5 Questions
Which enzyme deficiency leads to failure to synthesize urea and hyperammonemia during the first week after birth?
Ornithine transcarbamylase
What is the toxic substance especially to the central nervous system in the context of urea cycle deficiency?
Ammonia
What combination of symptoms suggests a defect in the urea cycle?
Hyperammonemia, elevated blood glutamine, decreased blood urea nitrogen (BUN)
What symptoms typically appear during the 24 to 72-hour postnatal period if there is a defect in the urea cycle?
Lethargy, vomiting, hyperventilation
What mechanism of ammonia intoxication leads to brain edema?
High level of glutamine within a cell absorbing water
Study Notes
Urea Cycle Deficiency
- Ornithine transcarbamylase (OTC) deficiency leads to failure to synthesize urea and hyperammonemia during the first week after birth.
Toxic Substance
- Ammonia is especially toxic to the central nervous system in the context of urea cycle deficiency.
Symptoms of Urea Cycle Defect
- A combination of symptoms suggesting a defect in the urea cycle includes lethargy, vomiting, hypotonia, and seizures.
Symptoms in Newborns
- Symptoms typically appear during the 24 to 72-hour postnatal period if there is a defect in the urea cycle, including lethargy, vomiting, and seizures.
Ammonia Intoxication
- The mechanism of ammonia intoxication leading to brain edema is due to the production of glutamine in the brain.
Test your knowledge about urea cycle enzyme deficiencies and their impact on urea synthesis and ammonia levels in the body, especially in infants.
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