Inborn Errors of Metabolism Flashcards
what kind of genetic defects are inborn errors of metabolism?
-autosomal recessive genetic defect
what goes wrong with inborn errors of metabolism?
- occurs d/t the absence of an enzyme, cofactor, or transport protein which either degrades or converts one substance to another
- this absence results in either a toxic accumulation of the substrate or the deficiency itself can be toxic
clinical presentation of inborn errors of metabolism
- prolonged and unexplained jaundice
- seizures
- GI disturbances (vomiting, poor feeding)
- failure to thrive
- disturbed acid/base status
- hypoglycemia
- reducing substances in the urine
- neurologic deterioration
- cardiac disorders - cardiomyopathy and arrhythmias
- acute liver disease
How to diagnose inborn errors of metabolism?
- CBC/diff
- electrolytes
- arterial blood gas
- ammonia level
- lactate
- urine for reducing substances
- plasma amino acids
- urine organic acids
How are phenylketonuria and maple syrup urine disease categorized?
disorders of amino acid metabolism
what is phenylketonuria?
deficiency of phenylalanine hydroxylase
- function is to convert phenylalanine to tyrosine
- excess phenylalanine is toxic to CNS and there is a tyrosine deficiency
What are the early symptoms of PKU?
- vomiting and poor feeding
- irritability
- musty smelling urine
- eczema
How is PKU diagnosed?
newborn screen
-serum phenylalanine level > 25 mg/dL
How is PKU treated?
- if treatment doesn’t being prior to 3-4 months, infant can have permanent deficits
- limit intake of phenylalanine (Lofenlac)
What is maple syrup urine disease?
- deficiency of the enzyme which breaks down leucine, isoleucine, and valine
- toxic accumulation occurs
What are the symptoms of maple syrup urine disease?
- severe neurologic symptoms
- vomiting
- metabolic acidosis
- urine smells like maple syrup
How is maple syrup urine disease diagnosed?
- increased levels of leucine on urine amino acids
- state screen?
How is maple syrup urine disease treated?
severely restrict amino acids
Prognosis for maple syrup urine disease
- not good
- too late to treat by the time states screen comes back
What are organic acids?
intermediate breakdown products of amino acids
How are propionic acidemia and methylmatonic acidemia categorized?
disorders of organic acid metabolism
symptoms of disorders of organic acid metabolism?
- metabolic acidosis
- feeding difficulties
- CNS deterioration
- hypoglycemia
- hyperammonemia
- hallmark is elevated anion gap
treatment for disorders of organic acid metabolism
protein restriction
prognosis for disorders of organic acid metabolism
-usually not caught soon enough, thus poor prognosis
How is galactosemia categorized?
disorder of carbohydrate metabolism
What is galactosemia?
-lack of enzyme necessary to breakdown galactose; increased levels of galactose are toxic
what is the hallmark symptom of galactosemia?
reducing substances in the urine (galactose)
if not treated, what can eventually happen to kids with galactosemia?
- cataracts (galactose accumulates in the aqueous humor)
- cirrhosis of the liver (galactose accumulates in the liver causing damage)
how is galactosemia diagnosed?
- state screen
- increased serum galactose
- measurement of enzyme activity
