Screening for Vitamin B-12 Deficiency

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May 28, 2003 | 31,752 views

Vitamin B-12 deficiency can be difficult to diagnose clinically,as its symptoms are often nonspecific including:

Moreover, symptoms vary and often don’t include the classicsignals such as:

Standard tests to assess vitamin B-12 concentrations are limitedbecause the clinical severity of vitamin B-12 deficiency is unrelatedto vitamin B-12 concentrations.

Accurate identification of vitamin B-12 deficiency is importantfor a number of reasons. For example, macrocytic anemia, which canbe a signal of vitamin B-12 deficiency, may also be caused by folatedeficiency. The anemia may have different neurologic features dependingon the cause. Therefore, inappropriately treating the conditionwith folic acid will correct the hematologic signs of vitamin B-12deficiency but will not address the neurologic symptoms.

Vitamin B-12 deficiency results in elevated serum concentrationsof methylmalonic acid (MMA); therefore elevated concentrations ofMMA have been suggested to indicate vitamin B-12 deficiency.

However, there is no consensus on cut-off levels of MMA to useto define vitamin B-12 deficiency among elderly people. Among thisgroup, impaired renal function can be an important confounding factor.

Both vitamin B-12 deficiency and folate deficiency are common amongolder people.

In one study, MMA of less than 200 pmol/L was used to define individualsas being at high risk of vitamin B-12 deficiency.

However, 15 percent to 30 percent of people with high vitamin B-12concentrations also had elevated MMA concentrations, which indicatesthat elevated MMA is not always a reliable indicator.

Instead, the ultimate indicator for vitamin B-12 deficiency maybe the reduction in MMA concentrations and improvement in clinicalsymptoms after being treated with vitamin B-12.

Researchers gave the following recommendation for a more reliablescreening of vitamin B-12 deficiency: If vitamin B-12 concentrationis less than 150 pmol/L, more detailed investigation is requiredto find an underlying cause and treatment. If vitamin B-12 concentrationis between 150 and 200 pmol/L, then use of MMA may help to identifythose who require more detailed investigation and treatment.

AmericanJournal of Clinical Nutrition May, 2003;77(5):1241-7 (Free FullText Article)

This is an excellent study that provides one of the most currentassessments on how to scientifically document vitamin B-12 deficiency.

This is the approach you could use if you were compelled toknow for certain that there was a B-12 defiency. However, if youlook at the big picture it would seem more than reasonable to givea therapeutic trial of B-12 and see if the symptoms improve.

This is more than reasonable considering that B-12 is virtuallynon-toxic and very inexpensive. This approach would likely costless than 90 percent of the cost of the test, and even if one didthe test, it is common to challenge the results with this type oftherapeutic trial as discussed in the article.

So what type of B-12 can you use?

As I said in the past:

It is important to know that most oral vitamin B-12 supplementsdo not work well at all. Vitamin B-12 is the largest known vitamin;it is a very large molecule, and it is not easily absorbed. Yourbody has developed a very sophisticated system to absorb B-12, whichinvolves the production of intrinsic factor in the stomach thatattaches to the B-12 and allows it to be absorbed in the end ofthe small intestine.

If your stomach lining is damaged from an ulcer or a Helicobacterinfection, you will not produce intrinsic factor very well, andyou will not be able to absorb B-12 very well, if at all. An imbalanceof bacteria in the small intestine can also produce impaired absorption,as would removal of a portion of the small intestine (commonly donein Crohn's disease).

Vitamin B-12 deficiency is quite common in vegetarians and veganswho do not supplement with B-12 or use fortified foods, since B-12is not readily available, if available at all, in plants. If youare a vegetarian who eats eggs or fish, the risk for B-12 deficiencyis considerably reduced, though you should still consider B-12 supplementation.If you are a vegan avoiding all animal products, and you do notalready supplement with B-12 (it seems many already do), you shouldseriously consider it.

So, if you suspect you are deficient in vitamin B-12, I wouldencourage you to obtain your B-12 in a more absorbable form. Thecommon recommendation is to use injections. My recommendation forthat would be to use 1 ml once a day for two weeks and then threetimes a week until the 30-ml bottle is finished.

An alternative to the injections would be to use DMSOand vitamin B12. The DMSO causes the B12 to be absorbed verysimilarly to an injection without the cost or pain of a needle.Intranasal B12 isalso available, but unless you have a prescription card I wouldnot recommend it, as it is VERY expensive.

One strong inhibitor of vitamin B-12 absorption is the verypopular drug Prilosec (omeprazole), which has been clearly shownto decreaseB-12 absorption.

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