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Vitamin B12 levels are tested in different ways with different accuracies.
Serum B12 by radioimmune assay (RIA) is less accurate than microbial assay since it picks up all forms of cobalamin including those that are inactive. Serum B12 by microbial assay appears to be the most widely used and is considered accurate. However, pregnancy, large doses of vitamin C, and folate deficiency may result in a falsely reduced B12 microbial assay. A 24-hour urine MMA (Methylmalonic acid) test is claimed to be very sensitive but is also more expensive. Without B12, MMA increases in the urine.
Another testing pattern used by doctors to determine vitamin B12 status is to test for intrinsic factor (IF) antibodies. Their presence prevents the normal binding of B12 to IF and thus prevents B12 absorbtion. Of pernicious anemia sufferers, 70% have these antibodies. If the test for IF antibodies is negative, a Schilling test is usually performed to help distinguish the nature of the problem. This test involves the use of radioactively labelled B12 and may be objectionable to some people.
A lack of gastric hydrochloric acid tends to confirm a suspected lack of intrinsic factor (IF), as both can be due to a shrinking of gastric cells.
Function
During the Schilling Test, the patient's B12 binding proteins are saturated by giving a large dose of unlabelled B12 intravenously. Absorption (via the ileum) of cobalamin is measured following ingestion of radioactively labelled B12.
In a normal system, more than 10% of the radioactive cobalamin will be excreted in the urine over 24hours. If less than 10% is excreted, the patient is given cobalamin + IF. If the patient is suffering from Pernicious Anemia, greater than 10% of the labelled cobalamin will appear in the urine within 24hours, otherwise the patient can be said to have an absorption problem.
Low results may occur in patient's with kidney problems.
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Test for B12 Levels can help with the following: | | | | | Autoimmune |  Multiple Sclerosis | The first step when you receive a diagnosis of multiple sclerosis is to determine if you really have it. A vitamin B12 deficiency has very similar symptoms and is frequently misdiagnosed as MS; the type of anemia resulting from B12 deficiency is called pernicious anemia. [Hosp Pract (Off Ed) 1995 Jul 15;30(7): pp.47-52; discussion 52, 54]
Additionally, researchers found in 45 MS patients that vitamin B12 levels were significantly lower in those who experienced the onset of first neurological symptoms prior to age 18 years (10 patients) compared to patients in whom the disease first manifested after age 18 (35 patients). In contrast, serum folate levels were unrelated to age of onset of the disease. As vitamin B12 levels were statistically unrelated to chronicity of illness, these findings suggest a specific association between the timing of onset of first neurological symptoms of MS and vitamin B12 metabolism. In addition, since vitamin B12 is required for the formation of myelin and for immune mechanisms, a deficiency in MS is of critical pathogenetic significance. [PMID: 8407160, UI: 94011702] |
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Circulation |
Megaloblastic Anemia / Pernicious Anemia| | A vitamin B12 deficiency is the most common cause of megaloblastic anemia. When testing facilities are not available or cannot be afforded, intramuscular or sublingual B12, with or without folic acid, can be used to see if symptoms improve.
If vitamin B12 deficiency is suspected, tests to measure the blood level of B12 are routine. Usually, the presence of the intrinsic factor (IF) is determined by testing for the presence of antibodies to the IF in the blood. Gastric analysis may be required to confirm the presence or absence of IF.
