Vitamin B12 and Folate

Send Us Your Feedback
  • Also Known As:
  • Cobalamin
  • Folic Acid
  • RBC Folate
  • Folacin
  • Vitamin B9
  • Formal Name:
  • Vitamin B12
  • Folate
Medically Reviewed by Expert Board

This page was fact checked by our expert Medical Review Board for accuracy and objectivity. Read more about our editorial policy and review process.

.
This article was
last modified The modified date indicates that one or more changes were made to the article. Such changes may or may not result from a full review of the article, so the two dates may not always agree.
on.
Learn more about...
Healthy Aging

At a Glance

Why Get Tested?

To help diagnose one cause of anemia or neuropathy; to evaluate nutritional status in some people; to monitor the effectiveness of treatment for vitamin B12 or folate deficiency

When To Get Tested?

When you have abnormal results on a complete blood count (CBC) with a blood smear showing large red blood cells (macrocytosis) or abnormal (hypersegmented) neutrophils; when you have symptoms of anemia (weakness, tiredness, pale skin) and/or of neuropathy (tingling or itching sensations, eye twitching, memory loss, altered mental status); when you are being treated for vitamin B12 or folate deficiency

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

Biotin found in certain dietary supplements may interfere with testing. Certain medicines, such as cholchicine, neomycin, para-aminosalicylic acid, and phenytoin, may affect the test results; your healthcare provider will advise you on which ones to stop taking. Ask your healthcare practitioner or lab for specific instructions.

Looking to get tested?

More than 500+ lab tests available online - confidential, convenient and affordable; no doctor’s referral needed, no insurance required

  • Secure and Confidential Results
  • No Insurance or Referral Needed
  • Affordable Pricing including Doctor's Order
  • 100% Satisfaction Guarantee
Order Test Now Powered by HealthTestingCenters.com
BBB Accredited Business A+ Rating HSA and FSA Cards Accepted Trusted Site, Certified and Secure
  • 1
    Order Your Test

    Online or over the phone, no doctor's referral needed
  • 2
    Find a Lab Near You

    Over 3,500 locations to choose from
  • 3
    Get Your Results

    Most test results sent directly to you in 1-2 days
You can order your own FDA approved laboratory testing online or by phone and walk-in to a local lab location with a lab requisition to have your testing services performed. Direct-access laboratory testing provides the same FDA approved tests ordered by your physician from the same CLIA certified laboratories. You pay private-pay prices with a credit card, online checkout is easy. There are no additional fees for lab services or blood work. We do not bill your health insurance company.

Looking For Test Results?

Looking For Reference Ranges?

You may be able to find your test results on your laboratory’s website or patient portal. However, you are currently at Lab Tests Online. You may have been directed here by your lab’s website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab’s website or portal, or contact your healthcare practitioner in order to obtain your test results.

Lab Tests Online is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called “normal” values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are “within normal limits.”

For more information, please read the article Reference Ranges and What They Mean.

What is being tested?

Vitamin B12 and folate are two vitamins that are part of the B complex of vitamins. B12 and folate work with vitamin C to help the body make new proteins. They are necessary for normal red blood cell (RBC) and white blood cell (WBC) formation, repair of tissues and cells, and synthesis of DNA. Both are nutrients that cannot be produced in the body and must be supplied by the diet.

Vitamin B12 and folate tests measure vitamin levels in the liquid portion of the blood (serum or plasma) to detect deficiencies. Sometimes the amount of folate inside red blood cells may also be measured.

  • Vitamin B12, also called cobalamin, is found in foods from animals, such as red meat, fish, poultry, milk, yogurt, and eggs.
  • Folate (Vitamin B9) refers to a natural occurring form of the vitamin, whereas folic acid refers to the supplement added to foods and drinks. Folate is found in leafy green vegetables, citrus fruits, dry beans and peas, liver, and yeast.

In recent years, fortified cereals, breads, and other grain products have also become important dietary sources of B12 and folate (identified as “folic acid” on nutritional labels).

