Phenylketonuria (PKU)
Phenylketonuria (PKU)
(fen'-il-kee'-to-nu'-ria)
By:Ashley Ryan
What is PKU?
* An inherited metabolic disease in which mental retardation can be prevented by a specific diet
* 1 out of 50 people are carriers of defective gene; 1 in 10,000 births
* Rare condition where a baby is born lacking the ability to break down phenylalanine.
* Phenylalanine is an amino acid found in many foods. It is characterized by higher than normal levels of phenylalanine in the blood which can cause damage to the brain and mental retardation
* The brain suffers and is damaged due to a tremendous buildup of phenylalanine
*This then results in damage of the CNS & causes brain damage
Causes & Symptoms
* Since PKU is inherited it is passed down through families
* Which means both parents must pass on the defective gene to there offspring; known as an autosomal recessive trait
* Phenylalanine is involved in the body’s production of melanin which is the pigment for skin and hair color – children with PKU generally have lighter skin, hair and eyes
* Other symptoms include
Treatment
* PKU is in fact treatable with the correct strictly followed diet very low in phenylalanine
* If diet is not followed brain impairment can occur or error of metabolism can be associated with M.R in first year of life.
* Association with attention-deficit hyperactivity disorder (ADHD) most common problem in those who don’t follow a strict diet
* If diet is properly followed esp. in first few years of life where it is most crucial an outcome of better physical and mental health will follow
* Examples of foods low in phenylalanine: milk, eggs, fish oil, special formula called Lofenalac .
* Lofenalac provides essential amino acids and can be used throughout life. It not only provides amino acids but also vitamins and minerals.
* Can think of it as a super food for PKU patients
Testing for PKU
* It is IMPERTATIVE that phenylalanine restrictions on diet is introduced after birth to prevent the neurodevelopment effects of PKU
* How is PKU tested?
* Blood is routinely drawn from the infants for testing
* A “heel stick” is done and then collected on special blotter paper
* Routine testing includes phenylketonuria and blood type
Prevention
* Overall highly recommend to have strong relationship with physician
* An Enzyme Assay can determine if parents carry defective gene
* Chorionic villus Sampling - screen unborn baby for possibility of PKU
* It is very important that women with PKU closely follow a strict low-phenylalanine diet both before becoming pregnant and throughout the pregnancy, since build-up of this substance will damage the developing baby even if the child has not inherited the defective gene.
Age and Diet- controversy
* The age when a diet can or should be discontinued has been debatable over decades
* Generally- PKU centers advise a life-long diet especially for female patients
* A study was done that looked at progress of children who ended their diet at an early age
* the main focus of the study was the effects on neurological/ intellectual performance
* The participants abilities were compared during treatment and after the diet was discontinued
* RESULTS- It was shown that children who maintained the diet had fewer deficits to those terminating the diet before the age of 10
* Overall the study said a diet should remain strict to at least the age of 10!
* Although this was said also recommended to maintain diet in adulthood
* can be modified but not completely eliminated
Issues in Adults with PKU
* Several studies said that discontinuation of diet effect
* New problems with PKU:
* Adults w/ PKU who remained on diet but weren't as strict w what they ate showed white matter abnormalities when given MRI indicating a reduction in myelin.
* *** These conditions disappeared after reintroducing the strict diet ***
* Neurological investigations in early treated adults w/ PKU who stopped the diet showed higher incidence of neurological signs including:
-tremors
-clumsy motor coordination
* Investigation on Psychological problems also
-severe behavior/ psychiatric problems are seen in profound retarded/untreated adults w/ PKU in their 30’s-40’s.
* Claims that reintroduction of restricted diet symptoms can sometimes be reversible
* Adults who discontinued the diet have had cases of
* - depression, anxiety, social withdrawal, phobias, low self-esteem, neurotic behavior
* In 2009 it was stated PKU patients should be encouraged to remain on a life long diet and also recommended to:
-take nutritional supplements
* Blood PhE levels should be monitored every 3 months
* Yearly clinical review
* PKU pregnant women recommendations include:
* Being under control of physician specialized in
* metabolic disease, gynecologist, and dietician
* Detailed ultrasound @ 20 weeks of gestation
* Seen every 3 to 4 weeks and blood PhE levels monitored at least 1 a week
Factors to consider when people discontinue restricted diets
* Difficulty maintaining diet for older children
* State support of formula costs is decreasing
* In 1978 85% of PKU programs received financial backing, within 6 years 66% of people received financial support
* Formula Cost can range from $5,000 to $7,000 a year. For a young adult and families can be a problem financially if not receiving any support
* Therefore, when people do stop the restricted diet its important to consider and assess financial, nutritional, social, psychological problems that people encounter trying to maintain the diet. And remember that in some cases people don’t discontinue the diet because they want to they may be unable to.