Taking a lot of folic acid may cover up the B12 anemia and other symptoms until it is too late for effective treatment with vitamin B12. Therefore, vitamin tablets of folic acid with over 400mcg have been taken off the market and are available by prescription only. If megaloblastic anemia occurs, both folic acid and vitamin B12 levels should be checked to assure proper treatment and follow-up. |
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Diet |
A Raw Food/Fruitarian Diet| | For raw-food vegans who have not been careful about consuming enough B12 (in the form of supplements or fortified foods), it would be wise to have B12 levels assessed and to commence dietary supplementation immediately. Some 80% of those who have been vegan for over 2 years have a functional B12 deficiency -- the figure for raw food vegans is almost certainly higher, unless they make a point of not excessively washing their fruits and vegetables. |
A Vegan Diet| | For longer-term vegans who have not been too careful about consuming enough B12 (in the form of supplements or fortified foods), it would be wise to have B12 levels assessed and to commence dietary supplementation immediately. Some 80% of people who have been vegan for over 2 years have a functional B12 deficiency, meaning their homocysteine is too high. |
 A Vegetarian Diet| | For longer-term vegetarians who have not been careful about consuming enough B12 (in the form of supplements or fortified foods), it may be wise to have B12 levels assessed and to consider dietary supplementation. About 25% of all ovo-lacto vegetarians have a functional B12 deficiency, meaning their homocysteine is too high. |
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Mental |
Obsessive-Compulsive Disorder (OCD)| | In one study of OCD patients, 20% had abnormally low serum vitamin B12 concentrations compared to the two control groups. [Acta Psychiatr Scand 78(1): 8-10, 1988.] |
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KEY | | May do some good | | | Highly recommended |
GLOSSARY
Anemia (Anaemia, Anemias)
A condition resulting from an unusually low number of red blood cells or too little hemoglobin in the red blood cells. The most common type is iron-deficiency anemia in which the red blood cells are reduced in size and number, and hemoglobin levels are low. Clinical symptoms include shortness of breath, lethargy and heart palpitations.
Antibody (Antibodies)
A type of serum protein (globulin) synthesized by white blood cells of the lymphoid type in response to an antigenic (foreign substance) stimulus. Antibodies are complex substances formed to neutralize or destroy these antigens in the blood. Antibody activity normally fights infection but can be damaging in allergies and a group of diseases that are called autoimmune diseases.
Chronic (Chronicity)
Usually referring to chronic illness: Illness extending over a long period of time.
Cobalamin (B12, B-12, Cobalamine, Vitamin B12)
Essential for normal growth and functioning of all body cells, especially those of bone marrow (red blood cell formation), gastrointestinal tract and nervous system, it prevents pernicious anemia and plays a crucial part in the reproduction of every cell of the body i.e. synthesis of genetic material (DNA).
Folic Acid
A B-complex vitamin that functions along with vitamin B-12 and vitamin C in the utilization of proteins. It has an essential role in the formation of heme (the iron containing protein in hemoglobin necessary for the formation of red blood cells) and DNA. Folic acid is essential during pregnancy to prevent neural tubular defects in the developing fetus.
Gastric
Of, relating to, or associated with the stomach.
Hydrochloric Acid (HCl)
An inorganic acidic compound, excreted by the stomach, that aids in digestion.
Ileum
The lower two-thirds of the small intestine, ending in the ileocecal valve and emptying into the cecum of the colon. The last foot of the ileum is the only absorption site available for important dietary substances such as vitamin B12, folic acid, some essential fatty acids, fat soluble vitamins, and recycled bile acids.
Intrinsic Factor
One of two proteins secreted from the lining of the stomach whose sole purpose is (it seems) to cradle B12 and carry it through the digestive system until it reaches the absorption sites in the last foot of small intestine. There it slips from one protein to the other, and into the cell membranes where its handed over to the specialized blood protein that can carry it safely to the final target tissues (3 times out of 4, the bone marrow). Apparently cyanocobalamin (B12) has "parts that fall off", radicals that twirl around in five directions on three charge potentials, and is generally not very durable.
Kidneys (Kidney, Renal)
Bean-shaped organs, each about the size of a fist. They are located near the middle of the back, just below the rib cage. The kidneys are sophisticated reprocessing machines, each day handling about 50 gallons of blood to sift out about half a gallon of waste products and extra water. The waste and extra water become urine, which flows to the bladder through tubes called ureters. The actual filtering occurs in tiny units inside the kidneys called nephrons. Every kidney has about a million nephrons. In a nephron, a glomerulus -- which is a tiny blood vessel, or capillary -- intertwines with a tiny urine-collecting tube called a tubule. A complicated chemical exchange takes place, as waste materials and water leave your blood and enter your urinary system. The kidneys recycle chemicals such as sodium, phosphorus, and potassium and thus regulate their levels. Renal: Pertaining to the kidneys.
