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PKU and Phe in teens and adults

New research shows Phe levels matter at every age

For a long time, people thought that high Phe levels were only dangerous for the brains of babies and children. But now we know that high Phe is also bad for the brains of teens and adults with PKU.

New studies show high Phe lowers intelligence (IQ), even in teens and adults.3 High Phe seems to affect certain kinds of thinking more than others. Studies show that high Phe can cause problems with:

High Phe can affect your thinking

  • Lower intelligence (IQ)
  • Bad moods, being cranky or irritable
  • Feeling "foggy"
  • Thinking and responding slower
  • Depression
  • Feeling anxious
  • Not being able to focus or pay attention3,4,5,6

When it comes to Phe, lower is better*1

The good news for teens and adults is that the problems from high Phe levels can be prevented or improved.

Keeping Phe low can help you prevent:

  • Loss of intelligence (IQ)2

Keeping Phe low can help you improve:

  • Slow reaction time
  • Feeling "foggy"
  • Bad moods, depression, feeling anxious3,4,5,6

How low is low?

There is no clear rule about a safe level for babies, children, teens or adults, although new research shows that high levels can cause many problems.3,4,5

Work with your doctor to set your own target level.

In general, lower is better* to protect your brain and help you be your best.1,2

People who don't have PKU have Phe in the 55-60 μmol/L (1 mg/dL) range.7 So, even the lowest recommended levels for people with PKU are much higher than normal. Lower is better for your brain.*1,2

* Lower is better until you get Phe into the normal range of 1-2 mg/dL. Going lower than 1-2 mg/dL can be unhealthy. Talk with your doctor about the right target range for you.1,2

In people living with PKU, high Phe levels can cause mood problems including depression.6

It may be depression if you have many of the following symptoms:8

  • Overall sad mood, state of worry and/or feeling "empty"
  • Not wanting to do the activities you like, or enjoying them when you do
  • Being hungry all the time, or not at all. Losing weight without meaning to, or gaining a lot of weight very fast.
  • Trouble sleeping or sleeping too much
  • Feeling tired all the time
  • Body movements or actions you are not aware of
  • Feeling worthless or not having hope
  • Inability to focus or make decisions
  • Not wanting to live
    (If you have thoughts about not wanting to live, contact a doctor right away)

High Phe may be causing you to feel this way. If you suspect depression, talk with a doctor or therapist.6

High Phe levels can cause a range of mood problems including social anxiety.6

Here are common symptoms of social anxiety:8

  • Fear of doing something that will be embarrassing
  • Fear that other people are judging you
  • Not doing activities because of anxiety
  • Anxiety and stress when doing something
  • Panic attacks — sudden and strong fear that happens without warning and causes body symptoms like blushing, heart pounding, sweating, stomach ache, and trembling

High Phe may be causing you to feel this way.6,9 If you suspect social anxiety, talk with a doctor or therapist.6

High Phe levels can cause a range of mood problems including "panic disorder."6,9

Panic disorder is when you often have panic attacks, or worry about having panic attacks, or avoid events or places because you're afraid of having a panic attack.

A panic attack is a strong, sudden fear that has body symptoms such as:8

  • Strong or fast heartbeat
  • Sweating
  • Trembling or shaking
  • Hard time breathing
  • Choking
  • Chest pain
  • Upset stomach
  • Being dizzy or faint
  • Feeling "unreal" or detached
  • Fear of losing control or going crazy
  • Tingling or numbness
  • Chills or hot flushes
  • Fear of dying

Symptoms of a panic attack are usually strongest in the first 10 minutes. People who have had a panic attack in one kind of place (like a crowded room, or elevator, or bridge) may come to fear that kind of place and avoid it.8

If you have frequent panic attacks and think you might have panic disorder it may be caused by high Phe. You should talk with a doctor or therapist.6

High Phe can cause a range of mood problems including agoraphobia.9

Studies show people with PKU are more likely to be afraid of going out, for fear of having a panic attack or other problem in public. This is a condition known as agoraphobia.9

It may be agoraphobia if you:8

  • Worry about being in places where you would be unable to get away or get help if you were to have a panic attack or other problem
  • Avoid doing activities you would like to do because of this worry

If you are having symptoms of agoraphobia, it may be caused by high Phe. You should talk with a doctor or therapist.9

  • Symptoms of Depression
  • Social Anxiety Symptoms
  • Symptoms of a Panic Disorder
  • Agoraphobia Symptoms

Next: History of PKU