If you get injections BEFORE you know what level your B12 is at now...you will never be sure about it.

However, B12 itself is very benign, and not harmful to self administer. You do not need injections either, as there are many medical studies out now that demonstrate oral is as effective as
injections.

If you do supplement before testing, you should stop the supplement (oral) at least 5 days before the test to rule out artificially high results. Injections should be stopped at least a week or two before any test.

What IS important is that you need to understand that all people are NOT equal when it comes to activating synthetic cyano B12 ... genetic mutations in the methylation process are very common and synthetic will not work in those people.

Another test is called MMA and it measures whether B12 is being utilized in the tissues properly.

You really need to read the B12 thread here, as the links to all the NEW medical studies are on there, as well as other factors involved with B12 therapy.

The nutritional experts in the US are recommending that persons over 50 take a supplement of B12 ...
http://www.nutrition.gov/dietary-sup...al-supplements

This is the B12 informational thread on this forum:
http://neurotalk.psychcentral.com/thread85103.html

There is a link on that thread to a table of absorption data from a medical study showing Pernicious Anemia (low intrinsic factor) patients absorb about the same amount from oral B12 as normals. However you do have to TAKE oral properly....
it must be taken on an empty stomach for proper absorption in the intestine. You can forget about sublingual... sublinguals dissolve in saliva which is swallowed, and then becomes oral anyway.

http://www.ncbi.nlm.nih.gov/pmc/arti...able/T1/#TF1-4
(The far right column is data from patients with no intrinsic factor.)