Phenylketonuria

By: Paige Jensen

What is Phenylketonuria?

• “a disorder of protein metabolism with an abnormal increase in the concentration of the amino acid phenylalanine in the blood.”

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• Genetic Metabolic Disorder

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• More common in people of European or Native American descent

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• No signs and symptoms

Pathology

• “a disorder of protein metabolism with an abnormal increase in the concentration of the amino acid phenylalanine in the blood.”

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• Genetic error
• Deficiency of phenylalanine hydroxylase activity
• Deficiency also in Tyrosine

Phenylalanine’s Responsibilities

• Essential Amino Acid
• Exclusively obtained from diet

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• Needed for protein synthesis

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• Also important for synthesis of Tyrosine

Tyrosine’s Responsibilities

• Nonessential Amino Acid
• We obtain from our diet OR our body can synthesize it
• It is synthesized in the body from phenylalanine

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• Important role in the production of neurotransmitters
• Epinephrin, norepinephrine, and dopamine
• Helps produce melanin
• Helps make and regulate hormones
• Adrenal, thyroid, and pituitary glands

How it comes together

The danger

• If not treated:

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• The build up of not broken-down phenylalanine in the bloodstream is shown to be toxic

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• Can cause neurologic damage

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• Resulting in physical altercations, intellectual deficits, and neurodegeneration

Diagnosis

• Blood test

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• Heel prick

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• All newborns (24-72 hours after birth)

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• All newborns in US required
• Although parents can refuse and sign a consent form

Signs and Symptoms

• If tested and diagnosed 1-2 days after birth and start appropriate treatments: no signs and symptoms

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• If not tested and diagnosed and don’t get treatment right away:
• Musty odor breath, skin, or urine
• Neurological issues including seizers possibly
• Skin rashes (eczema)
• Fair skin
• Abnormally small head
• Hyperactivity
• Intellectual disability
• Delayed development
• Behavioral, emotional, and social problems
• Psychiatric disorders

Treatment

• Medical Nutrition Therapy
• Phenylalanine restricted diet
• Medical phenylalanine-free formula
• Special manufactured foods low in phenylalanine

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• Each patient has different restrictions
• Registered Dietitians and genetics teams make the orders

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Details on MNT

• Foods not allowed in restricted meals:
• Cheese and dairy
• Nuts, seeds, dried beans and peas, peanut butter
• Eggs, poultry, meat, fish and other seafood

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• Foods allowed but must be monitored, measured, and/or weighted according to their diet prescription:
• Bread, crackers, potato chips, popcorn
• Fruit, vegetables, and f/v juices
• Special low-protein foods, low-protein cereals

Study 1

• Relaxed diet for PKU patients
• In regard to micronutrient deficiencies

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• Conclusion: PKU patients are at risk for micronutrient deficiencies

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• Although it was a small study and not preformed very long
• Probably not an extremely ethical study

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Study 2

• Effects of unrestricted consumption of F/V for PKU patients

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• There was no impairment of the metabolic control revolving PKU
• This could result in a less strict diet for PKU patients in the future

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• Was only performed for 2 weeks and with 14 children, so it was a pretty small sample size

Study 3

• A study to find the neuropsychological profile of adult PKU patients that are off-diet

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• Shows the outcome of these patients had a lower neuropsycological function than a healthy person

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• Small sample size that contained mostly females

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Insurance Coverage

• Varies from state to state

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• 39 states passed legislation that requires some sort of coverage
• Either for medical food directly from newborn screening or state health department
• Or insurance coverage in general