Board Questions

1. 2 day old ex FT infant, repeat C-sxn, poor feeding, looks more tired to mom.     Labs: Electrolytes normal, BG 77, BUN <3, Cr 0.2, pH 7.5, PCO2 29. Most likely diagnosis:


a)      Sepsis

b)      Mitochondrial disease

c)       Urea cycle defect

d)      Medium-chain acyl-CoA dehydrogenase deficiency (MCADD)

e)      Methylmalonic Acidemia


2. 4 day old ex FT boy, born NSVD,  poor feeding, lethargy.  Initial labs: Na 140, K 4, Cl 96. Bicarb 14 BUN 26, Cr 0.3, BG 67. Ammonia 470. Lactate 2. Most likely diagnosis

a)      Sepsis

b)      Mitochondrial disease

c)       Urea cycle defect

d)      Medium-chain acyl-CoA dehydrogenase deficiency (MCADD)

e)      Methylmalonic Acidemia


3. 5 day old ex FT girl, progressive lethargy, tachypnea, poor feeding. Seizure upon arrival to ED.  Na 135, K 4, Cl 99, bicarb 22, anion gap 18  BUN & Cr normal. Blood glucose <20, U-ketones negative. Ammonia 600. Lactate 6.4 Most likely diagnosis?

a)      Sepsis

b)      Mitochondrial disease

c)       Urea cycle defect

d)      Medium-chain acyl-CoA dehydrogenase deficiency (MCADD)

e)      Methylmalonic Acidemia




ANSWERS & EXPLANATIONS

1. C. The patient has a respiratory alkalosis in addition to a normal blood glucose and very low BUN, making an urea cycle defect the most likely IEM present.

2. E. The patient has an elevated ammonia level with an anion gap of 30 and a normal blood lactate and glucose level, making an organic acidemia the most likely cause. Hence, Methylmalonic acidemia is the best choice/

3. D. The patient has profound hypoglycemia in the context of negative urine ketones and lactic acidosis, suggesting a defect in fatty acid oxidation. These patients can also have significant liver dsyfunction, producing 
         hyperammonemia. Hence, MCADD is the best choice.

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