Urea Cycle Defects Flashcards
1
Q
Clinical Presentation of neonatal onset urea cycle defects
A
Age of onset: >24 hrs of age Lethargy Poor feeding Vomiting Seizures Bleeding Hyperventilation Coma Death
2
Q
Differential diagnosis of lethargic newborn
A
Sepsis
Congenital defect (heart, brain)
Inborn error of metabolism
3
Q
Urea Cycle Defects: treatment
A
RESTRICT SUBSTRATE - essential amino acid formulas PROVIDE PRODUCT - arginine or citrulline REPLACE ENZYME: - liver transplant PROVIDE ALT ROUTES OF ELIMINATION: - ammonia scavengers - i.e. benzoate, phenylacetate TREAT SECONDARY EFFECTS - increased intracranial Pressure, DIC, etc
4
Q
Hyperammonemic encephalopathy
A
damage to brain as result of hyperammonemia usually recur despite therapy Triggers include: - intercurrent infection - fasting - protein loads - surgery
5
Q
Compare the following:
- OTC deficiency
- Arginosuccinate lyase deficiency
- Argininemia
A
OTC deficiency:
- X-linked; more mild in females
Arginosuccinate Lyase:
- typical coarse hair, cirrhotic changes
Argininemia:
- most develop severe lower limb spasticity
6
Q
Later-onset urea cycle defects
A
usually caused by less severe mutations and better residual enzyme activity
Signs and symptoms:
- mental retardation
- recurrent vomiting
- failure to thrive
- Recurrent coma
- History of protein aversion
