Phenylketonuria (PKU) is a rare genetic disorder that affects the body’s ability to break down the amino acid phenylalanine (Phe) found in protein.

When Phe builds up in the blood, it can cause some serious health problems, including intellectual disability and neurological issues. PKU is not curable, but management and early detection are vital for preventing the development of health complications. In this article, we will explore the symptoms, causes, screening, and management of PKU.

Symptoms of PKU

The leading symptom of PKU is a musty odor that is detected in the child’s urine, skin or sweat. Other symptoms include:.

Developmental delays
Intellectual disability
Psychiatric disorders
Hypertension
Behavioral issues
Seizures
Skin rashes
Hypopigmentation (fair skin, hair and eyes)

A phenylalanine-free diet is highly recommended for those whose PKU has been diagnosed.

Causes of PKU

PHE is an amino acid and is found in many foods, including breast milk, formula, and foods that contain protein, like meat, eggs, nuts and/or cheese. PKU is caused by a deficiency of enzymes needed to break down Phe.

The PKU genetic mutation is passed to children from their parents, and it occurs when both the parents have a recessive PKU gene.

When inherited, the mutation leads to the absence or insufficiency of phenylalanine hydroxylase, the enzyme that converts Phe to tyrosine (an amino acid which is required for the synthesis of important neurotransmitters).

Screening for PKU

Early detection of PKU is a critical part of the management plan. In most states, newborns are highly recommended to undergo the PKU screening, and it is usually done within the first 24-48 hours after birth.

The screening involves pricking the baby’s heel for blood samples to test for excess phenylalanine and tyrosine in the blood. If the tests are positive, further testing is recommended for a definite diagnosis.

Management of PKU

PKU can be managed through the dietary elimination of phenylalanine. A lifelong diet therapy is required for individuals with PKU. The goal of therapy is to keep the Phe level in the blood under 6 mg/dL.

This should be consumed without the use of prescription medication. The PKU medication can help lower Phe levels, but with dietary modifications, they may not be as effective.

A well-planned low phenylalanine diet involves the careful avoidance of food items, nutritional supplements that contain Phe such as Aspartame, low protein intake and at times the use of specialized medical formulas prescribed by a dietitian or metabolic physician. For infants, there is infant formula, which is low in Phe, and it should be used to replace breast milk, which otherwise is rich in the amino acid.

Individuals with PKU should be placed under the care of a metabolic physician or a dietitian specializing in metabolic conditions.

They will regularly monitor the individual’s nutritional status, evaluate compliance to therapy and detect any deficiencies due to food restriction. Pregnant women with PKU may benefit from additional supplements to improve their offspring’s health.

Conclusion

Phenylketonuria is a severe metabolic disorder that can cause lifelong disabilities if not detected and managed early. Early detection helps in the management of the disease and prevents the onset of complications.

A well-planned, life-long be carried out through a low phenylalanine diet, and metabolic monitoring by specialists.