ED Board Questions

Tamara Gayle, MDPGY-1

Question 1A 4 year old girl who has the classic form of Maple Syrup Urine Disease is brought to the emergency department. She recently started pre-K and has had a temperature of 39.5 since this morning with continuous episodes of vomiting. In the ED she appears very lethargic and is now very difficult to arouse on exam. She also has crackles heard in the right lower base.

Of the following the best NEXT step in management is:

A. Check electrolytes B. Obtain blood cultureC. CXRD. CTE. Start hydration

A. Check electrolytes B. Obtain blood cultureC. CXRD. CTE. Start hydration

What is Maple Syrup Urine Disease?Autosomal recessiveDue to defect in the Branched Chain Ketoacid

Dehydrogenase (BCKD) enzyme, which catalyzes the breakdown of branched chain ketoacids

These ketoacids form from breakdown of branched chain amino acids: leucine, isoleucine, and valine

These amino acids accumulate in the bloodAccumulation of leucine and isoleucine cause

characteristic smell in the urine

Back to the question.. A metabolic crisis is typically caused by a

stressor such as illness, trauma, etc. Management includes:

Stop all protein intake Provide hydration with high caloric

supplementation Correct metabolic abnormalities Eliminate toxic metabolites Treat precipitating factor (s) Provide cofactor supplementation Prevent associated sequale

Cerebral edema “Leucine encephalopathy”Increased concentrations of leucine are

toxic Consider if neurologic signs such as

vomiting, clonus, lethargy, etc developIf suspected obtain a CT or MRIIf confirmed, infuse mannitol at 1-2

grams/kg over 30-40 minutesAdd IV lasix for diuresis by carefully

monitor serum sodium Most common cause of death in MSUD

Question 2You are evaluating a 7mo old male who has Maple Syrup Urine Disease in the emergency department. He has not been feeding well for the past two days, because his parents feel he is coming down with a flu-like illness and is now going into metabolic crisis. Which of the following electrolyte abnormalities are you MOST likely to find:

A. Metabolic alkalosis and hypernatremiaB. Metabolic acidosis and hyponatremia

C. Metabolic alkalosis and hyponatremiaD. Metabolic acidosis and hypernatremia E. Respiratory alkalosis and hyponatremia

A. Metabolic alkalosis and hypernatremiaB. Metabolic acidosis and hyponatremia

C. Metabolic alkalosis and hyponatremiaD. Metabolic acidosis and hypernatremia E. Respiratory alkalosis and hyponatremia

Pathophysiology breakdown Catabolic stress->endogenous protein breakdownIncrease in the branched chain amino acids (leucine,

isoleucine, and valine)Also occurs with an excessive amount of protein

ingestionIncreased ketoacids and glucose utilization

ketosis

metabolic acidosis

Metabolic acidosis 101 Slowly correct with rehydration and high

caloric intakeIf serum bicarb is below 14 meq/L and blood

pH <7.2, give IV bolus NaHC03 as 2.5 meq/kg over 30 minutes, then 2.5 meq/kg/day until serum bicarb is 24-28 meq/L

Goals:Serum bicarb level over 24 mew/LAsence of ketones in urine

Sodium management Maintain serum sodium at 140-145 meq/LMonitor urine sodium loss an replacement

requirement As sodium apporaches 140-145meq/L,

reduce IV fluids to D10 1/2NS and monitor sodium closely

After 24 hours adjust sodium intake to provide 4meq/kg/day

References New England Consortium of Metabolic Programs

Current Diagnosis and Treatment. Pediatrics. Sondheimer et. al. Lange.

Up to date

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