impaired, leading to severe hypoglycemia without the expected compensatory ketone production. The immediate, life-saving next step is to restore blood glucose levels with intravenous dextrose, followed by a specific metabolic evaluation (such as an acylcarnitine profile) to confirm the diagnosis.

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1
Evaluate the clinical presentation and laboratory findings.
The patient has profound hypoglycemia (2828 mg/dL) and absent urinary ketones after a period of fasting due to a viral illness.
Recognizing the combination of hypoglycemia and lack of ketones (hypoketotic hypoglycemia) is the critical step in differentiating the underlying metabolic mechanism.
2
Identify the likely underlying pathophysiological condition.
The inability to produce ketones during fasting hypoglycemia strongly points to an impairment in fatty acid beta-oxidation, such as medium-chain acyl-CoA dehydrogenase (MCAD) deficiency.
Fatty acid oxidation is physiologically required to generate ketones (an alternative brain fuel) and support gluconeogenesis when glycogen stores are depleted.
3
Determine the most appropriate immediate management.
Intravenous dextrose must be administered immediately to reverse the severe hypoglycemia, followed by specific metabolic diagnostic testing.
Hypoglycemia is a life-threatening emergency that must be corrected instantly to prevent permanent neurological injury, taking precedence over definitive diagnostic tests.

Anahtar Kavram

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency and the management of hypoketotic hypoglycemia.
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Konular

Pediatric Genetic and Metabolic Disorders

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