Took 5000mcg sublingual before blood test

My serum levels have never been above 600, usually hover around 400 after Dx with deficiency in 1995. I've been noncompliant with shots for a year but have been taking sublingual methylcobalamin 5000mcg. I took one the morning of my test and serum measured 1968!! High levels can be a marker for cancer, but was my test skewed? I plan to repeat, but how soon? I haven't taken sublingual in at least a week.

5 Replies

  • PS - I tested negative for PA so my deficiency is "idiopathic"

  • Whenever I have a test I come off of any supplements for 6 weeks. I take 3,000iu if vitd daily and recently had a test so stopped taking my drops 6 weeks before. I was also advised by my doctor to stop iron tablets (due to low ferritin levels) at least four weeks before any tests.

    Hope this helps.

    Moggie x

  • Thanks, Moggie. That makes total sense. I would hope that B12 would flush a little sooner because it is water-soluble and our kidneys are supposed to get rid of excess. I'll have it tested again in a bit after I give the sublingual tabs a rest.

  • B12 may be water soluble, meaning large amounts in the blood will get flushed out via the kidneys. But it is also stored in the liver. The liver will secrete bile containing B12 into the small intestine where, in somebody with normal absorption, it will be reabsorbed back into the body (enterohepatic recycling). That means it can take many, many months for the levels of B12 to drop.

    Those of us with PA don't produce Intrinsic Factor, which is required to reabsorb the B12. So the stuff in our bile gets eliminated in the faeces.

  • Your welcome and I would say you probably skewed your test by taking B12 that morning. Hope your retest, after a few weeks off of the B12, comes back at a better level.

    Moggie x

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