A deficiency in either B12 or folate can lead to macrocytic anemia, where red blood cells are larger than normal. Megaloblastic anemia, a type of macrocytic anemia, is characterized by the production of fewer but larger RBCs called macrocytes, in addition to some cellular changes in the bone marrow. Other laboratory findings associated with megaloblastic anemia include decreased WBC count, RBC count, reticulocyte count, and platelet count.

B12 is also important for nerve health and a deficiency can lead to varying degrees of neuropathy, nerve damage that can cause tingling and numbness in the affected person’s hands and feet.

Folate is necessary for cell division such as is seen in a developing fetus. Folate deficiency during early pregnancy can increase the risk of neural tube defects such as spina bifida in a growing fetus.

B12 and folate deficiencies are most often caused by not getting enough of the vitamins through the diet or supplements, long-term use of certain medications, inadequate absorption, or by increased need as seen in pregnancy:

  • Dietary deficiencies—these are uncommon in the United States because many foods and drinks are supplemented with these vitamins, which are stored by the body. Adults typically have several years’ worth of vitamin B12 stored in the liver and about 3 months of stored folate. Dietary deficiencies do not usually cause symptoms until stores of the vitamins within the body have been depleted. B12 deficiencies are sometimes seen in vegans (those who do not consume any animal products) and in their breast-fed infants.
  • Inadequate absorption—vitamin B12 absorption occurs in a series of steps. B12 is normally released from food by stomach acid and then, in the small intestine, is bound to intrinsic factor (IF), a protein made by parietal cells in the stomach. This B12-IF complex is then absorbed by the small intestine, bound by carrier proteins (transcobalamins), and enters the circulation. If a disease or condition interferes with any of these steps, then B12 absorption is impaired.
  • Increased need—this can be seen with a variety of diseases and conditions. Increased demand for folate occurs when a woman is pregnant or nursing, in early childhood, with cancers, or with chronic hemolytic anemias.

For more, see the article on Vitamin B12 and Folate Deficiencies.

 

Common Questions

How is the test used?

Vitamin B12 and folate are separate tests often used together to:

  • Detect low levels (deficiencies)
  • Diagnose the cause of certain anemias, such as pernicious anemia, an autoimmune disease that affects the absorption of B12
  • Help determine the cause of an altered mental state or other behavioral changes, especially in the elderly
  • Help determine the cause of signs and symptoms of a condition affecting nerves (neuropathy)
  • Evaluate your general health and nutritional status if you have signs and symptoms of significant malnutrition or dietary malabsorption.
  • Monitor the effectiveness of treatment with vitamin B12 and folate supplements; this is especially true for those who cannot properly absorb B12 and/or folate and must have lifelong treatment.

Serum folate levels can vary based on a person’s recent diet. Because red blood cells store 95% of circulating folate, a test to measure the folate level within RBCs may be used in addition to the serum test. Some healthcare practitioners feel that the RBC folate test is a better indicator of long-term folate status and is more clinically relevant than serum folate, but there is not widespread agreement on this.

When is it ordered?

B12 and folate levels may be ordered when a complete blood count (CBC) and/or blood smear, done as part of a health checkup or an evaluation for anemia, shows a low red blood cell (RBC) count, decreased hemoglobin and hematocrit, and the presence of large RBCs. Specifically, a high RBC mean corpuscular volume (MCV) indicates that the RBCs are enlarged. In addition to enlarged RBCs on the blood smear, the nucleus of white cell neutrophils show many segments (hypersegmented neutrophils), a classic sign frequently observed.

Testing for B12 and folate levels may be ordered when you have signs and symptoms of a deficiency, such as:

  • Diarrhea
  • Dizziness, trouble walking
  • Fatigue, muscle weakness
  • Loss of appetite
  • Pale skin
  • Rapid heart rate, irregular heartbeats
  • Shortness of breath
  • Sore tongue and mouth
  • Tingling, numbness, and/or burning in the feet, hands, arms, and legs (with B12 deficiency)
  • Confusion or forgetfulness
  • Paranoia, irritability

B12 and folate testing may sometimes be ordered when you have a condition that puts you at risk of a deficiency.