Megaloblast (Megaloblastic, Megaloblasts)
An abnormally large nucleated red blood cell found especially in people having pernicious anemia or certain vitamin deficiencies.
Metabolism (Metabolic, Metabolize, Metabolizes, Metabolizing)
The chemical processes of living cells in which energy is produced in order to replace and repair tissues and maintain a healthy body. Responsible for the production of energy, biosynthesis of important substances, and degradation of various compounds. Also defined as the sum total of changes in an organism in order to achieve a balance (homeostasis): Catabolic burns up, anabolic stores and builds up; the sum of their work is metabolism.
Microgram (mcg, Micrograms, ug)
0.000001 or a millionth of a gram.
Multiple Sclerosis (MS)
Demyelinating disorder of the central nervous system, causing patches of sclerosis (plaques) in the brain and spinal cord, manifested by loss of normal neurological functions, e.g. muscle weakness, loss of vision, and mood alterations.
Myelin
A substance made of protein and lipid (fat) that protects the nerves, especially in the brain. The myelin sheath is a jacket of insulation around axons to help them conduct their electrical discharges quickly down the axon.
Obsessive-Compulsive Disorder (Obsessive Compulsive, Obsessive-Compulsive, OCD)
Those suffering from OCD have obsessions and/or compulsions. Obsessions refer to recurrent and persistent thoughts, impulses, or images that are intrusive and cause severe anxiety or distress. Compulsions refer to repetitive behaviors and rituals (such as hand washing, hoarding, ordering, checking) or mental acts (like counting, repeating words silently, avoiding). These obsessions and compulsions significantly interfere with normal routine, functioning, social activities and relationships.
Pernicious Anemia
Anemia caused by a vitamin B12 deficiency.
Protein (Proteins)
Compounds composed of hydrogen, oxygen, and nitrogen present in the body and in foods that form complex combinations of amino acids. Protein is essential for life and is used for growth and repair. Foods that supply the body with protein include animal products, grains, legumes, and vegetables. Proteins from animal sources contain the essential amino acids. Proteins are changed to amino acids in the body.
Serum
The cell-free fluid of the bloodstream. It appears in a test tube after the blood clots and is often used in expressions relating to the levels of certain compounds in the blood stream.
Sublingual (Sublingually)
Situated or administered under the tongue, for example sublingual glands or sublingual tablets.
Urine MMA
The current gold standard for properly diagnosing B12 deficiency is the Urine MMA Level, due to the lack of sensitivity of the serum B12 test. The serum B12 test may produce false "normal" or "high" indications because of inactive B12 analogs in the blood from foods such as sea vegetables, or due to a body's last ditch dump from its bone marrow stores in response to severe deficiency. Available by mail from Norman Clinical Laboratories.
Vegan (Veganism, Vegans)
A person who consumes no animal products of any kind. In other words, vegans do not consume meat, fish, fowl, dairy products, eggs, honey, or products containing gelatin or any other animal-derived ingredients such as whey powder or food colorings.
Vegetarian (Lacto-Ovo-Vegetarian, Vegetarianism, Vegetarians)
A person who consumes no meat, fish or fowl (chicken, turkey, etc.), but who may consume animal products such as dairy products (milk, cheese, butter, etc.), eggs or honey.
Vitamin C (Ascorbic Acid)
A water-soluble antioxidant vitamin essential to the body's health. When bound to other nutrients, for example calcium, it would be referred to as "calcium ascorbate". As an antioxidant, it inhibits the formation of nitrosamines (a suspected carcinogen). Vitamin C is important for maintenance of bones, teeth, collagen and blood vessels (capillaries), enhances iron absorption and red blood cell formation, helps in the utilization of carbohydrates and synthesis of fats and proteins, aids in fighting bacterial infections, and interacts with other nutrients. It is present in citrus fruits, tomatoes, berries, potatoes and fresh, green leafy vegetables.
Last updated: May 26, 2008
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