This topic is about someone who has had an ileostomy for 33 years and is experiencing severe vitamin D deficiency, which is causing problems with their feet, bones, muscles, and skin. They are curious if their long-term use of cortisone or the ileostomy itself might be contributing to this deficiency. Here are some helpful insights and advice:

1. Cortisone and other corticosteroids:
- Long-term use of cortisone and similar steroids can reduce vitamin D levels and interfere with calcium absorption, potentially leading to bone loss and issues with muscles and skin.
- Chronic use of steroids can also lower levels of vitamins B12, B6, folic acid, and potassium, which might worsen muscle and skin problems.

2. Other drugs that might affect vitamin D metabolism or absorption:
- Cholesterol-binding resins such as Cholybar, Colestid, and Questran.
- Certain epilepsy medications and barbiturates.
- Hormone-replacement therapies, some laxatives, and the sleeping tablet Doriden.

3. Testing and information resources:
- A recommended website for more detailed information is the "Vitamin D Learning Centre" at http://www.allergymatters.co.uk/acatalog/Vitamin_D_Learning_Centre.html.

4. Reversing deficiency and protecting bones:
- Consider taking supplements that combine calcium and vitamin D, like Caltrate.
- Increase safe exposure to sunlight to naturally boost vitamin D levels.
- If possible, address the underlying need for steroids; some have noted improved health and increased vitamin D levels after stopping corticosteroids following an ileostomy.