"Why is B12 deficiency so under-diagnosed?
B12 deficiency is often missed for two reasons. First, it’s not routinely tested by most physicians. Second, the low end of the laboratory reference range is too low. This is why most studies underestimate true levels of deficiency. Many B12 deficient people have so-called “normal” levels of B12.
Yet it is well-established in the scientific literature that people with B12 levels between 200 pg/mL and 350 pg/mL – levels considered “normal” in the U.S. – have clear B12 deficiency symptoms. Experts who specialize in the diagnosis and treatment of B12 deficiency, like Sally Pacholok R.N. and Jeffery Stewart D.O., suggest treating all patients that are symptomatic and have B12 levels less than 450 pg/mL. They also recommend treating patients with normal B12, but elevated urinary methylmalonic acid (MMA), homocysteine and/or holotranscobalamin (other markers of B12 deficiency)."
Excerpt from Chris Kresser's article: B12 deficiency: a silent epidemic with serious consequences.
Hi cailleach.
You double posted-it is OK, we have all done this one time or another- so I copied and pasted my original reply with one small correction*.
Your neurological B12 (methylocobalamin) and your neurological folate (tetrahydrofolate or methylfolate) are likely low, indicating undermethylation
issues.
These will not show on standard MMA tests.
Since homocysteine serum levels tend to fluctuate, you will need a
CFS homosysteine test for greater accuracy, but personally I'd do a methylfolate* (corrected as I had typed methyfolate originally) and methylocobalamin trial instead.
What are your symptoms?
Best wishes.
Niko