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September 25, 2020
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Does a Normal Vitamin B12 Level Exclude the Diagnosis of Pernicious Anemia?

Sometimes vitamin B12 levels are found to be normal or elevated in patients in whom you would expect them to be low (or even very low) because Intrinsic Factor Antibodies (IFA) have been detected in the blood test - and these are regarded as diagnostic of Pernicious Anemia. How could this be? Intrinsic Factor Antibodies are found in 40-80% of people with Pernicious Anemia and sometimes they not only bind to natural IF preventing it from binding to vitamin B12, or preventing the B12-IF complex from binding to the B12 receptor, but they can also bind to the reagent IF used in the immunoassays (blood tests) and this can give a falsely elevated result. Sometimes even a B12 level above normal.

There is a trick that the lab can do to deactivate the IF antibodies and when the blood sample is tested again, it will show the true (and often very low) result. So, when a normal or elevated vitamin B12 doesn't seem to fit with the clinical diagnosis of Pernicious Anemia, then other tests can be done, like measuring the MMA (in blood or urine) to determine what the cellular vitamin B12 status is and if elevated, is a much more reliable indicator of deficiency.

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Words You May Not Know
Antibodies
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Antibodies

An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include microorganisms (bacteria, fungi, parasites, and viruses) and chemicals. Antibodies may be produced when the immune system mistakenly considers healthy tissue a harmful substance. This is called an autoimmune disorder. Each type of antibody is unique and defends the body against one specific type of antigen.

Antigen

A substance that the immune system perceives as being foreign or dangerous. The body combats an antigen with the production of an antibody.

Intrinsic Factor
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Intrinsic Factor

Intrinsic factor is a protein that helps your intestines absorb vitamin B12. It is made by cells in the stomach lining.Intrinsic factor binds to vitamin B12. After attaching, intrinsic factor and B12 travel to the intestines to be absorbed into the bloodstream. Vitamin B12 is needed for red blood cells to form and grow‍‍

Methylmalonic Acid
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Methylmalonic Acid

Methylmalonic acid (MMA) is a compound that reacts with vitamin B-12 to produce coenzyme A (CoA). Coenzyme A is essential to normal cellular function. When vitamin B-12 deficiencies occur, methylmalonic acid levels increase.

MMA
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MMA

Methylmalonic acid (MMA) is a compound that reacts with vitamin B-12 to produce coenzyme A (CoA). Coenzyme A is essential to normal cellular function. When vitamin B-12 deficiencies occur, methylmalonic acid levels increase.

Immunoassay
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Immunoassay

A test that uses the binding of antibodies to antigens to identify and measure certain substances. Immunoassays may be used to diagnose disease.

Antigen

A substance that the immune system perceives as being foreign or dangerous. The body combats an antigen with the production of an antibody.

Reagent
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Reagent

A substance used to carry out a laboratory test. Reagents may be used in a chemical reaction to detect, measure, or make other substances.

Who Wrote This
Jonathan Bortz MD
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Jonathan’s background as a practicing diabetes specialist for 15 years and 17-year career developing nutritional prescriptive products for the pharmaceutical industry has contributed to his ability to understand nutrients, how they work and why they are important.

Over the years he has acquired broad and in-depth knowledge in minerals, essential fatty acids and other nutrients, but has special expertise in Vitamin B12 and choline metabolism. He is often asked to speak at national and international venues to articulate why B12, folate and choline are so important to gene function, brain development, liver and cardiovascular health. He applies pharmaceutical standards to nutrient science and has developed a unique ability to translate complicated concepts into simple promotional messages that resonate with practitioners and consumers. He has developed dozens of innovative nutritional products, of which many are category leaders in the US. Jonathan obtained his medical degree from the University of the Witwatersrand Medical School in South Africa and did his fellowship in Endocrinology at Washington University in St. Louis, MO.

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