13 Questions
Which enzyme is likely to be defective in a patient with PKU?
Phenylalanine hydroxylase
What is the probable reason for the increase in serum phenylalanine in PKU?
Deficiency in phenylalanine hydroxylase
What substance is likely to be found in the urine of a patient with PKU?
Phenylketones
What is the normal reference range for serum phenylalanine concentration?
0.05 to 0.1 mmol/L
Which of the following enzymes is involved in the conversion of phenylalanine to tyrosine?
Phenylalanine hydroxylase
What is the likely consequence of a deficiency in phenylalanine hydroxylase?
Elevated serum phenylalanine levels
What is the main consequence of elevated phenylalanine levels in individuals with PKU?
Intellectual disabilities and seizures
Why is early detection of PKU crucial?
To reduce the risk of cognitive impairment and neurological complications
What is the primary treatment for patients with PKU?
Phenylalanine-restricted diet
Why might individuals with PKU need a dietary source of tyrosine?
To support various physiological functions and synthesizing important molecules in the body
What will be found in the urine of individuals with PKU due to the shunting of phenylalanine into alternative metabolic pathways?
Elevated phenylpyruvate levels
What is the consequence of not treating PKU promptly?
- Intellectual disabilities, seizures, and developmental delays*
Why is regular monitoring of blood phenylalanine levels essential for individuals with PKU?
- To adjust the diet and treatment plan accordingly*
Study Notes
Phenylketonuria (PKU)
- The defective enzyme in PKU patients is phenylalanine hydroxylase.
- Elevated serum phenylalanine in PKU is likely due to the impairment of phenylalanine hydroxylase, leading to excessive accumulation of phenylalanine.
Urinary Findings in PKU
- Patients with PKU often exhibit high levels of phenylpyruvate, phenyllactate, and phenylacetate in their urine.
Biochemistry of PKU
- The normal reference range for serum phenylalanine concentration is 30-70 μmol/L.
- Phenylalanine hydroxylase is the enzyme responsible for converting phenylalanine to tyrosine.
Consequences of PKU
- A deficiency in phenylalanine hydroxylase leads to the accumulation of phenylalanine in the blood, causing intellectual disability and other neurological disorders if left untreated.
- Elevated phenylalanine levels in individuals with PKU can cause intellectual disability, seizures, and behavioral problems.
- Early detection of PKU is crucial to prevent severe neurological damage and intellectual disability.
Treatment and Management of PKU
- The primary treatment for PKU involves a lifelong restriction of phenylalanine intake through a special diet.
- Individuals with PKU may require a dietary source of tyrosine, an essential amino acid, since they are unable to convert phenylalanine to tyrosine.
- Regular monitoring of blood phenylalanine levels is essential to ensure that levels remain within a safe range and to prevent intellectual disability.
Complications of Untreated PKU
- If left untreated, PKU can lead to severe intellectual disability, seizures, and behavioral problems.
- Elevated phenylalanine levels can also cause skin problems, such as eczema and skin rashes.
Test your knowledge of phenylketonuria (PKU) with this case study about a two-week-old baby girl who tested positive for phenylketones. Explore the symptoms, diagnosis, and treatment of PKU in this quiz.
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