Urea Cycle Defects Flashcards Preview

Inborn Errors Of Metabolism > Urea Cycle Defects > Flashcards

Flashcards in Urea Cycle Defects Deck (4)
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UCD Pathophysiology

Can't convert excess nitrogen into urea >>
Excess ammonia, glutamine, gylcine

all AR except OTC Deficiency (x-linked, affects girls to varying degrees)

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UCD Symptoms

Mild: sx during metabolic stress or chronic developmental delay
Moderate: FTT, developmental delay
Severe: poor feeding, lethargy, emesis, HYPERPNEA, hypotonia
hyperpnea can >> respiratory alkalosis
*Arginase deficiency >> SPASTIC DIPLEGIA

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UCD Diagnosis

Urine OA/Serum AA Patterns
CPS1 Defiency:
high ammonia, glutamine, glycine (plasma)
low citrulline (plasma)
normal orotic acid (urine)
OTC Deficiency:
high ammonia, glutamine, glycine (plasma)
high OROTIC ACID (urine)
low citrulline (plasma)
Citrullinemia: argininosuccinate synthetase deficiency
high citrulline (plasma and urine)
low argininosuccinate (plasma)
high ammonia, glutamine, ALANINE (plasma)
slightly high orotic acid (urine)
Arginase Deficiency: hyperammonemia

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UCD Treatment

Alternative methods of nitrogen excretion:
NaBenzoate, Phenylbutyrate
Protein restriction
HD for severe hyperammonemia during crisis