These tests may be ordered on a regular basis when you are treated for malnutrition or a B12 or folate deficiency. For individuals with a condition causing a chronic deficiency, this may be part of a long-term treatment plan.

What does the test result mean?

Normal B12 and folate blood levels may mean that you do not have a deficiency and that your signs and symptoms are likely due to another cause. However, normal levels may reflect the fact that your stored B12 and/or folate have not yet been fully depleted.

When a B12 level is normal or low normal but a deficiency is still suspected, a healthcare practitioner may order a methylmalonic acid (MMA) test as an early indicator of B12 deficiency.

A low B12 and/or folate level means that you have a deficiency. Additional tests are usually done to investigate the underlying cause of the deficiency. Some causes of low B12 or folate include:

  • Conditions that interfere with their absorption in the small intestine. These may include:
    • Pernicious anemia, the most common cause of B12 deficiency
    • Celiac disease and tropical sprue
    • Inflammatory bowel disease, including Crohns disease and ulcerative colitis
    • Bacterial overgrowth or the presence of parasites, such as tapeworms, in the intestines
    • Reduced stomach acid production from long-term (more than one year) use of antacids or H2 receptor blockers or proton pump inhibitors
    • Surgery that removes part of the stomach, such as gastric bypass, or the intestines may greatly decrease absorption.
    • Pancreatic insufficiency (exocrine pancreatic insufficiency) – the pancreas is not able to produce enough digestive enzymes to break down food.
  • Dietary deficiency of folate or B12—this is uncommon in the U.S. However, it may be seen with general malnutrition, in the elderly and in vegans who do not consume any animal products. With the introduction of fortified cereals, breads, and other grain products, folate deficiency is very rare.
  • Heavy drinking or chronic alcoholism
  • Use of some drugs such as metformin, omeprazole, methotrexate or anti-seizure medications such as phenytoin
  • Increased need—all pregnant women need increased amounts of folate for proper fetal development and are recommended to take 400 micrograms of folic acid per day. People with cancer that has spread (metastasized) or with chronic hemolytic anemia have increased need for folate.
  • Smoking

For additional information, see the article Vitamin B12 and Folate Deficiencies.

If a person with a B12 or folate deficiency is being treated with supplements (or with B12 injections), then normal or elevated results indicate a response to treatment.

High levels of B12 are uncommon and not usually clinically monitored. However, if someone has a condition such as chronic myeloproliferative neoplasm, diabetes, heart failure, obesity, AIDS, or severe liver disease, then that person may have an increased vitamin B12 level. Ingesting estrogens, vitamin C or vitamin A can also cause high B12 levels.

What other tests might be done?

Additional laboratory tests may be used to help diagnose pernicious anemia, the most common cause of B12 deficiency. These include intrinsic factor antibody and parietal cell antibody. The presence of these autoimmune antibodies indicates that a B12 deficiency is likely due to the destruction of parietal cells in the stomach, leading to a decreased ability to absorb B12 from the diet.

Other laboratory tests that may be used to help detect B12 and folate deficiencies include homocysteine and methylmalonic acid (MMA). Homocysteine and MMA are elevated in B12 deficiency while only homocysteine, and not MMA, is elevated in folate deficiency. This distinction is important because giving folate to someone who is B12-deficient will treat the anemia but does not treat the neurologic damage, which may be irreversible.

When you have signs and symptoms of neuropathy, a B12 test may be ordered with folate, by itself, or with other screening laboratory tests, such as a complete blood count (CBC), comprehensive metabolic panel (CMP), antinuclear antibody (ANA), C-reactive protein (CRP), and rheumatoid factor (RF).

Is there anything else I should know?

If a person is deficient in both B12 and folate but only takes folic acid supplements, the B12 deficiency may be masked. The anemia associated with both may be resolved, but the underlying neuropathy will persist.

Intrinsic factor antibodies can interfere with the vitamin B12 test, producing falsely elevated results. If a person has these antibodies in their blood, the results of their B12 test must be interpreted with caution.

Since folate deficiency is rarely seen in the U.S., some laboratories no longer offer the folate test. Your sample may need to be sent to a reference laboratory.

Can taking too many vitamin B12 and folic acid supplements hurt me?

