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Nursing Care Plan for Phenylketonuria (PKU)

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Phenylketonuria (PKU) is an inherited disorder in which the body cannot metabolize phenylalanine (Phe), which is an amino acid found in many foods. When phenylalanine levels get too high, it can cause intellectual disability, brain damage or death. Classic PKU is the most severe form of the disorder and doesn’t usually show symptoms until the infant is a few months old, but can lead to severe brain damage if not treated. Milder forms of the disorder may be controlled with diet.  All babies born in hospitals in the United States receive testing for this disorder when they are born through a heel stick blood test. Early diagnosis and treatment can relieve symptoms and prevent the development of brain damage and intellectual disabilities.


Phenylalanine (Phe) is an amino acid that is the building block of proteins. This substance is found in most foods, especially protein rich foods like milk, meat and pasta. In PKU, there is a genetic mutation that causes a deficiency in the enzyme that is needed to process phenylalanine causing extremely high Phe levels that affect the brain. As an autosomal recessive trait, a person may be a carrier, but not actually have the disease. Both parents must carry the trait in order to have a child with the disease.

Desired Outcome

Patient will have optimal cognitive functioning; patient and family/caregiver will be educated on diet and prevention of symptoms; patient will maintain optimal learning ability; patient will be free from injury

Phenylketonuria (PKU) Nursing Care Plan

Subjective Data:

  • Hyperactivity
  • Behavioral or emotional problems

Objective Data:

  • Fair skin and hair, blue eyes
  • Slow growth
  • Musty odor of the urine, skin or breath
  • Seizures
  • Skin rash (eczema)
  • Microcephaly

Nursing Interventions and Rationales

  • Assess skin for rash


Patients with PKU often have eczema that is difficult to control;


  • Perform heel stick diagnostic test after birth as ordered


Heel sticks are done on newborns to diagnose PKU. This should be done in a timely fashion, as certain infant formulas contain phenylalanine.


  • Monitor serum lab results


PKU is usually diagnosed within a few weeks of life. Make sure parents are aware if their newborn has received a positive test result.

Monitor patient for elevated levels of phenylalanine routinely and if symptoms appear


  • Inform parents/caregivers of appropriate foods and formulas to give


Special formulas will be required that are phenylalanine free. Refer to dietitian for guidance.

Foods to avoid:

High protein foods, such as milk, dairy products, meat, fish, chicken, eggs, beans, and nuts.


  • Provide safety for patient with seizures (seizure precautions)


Patients with high levels of phenylalanine may have convulsions or seizures. Safety is important to prevent injury. Provide cribs and make sure rails are up.


  • Monitor growth and development


Children with PKU often have slow growth and development. Monitor for changes in growth or signs that developmental milestones are not being met.


  • Administer medications as necessary


Sapropterin is an approved medication that has been found to lower phenylalanine levels in combination with special diet.  It is important, however, that families recognize that dietary changes should be adhered to, regardless of medication use.


  • Provide patient and family education regarding diet, safety and disease process


Maintaining low phenylalanine diet will be a lifelong requirement. Make sure patients’ families understand how to read labels, make healthy diet choices and provide support as necessary

Safety should be stressed, especially in situations where patient may have convulsions or seizures



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