IEM & general information of healthy infants Flashcards
def. inborn error and IEM
Definition: inborn error
o Gene mutations, usually caused by recessive gene
o Dysregulation in the synthesize of enzymes, coenzymes and transporters necessary for the metabolism of carb, lipids and amino acids
Definition: metabolism
o Accumulation of toxic metabolites
o Deficiency in essential metabolites
T/F IBE can be detected at early age
F
IEM may start to present at any age with wide range of severity but mostly manifest around the newborn period
why do newborn error screening?
there was high incidence of metal retardation before screening; to catch the problem before the damage becomes accumulated
list down 5/8 common syntoms
- overwhelming illness in the new born period
- cardiomyopathy
- seizure
- recurrent vomiting
- developmental delay/mental retardation
- neuropsychiatric symptoms
- poor growth/failure to thrive
- loss of previously acquired skills
newborn error screening: test
First test: urinary phenyl pyruvic acid for PKU
Dry blood spots: collect 24-48 hours after birth for metabolic intermediaries detection
• Canada: 38 conditions
6 guidelines for IE
- In differential diagnosis of sepsis, anoxic encephalopathy or toxic ingestion
- Persist symptoms
- Typical common laboratory test fail to determine a definitive diagnosis
- Can present as either acute illness or as chronic disease/ recurrent and progressive/ at any age
- Can occur in the context of negative family Hx or genetic/metabolic disorder (recessive gene mutation)
- Neonatal death from undetermined causes
list down the first 3 most common IEM conditions
PKU: phenyl ketonuria
MMA: Methylmalonic acidemia
galactosemia
what is the different between Mitochondrial disorder and other common IEMs?
it is from X chromosome only: x-linked mtDNA mutations.
Most IEMs are autosomally recessive
Most commonly absent enzyme: PKU
PAH: phenylalanine hydroxylase
Most commonly absent enzyme: MMA
Methyl malonyl
4 Modals for nutrition management
A: restrict substrate
B:supplement product
C:supplement co-factor to increase residual enzyme activity
D: ajunct therapies—remove abnormal metabolites
what are the 4 difficulties in terms of nutrition management?
- single or multiple nutrition restriction
- risk of nutrition deficiency
- specific supplements, especially regarding essential AAs
- Appropriate growth = the achievement of metabolic balance, which is hard
what is the priority in nutrition management? how to monitor?
- NRG adequacy
- proteie-energy ratio
if someone has IE of protein metabolism, how would you increase total NRG?
choose low-protein breads and pasta for NRG adequacy without adding more protein to the foods
AAs mix vs the source of whole protein
prefer to whole protein (more efficient in some disorder)
why protein balance is very important?
- Growth will be limited by the AA in shortest or inadequate nitrogen supply in the diet.
dietary fat is a good source to meet NRG requirement except:
IE regarding fat oxidation
Four 4 steps in terms of overall PKU management
- Reduce blood phe under 360 umol/L
- Add little by little intact protein to cover phe needs
- Supplement with large neutral AA to compete for he transporter
- Inadequate protein = Assess deficiency?
How to reduce blood phe under 360 umol/L
Fully restrict all protein sources that contain Phe until below 360 umol/L
Acute management of PKU for infants
- Reduce blood phe < 360 umol/L
- Phe-free formulas
- Can reintroduce standard formula or breastmilk in controlled amounts (the level of phe vary)
chronic management of PKU for infants
- Manintain blood phe at range 120-360 umol/L
- Supporting normal growth and development
- Preventing nutrient deficiencies
what is the main end goal of nutrition therapy for IEM
nutrition adequacy for growth (follow the growth curve)
what is Galactosemia
: high accumulation of galactose-1-P, galactose, galactitol and galactonate due to deficiency of GALT. Sometimes, other enzyme deficiencies may exist as well, like GALK and GALE.
the most common complication
jaundice because of liver damage