Not usually. B12 and folic acid are water-soluble, thus the body will rid itself of any excess by eliminating it in the urine. However, taking folic acid can mask low B12 levels, so it can be important to be tested for both before beginning folate supplementation. Individuals who are allergic to cobalt should not take B12, and those with the hereditary eye disease Leber’s disease may experience harm to the optic nerve if they take B12

Should everyone have vitamin B12 and folate tests?

These tests are generally not necessary if you do not have symptoms associated with a deficiency, you do not have large red blood cells (RBCs) as determined by a complete blood count (CBC), or you do not have a disease or condition associated with malabsorption.

Should every pregnant woman have a folate test?

Folate levels may be tested during prenatal checkups. Folate supplementation is generally recommended for women before and during pregnancy.

Can I have B12 and folate tests done in my doctor's office?

These tests require specialized equipment and are typically performed in a laboratory.

Related Content

On This Site

Elsewhere on the Web

View Sources

Sources Used for Current Review

Frank, E. and Straseski, J. (2019 June, Updated). Megaloblastic Anemia. ARUP Consult. Available online at https://arupconsult.com/content/megaloblastic-anemia. Accessed on 9/6/2019.

Singh, N. et. al. (2018 October 22, Updated). Vitamin B-12 Associated Neurological Diseases. Medscape Neurology. Available online at https://emedicine.medscape.com/article/1152670-overview. Accessed on 9/6/2019.

(© 1995-2019). Vitamin B12 and Folate, Serum. Mayo Clinic Laboratories. Available online at https://www.mayocliniclabs.com/test-catalog/Clinical+and+Interpretive/9156. Accessed on 9/6/2019.

Ghadban, R. et. al. (2018 December 27, Updated). Folate (Folic Acid). Medscape Laboratory Medicine. Available online at https://emedicine.medscape.com/article/2085523-overview. Accessed on 9/6/2019.

(2019 July 9, Updated). Vitamin B12. National Institutes of Health Office of Dietary Supplements. Available online at https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/. Accessed on 9/6/2019.

Folic acid – test. MedlinePlus Medical Encyclopedia. Available online at https://medlineplus.gov/folicacid.html. Accessed on 9/6/2019.

Nagalla, S. and Schick, P. (2019 February 19, Updated). Pernicious Anemia. Medscape Hematology. Available online at https://emedicine.medscape.com/article/204930-overview. Accessed on 9/6/2019.

(2019 July 11, Updated). Folate. National Institutes of Health Office of Dietary Supplements. Available online at https://ods.od.nih.gov/factsheets/Folate-Consumer/. Accessed on 9/6/2019.

(2019 April 1, Updated). Folic acid. Office on Women’s Health. Available online at https://www.womenshealth.gov/a-z-topics/folic-acid. Accessed on 9/6/2019.

Sources Used for Previous Review

Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Cohen, E. (2003 April 25). Medical Encyclopedia: Folate-deficiency anemia. MedlinePlus Health Information, Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000551.htm.

Brose, M. (2003 June 1). Medical Encyclopedia: Folic acid – test. MedlinePlus Health Information, Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003686.htm.

Angelo, S. (2003 January 19). Medical Encyclopedia: Folic acid (folate). MedlinePlus Health Information, Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/002408.htm.

Angelo, S. (2003 January 18). Medical Encyclopedia: Vitamin B12. MedlinePlus Health Information, Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/002403.htm.

Folate, RBC and Serum. ARUP’s Guide to Clinical Laboratory Testing. Available online at http://www.aruplab.com/guides/clt/tests/clt_a237.jsp#1149156.

Intrinsic Factor Blocking Antibody. ARUP’s Guide to Clinical Laboratory Testing. Available online at http://www.aruplab.com/guides/clt/tests/clt_a23b.jsp#1152989.

Vitamin B12. ARUP’s Guide to Clinical Laboratory Testing. Available online at http://www.aruplab.com/guides/clt/tests/clt_259c.jsp#1150535.

Vitamin B12 Binding Capacity. ARUP’s Guide to Clinical Laboratory Testing. Available online at http://www.aruplab.com/guides/clt/tests/clt_260c.jsp#1150556.

