I don't believe that carnitine, or lipoic acid will show up on testing.
(unless carnitine levels are ordered, which they are not typically).

B12 will show false elevations, so stopping that for 3 or more days is advised. You should have some stored by now, and not suffer this hiatus.

Magnesium levels have a large middle area of "normal", but I would still take that to see if you are edging into "high" with your supplements. That would be useful to know. So if you want that result, keep taking what you are taking for magnesium.

B-complex will read on blood testing. So stopping that would be a good idea for several days. B6 is stored for several days and not all excreted quickly. The benfotiamine is also stored, but it might be in tissues and not the blood.

What tests are you planning on having? Iodine of course could affect the thyroid panel in some way.
Typically high vit C should be avoided, as it can affect some blood work results. I'd stop that for at least 3 days.

You will want a renal panel, to check your kidneys. That is important.