Hey ,
I usually recommend my clients to value urine tests above serum tests, new values above old values and I would look at them through the lens of how I felt around the measurements. Another factor to consider is that different labs use different equipment which makes different errors (I am saying this as an ex-physics and astronomy student). Labs can even use slightly different reference ranges.
That being said I don’t think these differences in results tell a totally different story.
Even if the levels on your serum are in the upper part of the reference range, I would not add it to the list ‘yet another thing that goes wrong in my body’.
From earlier lab reports we saw some elevations in mercury. Mercury can bind to serum B12 leaving it unavailable for the cell. Through this lens, these results are actually good. Be aware that B vitamins also are needed for detoxification and can help free up stored mercury. This in theory could also lead to fluctuations in MMA.
The focus is on reducing inflammation, supporting liver and gut function, get iron & folate up. Getting your body strong enough for active detoxification. Bernadette posted some really good tips for general detoxification in a post called ‘Mineral Balance’. You could take a look there and implement things you aren’t doing yet.
But I would wait to help the body actively detoxify to a later stage.