Stevenson, R. Spina bifida. AccessMed Health Information Library, Hendrick Health System. Available online at http://www.ehendrick.org/healthy/001280.htm.

Carson-DeWitt, R. Pernicious anemia. AccessMed Health Information Library, Hendrick Health System. Available online at http://www.ehendrick.org/healthy/001049.htm.

Haggerty, M. Folic acid deficiency anemia. AccessMed Health Information Library, Hendrick Health System. Available online at http://www.ehendrick.org/healthy/000554.htm.

Patience Paradox. Folic acid. AccessMed Health Information Library, Hendrick Health System. Available online at http://www.ehendrick.org/healthy/002072.htm.

Haggerty, M. Anemias. AccessMed Health Information Library, Hendrick Health System. Available online at http://www.ehendrick.org/healthy/.

Vitamin B12. NIH Clinical Center, Facts About Dietary Supplements. Available online at http://www.cc.nih.gov/ccc/supplements/intro.html.

Folate. NIH Clinical Center, Facts About Dietary Supplements. Available online at http://www.cc.nih.gov/ccc/supplements/intro.html.

Johnson, L. Vitamin B12. Merck Manual Second Home Edition, Section 12. Disorders of Nutrition and metabolism, Chapter 154. Vitamins. Available online at http://www.merck.com/pubs/mmanual_home2/sec12/ch154/ch154j.htm.

Johnson, L. Folic Acid. Merck Manual Second Home Edition, Section 12. Disorders of Nutrition and metabolism, Chapter 154. Vitamins. Available online at http://www.merck.com/pubs/mmanual_home2/sec12/ch154/ch154k.htm.

(2003 October). Vitamin B-12. Familydoctor.org. Available online at http://familydoctor.org/765.xml.

Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby’s Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 460-461, 999-1000, 834-836.

Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry, AACC Press, Washington, DC. Pp 405-406.

Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. 1124-1127, 410-413.

Levin, M. (2007 March 13, Updated). Vitamin B12 level. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003705.htm. Accessed on 1/30/08.

Matsui, W. (2007 February 14, Updated). Anemia B12 deficiency. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000574.htm. Accessed on 1/30/08.

Grund, S. (2007 August 27, Updated). Pernicious Anemia. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000569.htm. Accessed on 1/30/08.

Van Voorhees, B. (2006 October 17, Updated). Folate Deficiency. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000354.htm. Accessed on 1/30/08.

(Reviewed 2011 April 4). Vitamin B12. MedlinePlus Drug Information [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/druginfo/natural/926.html. Accessed August 2011.

(Reviewed 2011 June 24). Dietary Supplement Fact Sheet: Vitamin B12. NIH Office of Dietary Supplements [On-line information]. Available online at http://ods.od.nih.gov/factsheets/VitaminB12-QuickFacts/. Accessed August 2011.

Mayo Clinic Staff (2011 March 4). Vitamin Deficiency Anemia. MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/health/vitamin-deficiency-anemia/DS00325/METHOD=print. Accessed July 2011.

(Revised 2011 April). Pernicious Anemia. National Heart Lung and Blood Institute [On-line information]. Available online at http://www.nhlbi.nih.gov/health/dci/Diseases/prnanmia/prnanmia_what.html. Accessed August 2011.

Chen, Y. (Updated 2010 January 31). Anemia – B12 deficiency. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000574.htm. Accessed August 2011.

Schick, P. (Updated 2011 May 26). Megaloblastic Anemia. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/204066-overview. Accessed August 2011.

Frank, E. et. al. (Updated 2010 September). Megaloblastic Anemia. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/MegaloblasticAnemia.html. Accessed July 2011.

Conrad, M. (Updated 2011 May 26). Pernicious Anemia. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/204930-overview. Accessed August 2011.

Dugdale, D. (Updated 2008 November 23). Pernicious anemia. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000569.htm. Accessed August 2011.

OH, R. and Brown, D. (2003 March 1). Vitamin B12 Deficiency. Am Fam Physician. 2003 Mar 1;67(5):979-986. [On-line information]. Available online at http://www.aafp.org/afp/2003/0301/p979.html. Accessed August 2011.

