Phenylketonuria

Hi guys, in this lecture we are going to look at the diagnosis Phenylketonuria or PKU.

Phenylketonuria is a diagnosis that affects metabolism. It is an autosomal recessive disorder so both parents have to have the trait for the child to have the disease. What’s happening with that the child doesn’t have the enzyme that they need to break down an amino acid called Phenylalanine. When this Phenylalanine builds up in the system you end up with toxicities that can cause long term cognitive and behavioral problems.

If a child has PKU, the first thing you’re going to see digestive problems and they may have trouble meeting growth milestones and gaining weight like expected. But as the phenylalanine builds up in the system you’ll see more toxicity issues like developmental delays and behavioral issues.

For adolescents the behavioral issues tend to look like really erratic, unpredictable and sometimes unsafe behavior

So the most important thing for therapeutic management is early detection. If we can detect this in the first month of life outcomes are actually really good because we can prevent toxicity from happening.

The way that we do this is to screen all newborns with a test called the Guthrie test. This is done by getting blood from a heel stick. The test looks to see how much Phenylalanine is in their blood.

If it is determined that a child does have PKU then the primary treatment is a lifelong restricted diet, avoiding foods that are high in Phenylalanine. These are meat, eggs and dairy products. They also need avoid artificial sweeteners because phenylalanine is found in aspartame.

One issue with this restricted diet is that we can’t eliminate phenylalanine completely because it’s is needed in appropriate amounts for growth and development. So we have to calculate how much they can have based on their age and weight. They will also need supplements to help compensate for some of the nutrients that will be missing from this restricted diet

As is the case with any diet, compliance can become a really big issue and this is particularly true in the adolescent years where it’s really difficult to avoid things like hamburgers and pizza. It’s really important to let parents and kids know that there won’t be any obvious outward sign that toxicity. It’s not like an allergy where you can quickly tell you’ve had too much, it’s just sort of quietly building up toward toxicity.

When you are providing nursing care for a patient who has PKU your priority nursing concepts are going to be Nutrition, Human Development and health promotion. The health promotion part is super important for this patient group because again the primary goal is to detect early on in life so we need to be following up with families and making sure that all newborns are screened.
Okay guys that’s it for a lesson on phenylketonuria. It’s pretty straightforward. So, let’s summarize our key points.

PKU is an autosomal recessive disorder where the child is missing the enzyme needed to break down phenylalanine.

When this happens phenylalanine levels increase and there is a risk for toxicity.

This toxicity negatively affects cognitive development and can cause developmental delays as well as behavioural problems.

To prevent this from happening, early detection is super important so that means screening all newborns with the Guthrie test.

Treatment is all about managing your diet and eliminating those foods that are high phenylalanine.

That’s it for our lesson on Phenylketonuria. Make sure you check out the resources attached to this lesson. Now, go out and be your best self today. Happy Nursing!