My cobalt is rising; but my chromium is normal. However I have not heard of the effect multivitamins can have on blood results; I will check into it. I do not currently take a multivitamin; I do, however, take vitamin D daily.

I'm sure that in some cases, the minerals in supplements can "move the needle" a little on the levels of certain metals in blood serum.
This discussion is about a slightly different topic - over a period of years metal-on-metal joint implants were used in hips instead of metal-on-ceramic, metal-on-polymer or ceramic-on-polymer. The theory was that the metal joints would be longer lasting and thus a better choice for younger and more active people. It was assumed that the synovial fluid would lubricate and prevent excessive wear.

Unfortunately, over time it was determined not to work for many people (at least half of those with the implants.) Chromium and Cobalt serum levels in the blood and in the tissue surrounding the implants became dangerously high, there were joint failures, tissue death and serious health consequences. The solution was to remove the offending implants, clean up the tissue damage, and replace with safer materials. Over time, once the metal was no longer being shed, the person's chromium and cobalt levels returned to normal - sometimes leaving behind permanent health problems.

We are talking here about metal levels, especially Cobalt, rising from fractions of ppm to the teens, or even high double digits. At that point, the heart, lungs, brain and thyroid can all sustain damage.

Have you had joint replacement surgery?