What Factors Affect Phe Levels

Having PKU should not prevent you from gaining or maintaining excellent general health. As with the rest of the adult population, eating a healthy varied diet, enjoying good quality sleep and staying physically active, all have a part to play in this. However, if you have PKU, an additional consideration is keeping your Phenylalanine (phe) levels within the levels recommended for you.

Knowing what can affect your phe levels can help you understand how to cope with levels if they increase. Some of the factors that might affect your phe levels include:

• Being unwell
• Physical activity and undereating
• Rapid weight loss
• Hormonal changes e.g. the menstrual cycle and early stages of pregnancy
• Eating more or less phe exchanges than advised and not taking your protein substitute as prescribed.

Your metabolic team will be able to give you more guidance on these, so you will know what to expect.

It is important that you contact your metabolic team or GP if you are unwell and struggling to eat and drink enough.

If you must take medication when unwell, remember, some medications contain aspartame, which is a source of phe, and these must be avoided (unless your doctor or metabolic team tells you otherwise). Always check the ingredients of medications with your metabolic team or pharmacist before taking.

Here are some suggestions on how to minimise the rise in your phe levels during illness:

• Try and eat small frequent meals as tolerated to ensure adequate energy (calorie) intake.
• Aim to take your protein substitute as normal. If you’re unable to do so, make sure you contact your metabolic team straight away.
• Consider your phe exchanges. Your metabolic team may advise you to cut back on phe exchanges if phe levels are raised. You might find that this will have happened naturally as appetite may be reduced during illness.
• Stay hydrated. Ensure adequate fluids are taken especially if your symptoms include vomiting and/or diarrhoea.
• Check for suitable medication. Look out for aspartame and seek the guidance of your pharmacist or metabolic team if you’re unsure. It is also important not to mix any medications through the protein substitute as this will alter the taste and consistency.

A sedentary lifestyle is linked to obesity, heart disease and type 2 diabetes. Your current job may require you to sit for many hours a day. There is nothing stopping you from being active or competing in a sport of your choice. A sedentary lifestyle can be harmful to your health, so physical activity is encouraged wherever possible and through all life stages. One of the many benefits of regular exercise (or manual labour) is that your body will use protein to build muscle. Phe, as an amino acid, is a building block of protein so, the phe from your diet will be used to help build muscle.

For more information on PKU and exercise see Physical Activity and Exercise.

Also, not taking your protein substitute will increase your blood phe further as your overall diet will lack protein and your body will again start breaking down your muscle stores releasing further phe into your blood. For more information on balancing your diet, see How Much Should I Eat?