Vitamin D levels and XP

Xeroderma pigmentosum (XP)

If you have XP, your body cannot repair skin damage caused by ultraviolet radiation (UVR) from sunlight.

A small amount of vitamin D comes from food, but most is made in the skin through exposure to sunlight.  

Most people with XP need to take vitamin D supplements to stop them from having low vitamin D levels. This is because they need to protect their skin from sunlight. 

When you come to the XP clinic, you have a blood test to check your vitamin D level. If it's low, we ask your GP to prescribe a vitamin D supplement. This might also include some calcium. 

Having a low vitamin D level

Vitamin D takes in and uses calcium to keep your bones and teeth healthy. It also helps the body to fight infections and to keep your muscles working well. 

Most people with low levels of vitamin D do not feel any different. However, some people with very low levels have bone pain (often in the legs) and muscle pain or weakness. 

Vitamin D supplements

There are small amounts of vitamin D in oily fish, eggs and meat. However, it is difficult to have normal levels of vitamin D through diet alone. 

The best way to take regular vitamin D supplements is by mouth. They are available in a liquid or spray, or as tablets.

Most people with XP need to take vitamin D supplements in the long term. Your GP can give you a repeat prescription.

  • Tell the doctor who prescribes your vitamin D supplements about any other medicines you take.
  • When you start taking a new medicine, check with your doctor if it might not mix with your vitamin D supplements.
  • Do not stop taking the vitamin D supplements, unless a healthcare professional advises this.

Side effects of vitamin D supplements

It is very rare to get side effects from vitamin D. However, people can react in different ways to medicines.

If you feel sick (nausea), are being sick (vomiting) or have diarrhoea, contact your GP. They can check that the vitamin D level in your blood is not too high. 

Testing your vitamin D level

When you take vitamin D supplements, it's important to check your vitamin D level with regular blood tests. 

  • The first blood test is after 3 months of starting the supplements. 
  • If these results are normal, you will have a test each year after that. 

We can check your vitamin D level when you come to the XP clinic. You can also have this blood test at your GP surgery or local hospital. 

Please tell your XP clinical nurse specialist if you have your vitamin D level measured locally. They can then keep our records up to date.

Resource number: 3512/VER4
Last reviewed: December 2021
Next review due: December 2024

Contact us

If you have any questions or concerns about XP, please contact the XP clinical nurse specialist (CNS).

Phone: 020 7188 6339 or 020 7188 6351, Monday to Friday, 8am to 4pm

Out of hours, please leave a message on the answer phone with your contact details. Someone will return your call in 24 hours.

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