Thanks enbloc
Another thing to keep in mind to tell the neurologist when I go for PN testing. I have autoimmune Addison's disease (which is why I can't stop the steroids), but I suspect the PN symptoms may be due to B12 deficiency - which is known to be a possible secondary condition to AD. I'm about halfway through reading Mrs D's sticky on B12 and you're right the info on steroids & B12 tests is probably there somewhere (having trouble remembering what I've already read but will persevere and make some notes).

MrsD,

Can you help out with this question...do steroids effect B-12 testing? If so, in what way?

The b12 test measures
The red pigment that cobalamin
Has in the sample.
I'll have to research this further.
Steroids increase metabolism and may
Use up B12 faster. I am on my phone
Now and searching is complicated.
I'll post tomorrow.

This link provides a long list of the effects of steroids on various nutrients including B12..

http://www.copd-international.com/li...costeroids.htm
Use of corticosteroids in treating Addison's is typically a physiological dose, and not a high one. But it is possible to be given a higher dose if treatment is targeting the autoimmune process as well.

It is unclear to me from the post above...if bluesfan means that B12 becomes low in Addison's disease, or if the use of steroids at the same times as B12 is tested, or if the steroids used to treat Addison's causes low B12?

So far I've only addressed the 3rd possibility.

B12 can become low now in about 40% of patients, most of whom do not have Addison's which is not common. Use of metformin, use of GERD medications, and vegan lifestyle, or a natural decline in stomach acid, or autoimmune attack on the parietal cells of the stomach are causes of poor B12 absorption from food sources.

I believe she feels her PN may be related to B 12 deficiency. However, she takes low dose steroids for Addison's. The question is whether the steroids will effect her B 12 lab test...and if so, how? In other words, do steroids skew the results of B12 testing?

I would not think this would be factor at the testing lab level.

I looked up hydrocortisone which is the typical treatment for addison's, and could not find easily the human testing technique.
But I did find assay information that used thin layer chromatography to assay tablet compositions.

B12 is a colorimetric assay (utilizing a light source)... comparing to the color density of a known concentration and is called spectrophotometry. This is because B12 is a bright red color and this can be used easily and cheaply.

But I am not a lab technician, but only worked in chemistry labs as a student many years ago.

When in doubt, call the lab. I seriously don't think a doctor would have this information. And one can always stop using B12 if they are on high dose already, at least 3 days before any
testing for steroids, just to be sure.
Labs have huge data bases of what to avoid before any test that they can refer to to guide the patient.

Thanks again enbloc & Mrs D for following this up. Very useful info, especially about the effects of steroids on nutrients. Just to clarify - I haven't been taking any B12 any supplements (yet) because I would like to try and identify the cause of the PN if possible. From reading Mrs D (and others) postings on Neurotalk I'm suspecting B12 deficiency might be a part of the puzzle. I'm waiting for a neuro appt. (hopefully in the next 3 mths) and am gathering info to prepare for this.