Pagana, K. D. & Pagana, T. J. (© 2011). Mosby’s Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 468-470, 1038-1039.

McPheresen RA, Pincus MR. Henry’s Clinical Diagnosis and Management by Laboratory Methods, 22nd ed. Elsever Saunders: Philadelphia, 2011.

Jacobs DS, DeMott WR, Oxley DK. Jacobs & DeMott Laboratory Test Handbook, 5th ed. LexiComp: Cleveland2001.

Saenger AK. Red cell folate testing: Unwarranted and overutilized in the era of folic acid supplementation. November 2010 . Mayo Medical Laboratories. Available online at http://www.mayomedicallaboratories.com/articles/hottopics/transcripts/2010/2010-11a-rbc/2010-11a-rbc.html. Accessed August 2011.

Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. St. Louis: Elsevier Saunders; 2006, Pp1100-1103.

Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL eds, (2005). Harrison’s Principles of Internal Medicine, 16th Edition, McGraw Hill, Pp 601-604.

Parietal Cell Antibodies, IgG, Serum. Mayo Medical Laboratories. Available online at http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/83728. Accessed February 2014.

Horowitz, D. (Updated 2014 February 25). Intrinsic Factor. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/002381.htm. Accessed February 2014.

Chen, Y. (Updated 2014 February 24). Anemia – B12 deficiency. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000574.htm. Accessed February 2014.

(2014 August). Vitamin B12 Deficiency Evaluation. Mayo Medical Laboratories. Available online at http://www.mayomedicallaboratories.com/it-mmfiles/Vitamin_B12_Deficiency_Evaluation.pdf through http://www.mayomedicallaboratories.com. Accessed February 2014.

Test 83632 : Pernicious Anemia Cascade. Mayo Medical Laboratories. Available online at www.mayomedicallaboratories.com/interpretive-guide/?alpha=P&unit_code=83632. Accessed February 2014.

Singh, N. (Updated 2014 September 23). Vitamin B-12 Associated Neurological Diseases Treatment & Management. Medscape Reference. Available online at http://emedicine.medscape.com/article/1152670-treatment. Accessed February 2014.

Maakaron, J.E. (Updated 2014 March 20). Macrocytosis Treatment and Management. Medscape Reference. Available online at http://emedicine.medscape.com/article/203858-treatment. Accessed February 2014.

Coffey-Vega , K. (Updated 2013 March 22). Folic Acid Deficiency. Medscape. Available online at http://emedicine.medscape.com/article/200184-overview. Accessed February 2014.

Gersten, T. (Updated 2013 September 20). Folate Deficiency. Medline Plus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000354.htm. Accessed February 2014.

Johnson, L. (Updated 2014 October). Folate. Merck Manual. Available online at http://www.merckmanuals.com/professional/nutritional_disorders/vitamin_deficiency_dependency_and_toxicity/folate.html. Accessed February 2014.

Gersten, T. (Updated 2014 February 24). Vitamin B12 Level. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003705.htm. Accessed February 2014.

Gersten, T. (Reviewed 2013 September 20). Folate Deficiency. Pubmed Health. Available online at http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001394/. Accessed February 2014.

(©2015) Linus Pauling Institute. Vitamin B12. Available online at http://lpi.oregonstate.edu/infocenter/vitamins/vitaminB12/. Accessed March 2015.

(©2015) Linus Pauling Institute. Folate. Available online at http://lpi.oregonstate.edu/infocenter/vitamins/fa/. Accessed March 2015.

Scarpa E, et.al. Undetected vitamin B12 deficiency due to false normal assay results. Blood Transfus. 2013 Oct; 11(4): 627–629. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3827408/. Accessed April 2015.

 

Ask a Laboratory Scientist

This form enables patients to ask specific questions about lab tests. Your questions will be answered by a laboratory scientist as part of a voluntary service provided by one of our partners, American Society for Clinical Laboratory Science. Please allow 2-3 business days for an email response from one of the volunteers on the Consumer Information Response Team.

Ask a Laboratory Scientist