Reference Page
Phenylketonuria (PKU)
Causes & Symptoms
* Since PKU is inherited it is passed down through families
* Which means both parents must pass on the defective gene to there offspring; known as an autosomal recessive trait
* Phenylalanine is involved in the body’s production of melanin which is the pigment for skin and hair color – children with PKU generally have lighter skin, hair and eyes
* Other symptoms include
Treatment
* PKU is in fact treatable with the correct strictly followed diet very low in phenylalanine
* If diet is not followed brain impairment can occur or error of metabolism can be associated with M.R in first year of life.
* Association with attention-deficit hyperactivity disorder (ADHD) most common problem in those who don’t follow a strict diet
* If diet is properly followed esp. in first few years of life where it is most crucial an outcome of better physical and mental health will follow
* Examples of foods low in phenylalanine: milk, eggs, fish oil, special formula called Lofenalac .
* Lofenalac provides essential amino acids and can be used throughout life. It not only provides amino acids but also vitamins and minerals.
* Can think of it as a super food for PKU patients
Testing for PKU
* It is IMPERTATIVE that phenylalanine restrictions on diet is introduced after birth to prevent the neurodevelopment effects of PKU
* How is PKU tested?
* Blood is routinely drawn from the infants for testing
* A “heel stick” is done and then collected on special blotter paper
* Routine testing includes phenylketonuria and blood type
Prevention
* Overall highly recommend to have strong relationship with physician
* An Enzyme Assay can determine if parents carry defective gene
* Chorionic villus Sampling - screen unborn baby for possibility of PKU
* It is very important that women with PKU closely follow a strict low-phenylalanine diet both before becoming pregnant and throughout the pregnancy, since build-up of this substance will damage the developing baby even if the child has not inherited the defective gene.
Age and Diet- controversy
* The age when a diet can or should be discontinued has been debatable over decades
* Generally- PKU centers advise a life-long diet especially for female patients
* A study was done that looked at progress of children who ended their diet at an early age
* the main focus of the study was the effects on neurological/ intellectual performance
* The participants abilities were compared during treatment and after the diet was discontinued
* RESULTS- It was shown that children who maintained the diet had fewer deficits to those terminating the diet before the age of 10
* Overall the study said a diet should remain strict to at least the age of 10!
* Although this was said also recommended to maintain diet in adulthood
* can be modified but not completely eliminated
Issues in Adults with PKU
* Several studies said that discontinuation of diet effect
* New problems with PKU:
* Adults w/ PKU who remained on diet but weren't as strict w what they ate showed white matter abnormalities when given MRI indicating a reduction in myelin.
* *** These conditions disappeared after reintroducing the strict diet ***
* Neurological investigations in early treated adults w/ PKU who stopped the diet showed higher incidence of neurological signs including:
-tremors
-clumsy motor coordination
* Investigation on Psychological problems also
-severe behavior/ psychiatric problems are seen in profound retarded/untreated adults w/ PKU in their 30’s-40’s.
* Claims that reintroduction of restricted diet symptoms can sometimes be reversible
* Adults who discontinued the diet have had cases of
* - depression, anxiety, social withdrawal, phobias, low self-esteem, neurotic behavior
* In 2009 it was stated PKU patients should be encouraged to remain on a life long diet and also recommended to:
-take nutritional supplements
* Blood PhE levels should be monitored every 3 months
* Yearly clinical review
* PKU pregnant women recommendations include:
* Being under control of physician specialized in
* metabolic disease, gynecologist, and dietician
* Detailed ultrasound @ 20 weeks of gestation
* Seen every 3 to 4 weeks and blood PhE levels monitored at least 1 a week
Factors to consider when people discontinue restricted diets
* Difficulty maintaining diet for older children
* State support of formula costs is decreasing
* In 1978 85% of PKU programs received financial backing, within 6 years 66% of people received financial support
* Formula Cost can range from $5,000 to $7,000 a year. For a young adult and families can be a problem financially if not receiving any support
* Therefore, when people do stop the restricted diet its important to consider and assess financial, nutritional, social, psychological problems that people encounter trying to maintain the diet. And remember that in some cases people don’t discontinue the diet because they want to they may be unable to.
Reference Page
Phenylketonuria (PKU)
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