I was tested for serum b12 (results 292, were within range but very
much on the lower side) folic acid was 24 (the upper end is supposed
to be 17). I had been taking 10mg folic acid daily so the folic acid
results are skewed but apparently it seems b12 results also get 
masked if one is taking folic acid.
My question is, for how long do I have to stop taking folic acid
before getting tested again for serum b12 and folic, to make sure the
folic acid intake does not mask the results (i.e. to allow the excess
folic acid to be eliminated from the blood)

Hello Myq,


   The short answer is, a few days. Folic acid (folate) is water
soluble, and as such, is not stored in large quantities, in the body
as are fat soluble nutrients.


Normal ranges for Vitamin B12 in the US are 200-900 pg/ml. Your result is normal.

Normal Ranges for Folic Acid (Folate) are 2.7 ? 17 Your result is
slightly elevated.


   ?Drugs that can decrease folate measurements include alcohol,
aminosalicylic acid, birth control pills, estrogens, tetracyclines,
ampicillin, chloramphenicol, erythromycin, methotrexate, penicillin,
aminopterin, phenobarbital, phenytoin, and antimalarials.?

Because folic acid is water soluble, it will be quickly eliminated by
the body, and not stored as fat soluble nutrients are. In fact, taking
excessive folic acid supplements can cause you to manifest symptoms of
a B12 deficiency.

http://health.allrefer.com/health/vitamin-b-12-level-values.html

http://health.allrefer.com/health/folic-acid-test-values.html

http://health.allrefer.com/health/folic-acid-test-consider.html



   Vitamin B12, as well as intrinsic factor found in the intestine, is
needed for the body to utilize folic acid, but it does not ?mask? or
interfere with the actual testing of folic acid. The RBC  (red cell)
test is the most accurate overview than serum. Even then, an elevated
folate from diet or tablets would only last a short time (undefined)
per this site:

?Folic acid determinations can be made on either the liquid (plasma or
serum) or cellular (RBC) portion of blood. Serum folic acid levels are
influenced by short-term dietary variation. Quantitation of red cell
folic acid provides a better long-term measure of true tissue folic
acid levels. Because vitamin B12 is required in the uptake and
utilization of folic acid by the cells, in its absence folic acid is
trapped in the serum. Therefore, high serum folic acid levels may
occur in patients who have vitamin B12 deficiency. Strict vegetarian
diets may also elevate folic acid levels, but folic acid toxicity is
rare.?
http://www.dpcweb.com/medical/anemia/anemia_tests.html


?Folate intake from food is not associated with any health risk. The
risk of toxicity from folic acid intake from supplements and/or
fortified foods is also low [65]. It is a water soluble vitamin, so
any excess intake is usually excreted in urine. There is some evidence
that high levels of folic acid can provoke seizures in patients taking
anti-convulsant medications [1]. Anyone taking such medications should
consult with a medical doctor before taking a folic acid supplement.?
?There is no health risk, and no UL, for natural sources of folate found in food.?
http://ods.od.nih.gov/factsheets/folate.asp#h10



?A healthy individual has about 500-20,000 mcg of folate in body
stores. Humans need to absorb approximately 50-100 mcg of folate per
day in order to replenish the daily degradation and loss through urine
and bile. Otherwise, signs and symptoms of deficiency can manifest
after 4 months.

Frequency: 
?	In the US: The current standard of practice maintains that serum
folate levels less than 3 ng/mL and red blood cell (RBC) folate level
less than 140 ng/mL puts the individual at high risk of folate
deficiency. The RBC folate level generally indicates folate stored in
the body, whereas the serum folate level tends to reflect acute
changes in folate intake. Data from the Second National Health and
Nutrition Examination Survey indicate that 10% of the US population
may have low folate stores.



?How is it used?
B12 and folate are primarily ordered to help diagnose the cause of
macrocytic anemia. They are ordered as follow-up tests when large RBCs
and a decreased hemoglobin concentration are found during a CBC test.
Folate, B12, and an assortment of other tests may be ordered to help
evaluate the general health and nutritional status of a patient with
signs of significant malnutrition or malabsorption. This may include
those with alcoholism and those with disorders associated with
malabsorption such as celiac disease, Crohn?s disease, and cystic
fibrosis. B12 and folate may also be ordered to help diagnose the
cause of mental or behavioral changes, especially in the elderly.
B12 may be ordered with folate, by itself, or with other screening
laboratory tests ? such as a CMP (comprehensive metabolic panel) ? to
help diagnose the cause of neuropathy?
http://www.labtestsonline.org/understanding/analytes/vitamin_b12/test.html

You can safely repeat your lab tests for accurate results within a few
days of stopping your folic acid supplements.

A non-pregnant, non-lactating female, or any male should not exceed
1000 mcg of folic acid per day. Pregnant women and women expecting to
become pregnant are advised to comsume a diet high in folic acid.  If
you eat a healthy diet, and are not pregnant, or your doctor did not
prescribe folic acid supplements, you do not need a supplement.


Please request an Answer Clarification and allow me to respond, if any
part of this answer is unclear. I will be happy to assist you further
on this question, before you rate.

Regards, Crabcakes



Search Terms
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serum B12 parameters
elevated B12
Interfering subtances + serum B12
Interfering substances + folate
serum folate parameters